Substaging pathologically organ confined (pT2) prostate cancer: an exercise in futility?

Specific spatial distribution patterns of tumor foci are associated with a low risk of biochemical recurrence in pT2pN0R0 prostate cancer

BACKGROUND

The previous attempts for pT2 substaging of prostate cancer (PCa) were insufficient in providing prognostic subgroups and the search for new prognostic parameters to subcategorize pT2 PCa is, therefore, needed. Therefore, the current study investigated the association between tumor distribution patterns and the biochemical recurrence (BCR)-free survival rate in pT2pN0R0 PCa.

METHODS

Following radical prostatectomy, the anatomical distribution of PCa in 743 men with pT1-pT3pN0 disease was analyzed to determine 20 types of PCa distribution patterns. Then, 245 men with pT2pN0R0 PCa was considered for prognostic evaluation with a mean follow-up period of 60 months. The spatial distribution patterns of PCa were evaluated using a cMDX^©-based map model of the prostate. An analysis including 552,049 comparison operations was performed to assist in the evaluation of the similarity levels of the distribution patterns. A k-mean cluster analysis was applied to determine groups with similar distribution patterns. A decision-tree analysis was performed to divide these groups according to frequency of BCR. The BCR-free survival rate was analyzed using Kaplan-Meier curves. Predictors of progression were investigated using a Cox proportional hazards model.

RESULTS

BCR occurred in 8.2% of the 245 men with pT2pN0R0 PCa. The median time of recurrence was 60 months (interquartile range [IQR]: 42-77). In univariate and multivariate analyses, the prostate volume and the distribution patterns were independent predictors for BCR, whereas the sub-staging of pT2 tumors, Gleason grading, prostate-specific antigen (PSA) level, and relative tumor volume were not. In the patients with pT2pN0R0 disease, PCa distribution patterns with the apical involvement were significantly associated with the risk of BCR (P = 0.001).

CONCLUSION

The spread tumor patterns with the apical involvement are associated with a high-risk of BCR in the pT2 tumor stage. The vertical tumor spread could be considered in developing improved prognostic pT2 sub-categories.

In Organ-confined Prostate Cancer, Tumor Quantitation Not Found to Aid in Prediction of Biochemical Recurrence

In the eighth edition AJCC staging, all organ-confined disease is assigned pathologic stage T2, without subclassification. We investigated whether total tumor volume (TTV) and/or maximum tumor diameter (MTD) of the index lesion are useful in improving prediction of biochemical recurrence (BCR) in pT2 patients. We identified 1657 patients with digital tumor maps and quantification of TTV/MTD who had pT2 disease on radical prostatectomy (RP). Multivariable Cox regression models were used to assess whether TTV and/or MTD are independent predictors of BCR when adjusting for a base model incorporating age, preoperative prostate-specific antigen, RP grade group, and surgical margin status. If either tumor quantification added significantly, we calculated and reported the c-index. Ninety-five patients experienced BCR after RP; median follow-up for patients without BCR was 5.7 years. The c-index was 0.737 for the base model. Although there was some evidence of an association between TTV and BCR (P=0.088), this did not meet conventional levels of statistical significance and only provided a limited increase in discrimination (0.743; c-index improvement: 0.006). MTD was not associated with BCR (P>0.9). In analyses excluding patients with grade group 1 on biopsy who would be less likely to undergo RP in contemporary practice (622 patients; 59 with BCR), TTV/MTD was not a statistically significant predictor (P=0.4 and 0.8, respectively). Without evidence that tumor quantitation, in the form of either TTV or MTD of the index lesion, is useful for the prediction of BCR in pT2 prostate cancer, we cannot recommend its routine reporting.

The TNM 8th edition: Validation of the proposal for organ - confined (pT2) prostate cancer

Purpose:

The 8^th edition of the TNM has been updated and improved in order to ensure a high degree of clinical relevance. A major change in prostate includes pathologically organ - confined disease to be considered pT2 and no longer subclassified by extent of involvement or laterality. The aim of this study was to validate this major change.

Materials and Methods:

Prostates were step - sectioned from 196 patients submitted to radical prostatectomy with organ confined disease (pT2) and negative surgical margins. Tumor extent was evaluated by a semiquantitative point count method. The dominant nodule extent was recorded as the maximal number of positive points of the largest single focus of cancer from the quadrants. Laterality was considered as either total tumor extent (Group 1) or index tumor extent (Group 2). Time to biochemical recurrence was analyzed with the Kaplan - Meier product limit analysis and prediction of shorter time to biochemical recurrence with Cox proportional hazards model.

Results:

In Group 1, 43 / 196 (21.9%) tumors were unilateral and 153 / 196 (78.1%) bilateral and in Group 2, 156 / 196 (79.6%) tumors were unilateral and 40 / 196 (20.4%) bilateral. In both groups, comparing unilateral vs bilateral tumors, there was no significant clinicopathological difference, and no significant association with time as well as prediction of shorter time to biochemical recurrence following surgery.

Conclusions:

Pathologic sub - staging of organ confined disease does not convey prognostic information either considering laterality as total tumor extent or index tumor extent. Furthermore, no correlation exists between digital rectal examination and pathologic stage.

Evolution in Prostate Cancer Staging: Pathology Updates From AJCC 8th Edition and Opportunities That Remain

The Tumor-Nodes-Metastasis system at the core of prognostic staging has been recently updated in the American Joint Committee on Cancer (AJCC) 8th edition, published in 2016. For prostate cancer, significant changes in staging of organ-confined disease, inclusion of a new grade grouping, and provision of levels of evidence for these modifications are part of what differentiates the 8th edition AJCC from prior iterations. Herein, the rationale underlying these changes is detailed. In addition, data elements not well represented in the present system are highlighted as opportunities for fresh study that may impact future AJCC classifications.

Prostate cancer - major changes in the American Joint Committee on Cancer eighth edition cancer staging manual

Answer questions and earn CME/CNE The eighth edition of the American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) Staging Manual has been updated and improved to ensure the highest degree of clinical relevance and to improve its utility for patient evaluation and clinical research. Major changes include: 1) pathologically organ-confined disease is now considered pT2 and is no longer subclassified by extent of involvement or laterality, 2) tumor grading now includes both the Gleason score (as in the seventh edition criteria) and the grade group (introduced in the eighth edition criteria), 3) prognostic stage group III includes select, organ-confined disease based on prostate-specific antigen and Gleason/grade group status, and 4) 2 statistical prediction models are included in the staging manual. The AJCC will continue to critically analyze emerging prostate cancer biomarkers and tools for their ability to prognosticate and guide treatment decision making with the highest level of accuracy and confidence for patients and physicians. CA Cancer J Clin 2017;67:245-253. © 2017 American Cancer Society.

Should pathologists continue to use the current pT2 substaging system for reporting of radical prostatectomy specimens?

OBJECTIVES

Pathologic staging tries to maintain symmetry with clinical staging, allowing a direct comparison of both. However, in contrast to clinical substaging of T2 prostate cancers, is controversial whether pathologic T2 substaging conveys prognostic information. The aim of our study is to analyze the clinicopathologic findings and the prognostic information comparing the clinical with the pathological T2 substaging of patients submitted to radical prostatectomy.

MATERIALS AND METHODS

Using the 2009 TNM staging system, 169 patients with clinical stage T2a were compared with patients with stage T2b/T2c, and 142 patients with pathological stage T2a were compared with patients with stage T2c. All surgical specimens were step-sectioned. Using a semiquantitative point-count method for tumor extent evaluation, all insignificant tumors were excluded from analysis. Clinicopathological characteristics were compared between the groups. Biochemical recurrence data were compared using log-rank analysis, and significant predictors of time to biochemical recurrence were determined using univariate and multivariate Cox proportional hazards model.

RESULTS

There was significant difference in biochemical recurrence rates between men with clinical T2a versus T2b/T2c tumors but no difference between men with pathological T2a versus T2c tumors. No patient in pathologic stage T2b was found. On multivariate analysis, clinical stage T2b/T2c was independent predictor of time to biochemical recurrence following surgery but not pathological stage T2c.

CONCLUSIONS

There is lack of symmetry between clinical and pathological T2 substaging as predictors of time to biochemical recurrence following surgery. The findings support a reevaluation of the TNM pathologic T2 stage, which should not be substratified.

International Society of Urological Pathology (ISUP) Consensus Conference on Handling and Staging of Radical Prostatectomy Specimens. Working group 2: T2 substaging and prostate cancer volume

The 2009 International Society of Urological Pathology consensus conference in Boston made recommendations regarding the standardization of pathology reporting of radical prostatectomy specimens. Issues relating to the substaging of pT2 prostate cancers according to the TNM 2002/2010 system, reporting of tumor size/volume and zonal location of prostate cancers were coordinated by working group 2. A survey circulated before the consensus conference demonstrated that 74% of the 157 participants considered pT2 substaging of prostate cancer to be of clinical and/or academic relevance. The survey also revealed a considerable variation in the frequency of reporting of pT2b substage prostate cancer, which was likely a consequence of the variable methodologies used to distinguish pT2a from pT2b tumors. Overview of the literature indicates that current pT2 substaging criteria lack clinical relevance and the majority (65.5%) of conference attendees wished to discontinue pT2 substaging. Therefore, the consensus was that reporting of pT2 substages should, at present, be optional. Several studies have shown that prostate cancer volume is significantly correlated with other clinicopathological features, including Gleason score and extraprostatic extension of tumor; however, most studies fail to demonstrate this to have prognostic significance on multivariate analysis. Consensus was reached with regard to the reporting of some quantitative measure of the volume of tumor in a prostatectomy specimen, without prescribing a specific methodology. Incorporation of the zonal and/or anterior location of the dominant/index tumor in the pathology report was accepted by most participants, but a formal definition of the identifying features of the dominant/index tumor remained undecided.