Does Subclassification of Pathologically Organ Confined (pT2) Prostate Cancer Provide Prognostic Discrimination of Outcomes after Radical Prostatectomy?

Validation of the updated eighth edition of AJCC for prostate cancer: Removal of pT2 substages - Does extent of tumor involvement matter?

BACKGROUND

Updates in the eighth edition of the AJCC prostate cancer staging manual include removal of the organ-confined (pT2) substages.

METHODS

Retrospective analyses of 12,028 pT2 patients that underwent radical prostatectomy between 2003 and 2016 and did not receive neo- or adjuvant treatments. Kaplan-Meier curves as well as multivariable Cox-regression analyses compared biochemical recurrence (BCR), metastatic progression (MP) and overall mortality (OM) between the 3 subcategories (pT2a, pT2b and pT2c).

RESULTS

After surgery, 1,441 patients were classified as pT2a, 126 as pT2b and 10.495 as pT2c. Five-year BFS rates for pT2a, pT2b and pT2c were 92.0% vs. 97.4% vs. 88.0%. For the same groups, 5-year MP-FS rates were 99.5% vs. 100% vs. 99.0% and 5-year OS rates were 98.0% vs. 98.2% vs. 97.7%. In multivariable analyses pT2 substratification did not reach independent predictor status for biochemical recurrence, MP or overall mortality.

CONCLUSIONS

Substratification of pT2 prostate cancer was not predictive for further disease progression. Therefore, removing the substages simplifies the staging system without loss of important information.

Subclassification of pathologically organ-confined (pT2) prostate cancer does not significantly predict postoperative outcomes in Korean males

Purpose

We evaluated the prognostic association of pT2 subclassification with the oncological outcomes in patients with prostate cancer (PCa) who underwent radical prostatectomy (RP) in South Korea.

Materials and Methods

We retrospectively reviewed 3,529 patients who underwent RP for pathologically organ-confined PCa between 2003 and 2017 at Seoul National University Bundang Hospital. We analyzed the differences in the rates of biochemical recurrence (BCR), overall survival (OS), and cancer-specific survival (CSS) between pT2 substages.

Results

According to the 2002 TNM staging system, 362 (15.3%) and 2,000 patients (84.5%) had T2a (involving one-half or less of a unilateral lobe) and T2c (involving bilateral lobes) diseases. Four patients (0.2%) had T2b (involving more than one-half of a unilateral lobe) disease and none of them developed BCR. The mean follow-up period was 8.4±3.7 years and 175 patients (7.4%) had BCR. On multivariable analysis, pT2 subclassification (pT2a/b vs. pT2c) was not a significant predictor of BCR (p=0.224) or OS (p=0.311). Biochemical disease-free survival (p=0.091), OS (p=0.502), and CSS (p=0.063) showed no significant difference between pT2 substages.

Conclusions

Our study revealed that the pT2 subclassification of PCa in Korean males provided no value for predicting BCR, OS, and CSS after RP, which agrees with recently reported results based on the updated 8th version of the American Joint Committee on Cancer (AJCC) TNM staging system.