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Article of the month: Risk of metastatic disease on 68-gallium‐prostate‐specific membrane antigen PET/CT scan for primary staging of 1253 men at the diagnosis of PCa

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Every month, the Editor-in-Chief selects an Article of the Month from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an editorial  and a video prepared by the authors. These are intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation. 

If you only have time to read one article this month, it should be this one.

Risk of metastatic disease on 68Gallium‐prostate‐specific membrane antigen positron emission tomography/computed tomography scan for primary staging of 1253 men at the diagnosis of prostate cancer

John W. Yaxley*†‡, Sheliyan Raveenthiran†‡, François-Xavier Nouhaud‡§, Hemamali Samaratunga†¶, William J. Yaxley†‡, Geoff Coughlin*‡, Anna J. Yaxley**, Troy Gianduzzo††, Boon Kua‡‡, Louise McEwan‡‡ and David Wong‡‡

 

*Wesley Urology Clinic, †Department of Medicine, University of Queensland, ‡Royal Brisbane and Women’s Hospital, Brisbane, Queensland, Australia, §Department of Urology, Rouen University Hospital, Rouen, France, Aquesta Uro-pathology, **School of Medicine, Griffith University, ††Brisbane Prostate Clinic, and ‡‡Wesley Medical Imaging, Brisbane, Queensland, Australia

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Abstract

Objective

To determine the number of men with 68gallium‐prostate‐specific membrane antigen positron emission tomography/computed tomography (68Ga‐PSMA PET/CT) avid metastasis at diagnosis, as most data on 68Ga‐PSMA PET/CT are for the evaluation of recurrent disease after primary treatment and to our knowledge this study is the largest series of primary prostate cancer staging with 68Ga‐PSMA PET/CT.

Patients and Methods

A retrospective review conducted on 1253 consecutive men referred by urologists or radiation oncologists to our tertiary referral centre for 68Ga‐PSMA PET/CT scan for staging at the initial diagnosis of prostate cancer between July 2014 and June 2018.

The primary outcome measure was to determine the risk of metastasis based on 68Ga‐PSMA PET/CT. Patients were risk stratified based on histological biopsy International Society of Urological Pathology (ISUP) grade, prostate‐specific antigen (PSA) level, and staging with pre‐biopsy multiparametric magnetic resonance imaging (mpMRI). Univariate and multivariate logistic regression were used to analyse results.

Results

The median PSA level was 6.5 ng/mL and median ISUP grade was 3, with high‐risk disease in 49.7%. The prostate primary was PSMA avid in 91.7% of men. Metastatic disease was identified in 12.1% of men, including 8.2% with a PSA level of <10 ng/mL and 43% with a PSA level of >20 ng/mL. Metastases were identified in 6.4% with ISUP grade 2–3 and 21% with ISUP grade 4–5. Pre‐biopsy mpMRI identified metastasis in 8.1% of T2 disease, increasing to 42.4% of T3b. Lymph node metastases were suspected in 107 men, with 47.7% outside the boundaries of an extended pelvic lymph node dissection. Skeletal metastases were identified in 4.7%. In men with intermediate‐risk prostate cancer, metastases were identified in 5.2%, compared to 19.9% with high‐risk disease.

Conclusions

These results support the use of 68Ga‐PSMA PET/CT for primary staging of prostate cancer. Increasing PSA level, ISUP grade and radiological staging with mpMRI were all statistically significant prognostic factors for metastasis on both univariate and multivariate analysis.

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Editorial: PSMA PET/CT imaging for primary staging of intermediate and high-risk PCa

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In this month’s issue Yaxley et al. [1] describe a retrospective study of 68Ga-labelled prostate specific membrane antigen (68Ga-PSMA) positron emission tomography – computed tomography (PET/CT) in 1253 men at primary staging. The primary aim was to determine the risk of metastatic disease on 68Ga-PSMA PET/CT in risk categories including prostate specific antigen (PSA) level, ISUP grade and multiparametric magnetic resonance imaging (mpMRI) stage. The majority of patients had PSA < 10 ng/ml (78%) and / or T2 tumours (74%) with a relatively even distribution across ISUP grades from 1 to 5. Overall, metastases were detected in 12.1% of men and unsurprisingly, were more common in patients with high PSA >20ng/ml and/or ISUP 4-5 and/or T3b stage. Increasing PSA, ISUP grade and T-stage were all statistically significant prognostic factors on univariate and multivariate analysis. In men with at least one intermediate risk factor (T2, PSA 10-20 ng/ml, ISUP 2-3), 5.2% had metastases and in those with at least one high risk factor, 19.9% had PSMA-avid metastases.

On a sub-analysis of lymph node metastases (107 men), there was increased risk of nodal disease with increasing PSA, ISUP grade and T-stage. Of note, nearly 50% of lymph node metastases were outside an extended lymph node dissection field. Skeletal metastases, occurring in 59 men, were also more frequent in these higher risk groups. Interestingly, not all primary tumours (91.7%) were PSMA-avid (SUVmax > 3.0), consistent with previous estimations of less than 10% of prostate cancer not expressing PSMA significantly.

There is a large body of evidence supporting the use of 68Ga-PSMA PET/CT in biochemical recurrence of prostate cancer, with superior sensitivity over other PET tracers such as 18F-choline or 18F-fluciclovine, particularly at low PSA levels (1 and 2ng/ml, respectively) [2,3]. There is less evidence supporting the use of 68Ga-PSMA PET/CT in primary staging, although the literature that does exist is positive. In 130 patients with intermediate or high-risk disease, sensitivity and specificity for lymph node detection on a template-based analysis has been reported to be 68.3% and 99.1%, respectively, significantly better sensitivity than conventional morphological imaging (27.3% and 97.1%, respectively) [4]. Whilst, the negative predictive value might not be sufficiently high to avoid considering lymph node dissection in patients at increased risk of nodal metastases, there is nevertheless potential to substantially improve on conventional morphological imaging for nodal staging. In addition, there is evidence that 68Ga-PSMA PET/CT leads to changes in management in at least 21% of patients being staged with intermediate or high-risk disease [5]. The large retrospective cohort reported by Yaxley et al. [1] contributes to this growing evidence base and suggests that 68Ga-PSMA PET/CT has a place in staging high-risk, and probably intermediate risk, patients before definitive treatment. The retrospective nature allows potential referral bias but the data benefits from a large cohort in real-life current practice.

What this study does not tell us is the incremental benefit of 68Ga-PSMA PET/CT over conventional imaging with mpMRI, bone scan and CT scan. However, the prospectively recruiting proPSMA study will provide these data shortly [6]. Secondly, no histopathological or follow up reference standard was available in this study. However, 68Ga-PSMA PET/CT is known to be very specific with few false positive results and the authors adopted a relatively robust criterion for positivity (moderate or high uptake with a CT correlate) to minimise false positive results. However, some sensitivity may have been lost, e.g. mildly positive metastases or PSMA-positive but CT-negative bone lesions, a not infrequent occurrence in our experience. An additional practical detail is that contrast-enhanced CT was employed to aid differentiation of ureteric activity from abdominal and pelvic lymph nodes. This is not routine in all PET departments.

The results from the proPSMA study are eagerly awaited [6]. In the meantime, the imaging and clinical prostate community will also need to tackle the issues of having several 68Ga and 18F-labelled PSMA analogues available to choose from, with subtle differences in biodistribution, diagnostic accuracy and cost. There seems no doubt however, that PSMA-based PET imaging will continue to play a substantial part in the management of patients with prostate cancer at various points in their management pathway and that robust prospective evidence will continue to accumulate to a level that funders will not be able to ignore.

References

  1. Yaxley J, Raveenthiran S, Nouhaud FX, et al. Risk of metastatic disease on 68Ga-PSMA PET/CT scan for primary staging of 1253 men at the diagnosis of prostate cancer. BJU Int 2019; xx: xxx-xxx.
  2. Treglia G, Pereira Mestre R, Ferrari M, et al. Radiolabelled choline versus PSMA PET/CT in prostate cancer restaging: a meta-analysis. Am J Nucl Med Mol Imaging 2019; 9: 127-39.
  3. Calais J, Ceci F, Nguyen K, et al. Prospective head-to-head comparison of 18F-fluciclovine and 68Ga-PSMA-11 PET/CT for localization of prostate cancer biochemical recurrence after primary prostatectomy. J Clin Oncol 2019; 37: 7_suppl, 15-15.
  4. Maurer T, Gschwend JE, Rauscher I, et al. Diagnostic efficacy of (68)Gallium-PSMA positron emission tomography compared to conventional imaging for lymph node staging of 130 consecutive patients with intermediate to high risk prostate cancer. J Urol 2016; 195: 1436-43.
  5. Roach PJ, Francis R, Emmett L, et al. The Impact of (68)Ga-PSMA PET/CT on Management Intent in Prostate Cancer: Results of an Australian Prospective Multicenter Study. J Nucl Med 2018; 59: 82-8.
  6. Hofman MS, Murphy DG, Williams SG, et al. A prospective randomized multicentre study of the impact of gallium-68 prostate-specific membrane antigen (PSMA) PET/CT imaging for staging high-risk prostate cancer prior to curative-intent surgery or radiotherapy (proPSMA study): clinical trial protocol. BJU Int 2018; 122: 783-3.

 

Video: Risk of metastatic disease on 68-Ga‐PSMA PET/CT scan for primary staging of 1253 men with PCa

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Risk of metastatic disease on 68Gallium‐prostate‐specific membrane antigen positron emission tomography/computed tomography scan for primary staging of 1253 men at the diagnosis of prostate cancer

Read the full article

Abstract

Objective

To determine the number of men with 68gallium‐prostate‐specific membrane antigen positron emission tomography/computed tomography (68Ga‐PSMA PET/CT) avid metastasis at diagnosis, as most data on 68Ga‐PSMA PET/CT are for the evaluation of recurrent disease after primary treatment and to our knowledge this study is the largest series of primary prostate cancer staging with 68Ga‐PSMA PET/CT.

Patients and Methods

A retrospective review conducted on 1253 consecutive men referred by urologists or radiation oncologists to our tertiary referral centre for 68Ga‐PSMA PET/CT scan for staging at the initial diagnosis of prostate cancer between July 2014 and June 2018.

The primary outcome measure was to determine the risk of metastasis based on 68Ga‐PSMA PET/CT. Patients were risk stratified based on histological biopsy International Society of Urological Pathology (ISUP) grade, prostate‐specific antigen (PSA) level, and staging with pre‐biopsy multiparametric magnetic resonance imaging (mpMRI). Univariate and multivariate logistic regression were used to analyse results.

Results

The median PSA level was 6.5 ng/mL and median ISUP grade was 3, with high‐risk disease in 49.7%. The prostate primary was PSMA avid in 91.7% of men. Metastatic disease was identified in 12.1% of men, including 8.2% with a PSA level of <10 ng/mL and 43% with a PSA level of >20 ng/mL. Metastases were identified in 6.4% with ISUP grade 2–3 and 21% with ISUP grade 4–5. Pre‐biopsy mpMRI identified metastasis in 8.1% of T2 disease, increasing to 42.4% of T3b. Lymph node metastases were suspected in 107 men, with 47.7% outside the boundaries of an extended pelvic lymph node dissection. Skeletal metastases were identified in 4.7%. In men with intermediate‐risk prostate cancer, metastases were identified in 5.2%, compared to 19.9% with high‐risk disease.

Conclusions

These results support the use of 68Ga‐PSMA PET/CT for primary staging of prostate cancer. Increasing PSA level, ISUP grade and radiological staging with mpMRI were all statistically significant prognostic factors for metastasis on both univariate and multivariate analysis.

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Article of the week: Biparametric vs multiparametric prostate MRI for the detection of PCa in treatment‐naïve patients

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Every week, the Editor-in-Chief selects an Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an editorial written by a prominent member of the urological community, and a video produced by the authors. These are intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation. 

If you only have time to read one article this week, it should be this one.

Biparametric vs multiparametric prostate magnetic resonance imaging for the detection of prostate cancer in treatment-naïve patients: a diagnostic test accuracy systematic review and meta-analysis

Mostafa Alabousi*, Jean-Paul Salameh†‡, Kaela Gusenbauer§, Lucy Samoilov, Ali Jafri**, Hang Yu§ and Abdullah Alabousi††

 

*Department of Radiology, McMaster University, Hamilton, †Department of Clinical Epidemiology and Public Health, University of Ottawa, ‡The Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, §Department of Medicine, McMaster University, Hamilton, Department of Medicine, Western University, London, ON, Canada, **Department of Medicine, New York Institute of Technology School of Osteopathic Medicine, Glen Head, NY, USA, and ††Department of Radiology, St Joseph’s Healthcare, McMaster University, Hamilton, ON, Canada

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Abstract

Objective

To perform a diagnostic test accuracy (DTA) systematic review and meta‐analysis comparing multiparametric (diffusion‐weighted imaging [DWI], T2‐weighted imaging [T2WI], and dynamic contrast‐enhanced [DCE] imaging) magnetic resonance imaging (mpMRI) and biparametric (DWI and T2WI) MRI (bpMRI) in detecting prostate cancer in treatment‐naïve patients.

Methods

The Medical Literature Analysis and Retrieval System Online (MEDLINE) and Excerpta Medica dataBASE (EMBASE) were searched to identify relevant studies published after 1 January 2012. Articles underwent title, abstract, and full‐text screening. Inclusion criteria consisted of patients with suspected prostate cancer, bpMRI and/or mpMRI as the index test(s), histopathology as the reference standard, and a DTA outcome measure. Methodological and DTA data were extracted. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)‐2 tool. DTA metrics were pooled using bivariate random‐effects meta‐analysis. Subgroup analysis was conducted to assess for heterogeneity.

Results

From an initial 3502 studies, 31 studies reporting on 9480 patients (4296 with prostate cancer) met the inclusion criteria for the meta‐analysis; 25 studies reported on mpMRI (7000 patients, 2954 with prostate cancer) and 12 studies reported on bpMRI DTA (2716 patients, 1477 with prostate cancer). Pooled summary statistics demonstrated no significant difference for sensitivity (mpMRI: 86%, 95% confidence interval [CI] 81–90; bpMRI: 90%, 95% CI 83–94) or specificity (mpMRI: 73%, 95% CI 64–81; bpMRI: 70%, 95% CI 42–83). The summary receiver operating characteristic curves were comparable for mpMRI (0.87) and bpMRI (0.90).

Conclusions

No significant difference in DTA was found between mpMRI and bpMRI in diagnosing prostate cancer in treatment‐naïve patients. Study heterogeneity warrants cautious interpretation of the results. With replication of our findings in dedicated validation studies, bpMRI may serve as a faster, cheaper, gadolinium‐free alternative to mpMRI.

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Editorial: Dropping the GAD – just a fad?

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It is not without irony that, at the very moment that the UK’s National Institute for Health and Care Excellence (NICE) is poised to ratify the recommendation that multiparametric MRI (mpMRI) be introduced into the prostate cancer diagnostic pathway, we are seeking to significantly modify the very intervention on which they are about to provide judgement on [1].

The modification proposed is both compelling and plausible, as it renders the process of imaging the prostate in order to detect and localise clinically significant prostate cancer; simpler, quicker, safer and cheaper. It entails dropping the most complex and time‐consuming component of the three multiparametric sequences, the dynamic (time‐dependent) T1‐weighted gadolinium‐enhanced (GAD) sequence. This was a sequence that was, in the early days of MRI, imbued to have biological significance because it was capable of exploiting the differences in the microvascular architecture and function that we have tended to associate with cancer and non‐cancer in order to discriminate between the two. Or so we thought [2].

The systematic review in this issue of the BJUI by Alabousi et al. [3] explores, via the process of systematic review, whether the omission of the T1‐GAD sequence results in any clinically important reduction in test performance when compared with the full sequence scan comprising traditionally of T2, diffusion and T1‐GAD sequences. It did not.

By any stretch this is a tough analysis to pull‐off, as T1‐GAD sequences are not standardised in terms of acquisition or reporting. Every group seems to manage the dynamic images in a different way. As such they tend to suffer from quality control issues, possibly to a greater extent than the T2 and diffusion sequences. The verification of the signal by biopsy strategy and sampling intensity will have varied across studies, as will the threshold of the definition of clinically significant prostate cancer. These inherent methodological problems are all familiar to readers and issues that are pertinent to any imaging study in the detection of prostate cancer. However, there are two issues that make any current assessment of GAD vs no GAD really problematic. The first is the almost exclusive reliance on single‐centre retrospective data. In the few studies that claim a prospective design no comparative data were available. Studies of this type are typical in the early phase of exploring a clinical question and will, in time, be corrected. The other, largely hidden, hardly discussed and truly problematic issue relates to the manner by which we synthesise an overall risk score from the MRI sequences that we derive. The near ubiquitous use of the Prostate Imaging‐Reporting and Data System (PI‐RADS) scoring system introduces a systematic bias by the manner in which a Boolean form of logic is used to decide on the degree of influence that each sequence has in relation to the overall score. According to the manner by which PI‐RADS is applied, it tends to render the T1‐GAD sequence subordinate (only relevant in a minority of cases), contingent (to T2/diffusion) and disparate (dependent on prostate zone) in the way it is invoked [4]. The result is, that within the PIRADS framework, the T1‐GAD sequence is destined to play a relatively small role in driving the overall summary score of risk. It might, therefore, not be too surprising if its removal made little difference to the overall detection of clinically significant prostate cancer.

So what are the next steps? Clearly this is a very important issue and a simpler, quicker, safer and cheaper MRI would be desirable from multiple perspectives. It would render what is currently a complex intervention that comprises an invasive component into a totally passive image acquisition in which no medically trained health professional need be present. It is almost certainly a pre‐requisite for adoption in resource-poor jurisdictions and for entertaining the role of MRI as a primary population‐based screening test.

It took a large number of randomised trials to get mpMRI accepted into the prostate cancer diagnostic pathway. What is the minimum amount of evidence required to disinvest in one of its key components? In other words how many clinically significant cancers would we tolerate missing in order to offer the less complex test?

A direct (head‐to‐head) non‐inferiority randomised comparative study would, following some of our own recent calculations, require >3000 men to participate, which might just prove a little too challenging. An alternative approach is a study in which men would have lesions declared using a Likert score, thereby making no prior assumptions on the role and utility of any single sequence, by traditional mpMRI (standard) but also by a T2‐diffusion MRI (experimental) with appropriate blinding. Some lesions would be private to either standard or experimental imaging but most, it is likely, would be shared. All would require sampling. The yield, the misses, the test accuracy for each approach, could be calculated with necessary adjustments for the inevitable incorporation and verification biases.

It is interesting to observe that in many parts of the world mpMRI was introduced by clinicians before a large body of evidence was accumulated because they felt it was the right thing to do [5]. It may well be the case that ‘dropping the GAD’ will be subject to the same decision‐making process and precede any definitive judgement based on reliable evidence. Recent activity on PubMed would suggest that this might already have happened [6].

References

  1. National Institute for Health and Care Excellence (NICE). Non‐invasive MRI scan for Prostate Cancer recommended by NICE. Available at: https://www.nice.org.uk/news/article/non-invasive-mri-scan-for-prostate-cancer-recommended-by-nice. Accessed May 2019.
  2. Little, RA, Barjat, H, Hare, JI et al. Evaluation of dynamic contrast‐enhanced MRI biomarkers for stratified cancer medicine: how do permeability and perfusion vary between human tumours? Magn Reson Imaging 2018; 46: 98– 105
  3. Alabousi, M, Salameh, JP, Gusenbauer, K et al. Biparametric vs multiparametric prostate magnetic resonance imaging for the detection of prostate cancer in treatment‐naïve patients: a diagnostic test accuracy systematic review and meta‐analysis. BJU Int 2019; 124: 209– 20
  4. Turkbey, B, Rosenkrantz, AB, Haider, MA et al. Prostate Imaging reporting and Data System version 2.1: 2019 update of Prostate Imaging Reporting and Data System version 2. Eur Urol 2019 [Epub ahead of print]. https://doi.org/10.1016/j.eururo.2019.02.033
  5. Ahmed, HU, Kirkham, A, Arya, M et al. Is it time to consider a role for MRI before prostate biopsy? Nat Rev Clin Oncol 2009; 6: 197– 20
  6. Xu, M, Fang, M, Zou, J et al. Using biparametric MRI radiomics signature to differentiate between benign and malignant prostate lesions. Eur J Radiol 2019; 114: 38– 44

 

Video: Biparametric vs multiparametric prostate MRI for the detection of PCa in treatment‐naïve patients: a diagnostic test accuracy systematic review and meta‐analysis

/by

Read the full article

Abstract

Objective

To perform a diagnostic test accuracy (DTA) systematic review and meta‐analysis comparing multiparametric (diffusion‐weighted imaging [DWI], T2‐weighted imaging [T2WI], and dynamic contrast‐enhanced [DCE] imaging) magnetic resonance imaging (mpMRI) and biparametric (DWI and T2WI) MRI (bpMRI) in detecting prostate cancer in treatment‐naïve patients.

Methods

The Medical Literature Analysis and Retrieval System Online (MEDLINE) and Excerpta Medica dataBASE (EMBASE) were searched to identify relevant studies published after 1 January 2012. Articles underwent title, abstract, and full‐text screening. Inclusion criteria consisted of patients with suspected prostate cancer, bpMRI and/or mpMRI as the index test(s), histopathology as the reference standard, and a DTA outcome measure. Methodological and DTA data were extracted. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)‐2 tool. DTA metrics were pooled using bivariate random‐effects meta‐analysis. Subgroup analysis was conducted to assess for heterogeneity.

Results

From an initial 3502 studies, 31 studies reporting on 9480 patients (4296 with prostate cancer) met the inclusion criteria for the meta‐analysis; 25 studies reported on mpMRI (7000 patients, 2954 with prostate cancer) and 12 studies reported on bpMRI DTA (2716 patients, 1477 with prostate cancer). Pooled summary statistics demonstrated no significant difference for sensitivity (mpMRI: 86%, 95% confidence interval [CI] 81–90; bpMRI: 90%, 95% CI 83–94) or specificity (mpMRI: 73%, 95% CI 64–81; bpMRI: 70%, 95% CI 42–83). The summary receiver operating characteristic curves were comparable for mpMRI (0.87) and bpMRI (0.90).

Conclusions

No significant difference in DTA was found between mpMRI and bpMRI in diagnosing prostate cancer in treatment‐naïve patients. Study heterogeneity warrants cautious interpretation of the results. With replication of our findings in dedicated validation studies, bpMRI may serve as a faster, cheaper, gadolinium‐free alternative to mpMRI.

 

 

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Article of the week: A transcriptomic signature of tertiary Gleason 5 predicts worse clinicopathological outcome

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Every week, the Editor-in-Chief selects an Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an editorial written by a prominent member of the urological community, and a video produced by the authors. These are intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation. 

If you only have time to read one article this week, it should be this one.

A transcriptomic signature of tertiary Gleason 5 predicts worse clinicopathological outcome

Alberto Martini*, Joanna Wang*, Nicholas M. Brown*, Shivaram Cumarasamy*, John P. Sfakianos*, Ardeshir R. Rastinehad*, Kenneth G. Haines III†, Nils Peter Wiklund*, Sujit S. Nair* and Ashutosh K. Tewari*

 

Departments of *Urology and †Pathology, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA

 

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Abstract

Objective

To investigate the genomic features of tertiary pattern 5 (TP5) on radical prostatectomy specimens in an effort to explain the poor clinical outcomes associated with this disease subtype.

Patients and methods

Data from 159 men with Gleason Grade Group (GGG) 3 or 4 were considered. All patients had Decipher diagnostic testing with transcript profiles and single‐channel array normalisation (SCAN)‐normalised expression of coding genes.

The relationship between Decipher and TP5 was investigated by linear and binary logistic regressions. A differential transcriptomic analysis between patients with and without TP5 was performed. The prognostic role of these genes on progression‐free survival (PFS) and overall survival (OS) was evaluated using The Cancer Genome Atlas.

Results

In all, 52/159 (33%) patients had GGG 3–4 with TP5 disease. TP5 was associated with a higher Decipher score (β 0.07, 95% confidence interval [CI] 0.02–0.13; P = 0.04) and higher likelihood of falling within the intermediate‐ or high‐risk categories (odds ratio 3.34, 95% CI 1.34–8.35; P = 0.01). Analysis of microarray data revealed an 18‐gene signature that was differentially expressed in patients with TP5; 13 genes were over‐ and five under‐expressed in the TP5 cohort.

The overexpression of cyclin dependent kinase inhibitor 2B (CDKN2B), polo‐like kinase 1 (PLK1), or cell division cycle 20 (CDC20) was associated with worse PFS. The group harbouring overexpression of at least one gene had a 5‐year PFS rate of 50% vs 74% in the group without overexpression (P < 0.001).

Conclusions

Our studies have elucidated unique genomic features of TP5, whilst confirming previous clinical findings that patients harbouring TP5 tend to have worse prognosis. This is the first RNA‐based study to investigate the molecular diversity of TP5 and the first correlating CDKN2B to poorer prognosis in patients with prostate cancer.

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Editorial: Transcriptomic signatures for tertiary pattern 5 in prostate cancer

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Significant evidence is now emerging and publications have shown that the molecular characterization of tumours represents an important approach to stratifying patients with prostate cancer into appropriate treatments and their responses, helping to inform the next steps in the care pathway of these patients [1]. Understanding the functional role of the genes included in these signatures also gives an insight into the biology of the disease and how it develops and progresses.

BJUI has published papers in the past describing gene signatures that are associated with pathological Gleason score as pathological markers of aggressiveness and their potential role in predicting outcome [2].

The paper by Martini et al. [3] in the current issue of BJUI adds to this important literature. In a cohort of 159 patients, of whom 52 had tertiary pattern 5 (TP5) prostate cancer, Martini et al. showed that TP5 was associated with higher risk categories in the Decipher genomic score. Their study supports the literature showing that patients with TP5 have an elevated likelihood of developing disease after radical prostatectomy and have a poor prognosis [4]. It should be noted, however, that this is a small cohort with few patients defined as having TP5 disease. As prostate cancer is highly heterogeneous and gene expression can also be affected by the patient’s background, additional validation of this finding will be required in independent cohorts.

Additional analysis of the 698 gene by Martini et al. [3] identified a unique RNA signature of 18 genes for the TP5 cohort. A limitation of using the 698 gene previously demonstrated to be related to prostate cancer is that those with TP5 disease may be a unique subset of patients that may be associated with unfamiliar pathological pathways and new genes. An examination of novel genes whose expression pattern is unique to patients with TP5 disease may reveal additional genes.

Martini et al. then used the independent TCGA provisional database to link the expression of these 18 genes with clinical features. Patients harbouring any of the three genes CDKN2B, PLK1 and CDC20 mRNA were found to have worse progression‐free survival. The authors go on to undertake analysis of the 18 genes using the ingenuity network analysis tool identifying pathways involved in the cell cycle, DNA replication and repair, cellular assembly, cell death and survival and gene expression, which would fit with the biology of progressive disease. They also revealed a role in the dedifferentiation process and progression of cells towards anaplasia. They specifically identified CDKN2B, which has previously been associated with tumour suppression but might actually be linked to tumour progression, and identified it for further investigation.

Finally the researchers found that 13 genes out of the 18‐gene TP5 signature are upregulated in tumour lesions with TP5. Following these results they performed a sensitivity analysis in which the expression values of the genes in the cohort with GGG3‐4 and TP5 were compared with those of patients with GGG5 and discovered that these genes were similarly overexpressed in both groups. This finding strengthens the hypothesis that these genes are implicated in the dedifferentiation process of tumour cells, but it also raises the question of whether the pattern of expression of these genes is unique to patients with TP5 only, or whether it is associated with every tumour (primary, secondary or tertiary) that is classified as GGG5. Further research is needed to understand what the clinical significance of this genetic signature is and what pathological process it describes in practice.

This investigation into the functional role of the genes has given an insight into the biology of prostate cancer progression and TP5 disease which might inform a future area of research for novel biomarker panels and therapeutic interventions.

by R. William Watson and Omri Taltsh

References

  1. Cucchiara, V, Cooperberg, MR, Dall’Era, M, Lin, DW, Montorsi, F, Schalken, JA, Evans, CP Genomic markers in prostate cancer decision making. Euro Urol 2018; 73: 572– 82
  2. Pellegrini, K, Sanda, MG, Patil, D, Long, Q, Santiago‐Jiménez, M, Takhar, M, Erho, N, Yousefi, K,Davicioni, E, Klein, EA, Jenkins, RB, Karnes, RJ, Moreno, CS Evaluation of a 24‐Gene signature for prognosis of metastatic events and prostate cancer‐specific mortality. BJU Int 2017; 119: 961– 7
  3. Martini, A, Wang, J, Brown, NM, Cumarasamy, S, Sfakianos, JP, Rastinehad, AR, Haines, KG,Wiklund, NP, Nair, SS, Tewari, AK A transcriptomic signature of tertiary Gleason 5 predicts worse clinicopathological outcome. BJU Int 2019; 124: 155– 62
  4. Whittemore, DE, Hick, EJ, Carter, MR, Moul, JW, Miranda‐Sousa, AJ, Sexton, WJ Significance of tertiary Gleason pattern 5 in Gleason score 7 radical prostatectomy specimens. J Urol 2008; 179:516– 22

 

 

Video: A transcriptomic signature of tertiary Gleason 5 predicts worse clinicopathological outcome

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A transcriptomic signature of tertiary Gleason 5 predicts worse clinicopathological outcome

by Alberto Martini

Read the full article

Abstract

Objective

To investigate the genomic features of tertiary pattern 5 (TP5) on radical prostatectomy specimens in an effort to explain the poor clinical outcomes associated with this disease subtype.

Patients and methods

Data from 159 men with Gleason Grade Group (GGG) 3 or 4 were considered. All patients had Decipher diagnostic testing with transcript profiles and single‐channel array normalisation (SCAN)‐normalised expression of coding genes.

The relationship between Decipher and TP5 was investigated by linear and binary logistic regressions. A differential transcriptomic analysis between patients with and without TP5 was performed. The prognostic role of these genes on progression‐free survival (PFS) and overall survival (OS) was evaluated using The Cancer Genome Atlas.

Results

In all, 52/159 (33%) patients had GGG 3–4 with TP5 disease. TP5 was associated with a higher Decipher score (β 0.07, 95% confidence interval [CI] 0.02–0.13; P = 0.04) and higher likelihood of falling within the intermediate‐ or high‐risk categories (odds ratio 3.34, 95% CI 1.34–8.35; P = 0.01). Analysis of microarray data revealed an 18‐gene signature that was differentially expressed in patients with TP5; 13 genes were over‐ and five under‐expressed in the TP5 cohort.

The overexpression of cyclin dependent kinase inhibitor 2B (CDKN2B), polo‐like kinase 1 (PLK1), or cell division cycle 20 (CDC20) was associated with worse PFS. The group harbouring overexpression of at least one gene had a 5‐year PFS rate of 50% vs 74% in the group without overexpression (P < 0.001).

Conclusions

Our studies have elucidated unique genomic features of TP5, whilst confirming previous clinical findings that patients harbouring TP5 tend to have worse prognosis. This is the first RNA‐based study to investigate the molecular diversity of TP5 and the first correlating CDKN2B to poorer prognosis in patients with prostate cancer.

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Article of the week: 68Ga‐PSMA PET/CT predicts complete biochemical response from RP and lymph node dissection in intermediate‐ and high‐risk PCa

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Every week, the Editor-in-Chief selects an Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an editorial written by a prominent member of the urological community. These are intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation. 

If you only have time to read one article this month, it should be this one.

Gallium‐68‐prostate‐specific membrane antigen (68Ga‐PSMA) positron emission tomography (PET)/computed tomography (CT) predicts complete biochemical response from radical prostatectomy and lymph node dissection in intermediate‐ and high‐risk prostate cancer

 

Pim J. van Leeuwen*, Maarten Donswijk†, Rohan Nandurkar‡, Phillip Stricker§¶, Bao Ho**, Stijn Heijmink††, Esther M.K. Wit*, Corinne Tillier*, Erik van Muilenkom*, Quoc Nguyen§, Henk G. van der Poel* and Louise Emmett‡§**

 

*Department of Urology, †Department of Nuclear Medicine, The Netherlands Cancer Institute, Amsterdam, The Netherlands, ‡Faculty of Medicine, University of New South Wales Sydney, §The Australian Prostate Cancer Research Centre-NSW, The Garvan Institute of Medical Research, St Vincent’s Clinic, **Department of Theranostics and Nuclear Medicine, St Vincent’s Hospital Sydney, Sydney, New South Wales, Australia and ††Department of Radiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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Abstract

Objective

To determine the value of gallium‐68‐prostate‐specific membrane antigen (68Ga‐PSMA)‐11 positron emission tomography (PET) /computed tomography (CT) in men with newly diagnosed prostate cancer.

Patients and methods

We analysed results of 140 men with intermediate‐ and high‐risk prostate cancer. All men underwent 68Ga‐PSMA‐11 PET/CT and multiparametric magnetic resonance imaging (mpMRI) before radical prostatectomy (RP) with extended pelvic lymph node (LN) dissection. For each patient, the clinical and pathological features were recorded. Prostate‐specific antigen (PSA) was documented at staging scan, and after RP, at a median (interquartile range) of 110 (49–132) days. A PSA level of ≥0.03 ng/mL was classified as biochemical persistence (BCP). Logistic regression was performed for association of clinical variables and BCP.

Results

In these 140 patients with intermediate‐ and high‐risk prostate cancer, 27.1% had PSMA PET/CT‐positive findings in the pelvic LNs. Sensitivity and specificity for detection of LN metastases were 53% and 88% (PSMA PET/CT) and 14% and 99% (mpMRI), respectively. The overall BCP rate was 25.7%. The BCP rate was 16.7% in men who were PSMA PET/CT LN‐negative compared to 50% in men who were PSMA PET/CT LN‐positive (P < 0.05). The presence of PSMA‐positive pelvic LNs was more predictive of BCP after RP than cT‐stage, PSA level, and the Gleason score, adjusted for surgical margins status.

Conclusions

68Ga‐PSMA‐11 PET/CT is highly predictive of BCP after RP, and should play an important role informing men with intermediate‐ or high‐risk prostate cancer.

 

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