Prognostic significance and biopsy characteristics of prostate cancer with seminal vesicle invasion on radical prostatectomy: a nationwide population-based study

The objective of this study was to evaluate the prognostic significance of seminal vesicle invasion (SVI, pT3b) compared with extraprostatic extension (EPE) alone (pT3a) after radical prostatectomy, and to correlate pre-operative biopsy pathology with SVI and EPE. The National Prostate Cancer Register includes all prostate cancers diagnosed in Sweden. We analysed 4063 cases with stage category pT3a and 1371 cases with pT3b at radical prostatectomy between 2000 and 2012. Associations between pT3a and pT3b and progression were evaluated and adjusted for year, age, biopsy grade and s-PSA. Needle biopsy findings in these stages were compared. Patients with pT3b (n = 1371) had a higher risk of death from prostate cancer (HR 2.3, 95% CI 1.5-3.3, p < 0.001) and death from any cause (HR 1.5, 95% CI 1.2-1.8, p < 0.001) than those with pT3a (n = 4063). They were also more likely to be treated with post-operative radiotherapy (HR 1.5, 95% CI 1.4-1.7, p < 0.001) or androgen deprivation therapy (HR 3.0, 95% CI 2.5-3.7, p < 0.001), indicating clinical progression. Yet, disease-specific survival of patients with stage pT3b was 94% after 6 years. Median cancer extent in pre-operative biopsies of pT3a and pT3b was 14 and 24 mm (p < 0.001), number of positive cores was four and five, (p < 0.001) and biopsy Gleason score was 8-10 in 11.6% and 27.3%, respectively (p < 0.001). SVI of prostate cancer is associated with worse outcome after radical prostatectomy than EPE alone. However, few patients with SVI die within 6 years from surgery, suggesting that radical prostatectomy may be curative in locally advanced cancers.