Re-evaluating the biological significance of seminal vesicle invasion (SVI) in locally advanced prostate cancer - Abstract

OBJECTIVE: To examine the impact of seminal vesicle invasion (SVI) in patients with locally advanced (pT3) prostate cancer on clinical outcome.

To explore the clinical association of SVI with metastatic disease. To distinguish between the possibilities that either seminal vesicles possess their own biological significance and represent a privileged staging site for systemic tumour cell dissemination, or that their invasion is a surrogate marker for an aggressive large-volume poorly differentiated cancer.

PATIENTS AND METHODS: Patients with extraprostatic extension (EPE) and/or SVI were identified from a prospectively recorded and maintained prostate cancer database. Patients were categorised according to the presence of SVI as determined by routine pathological assessment. Tumour volumes were measured routinely by computed planimetry at the time of histological assessment. The impact of SVI on biochemical recurrence with a definition of a prostate-specific antigen (PSA) level of ≥0.2 ng/mL, as well as a clinically significant recurrence defined as failure with a PSA doubling time of < 6 months, was determined by univariable and multivariable Cox regression analysis.

RESULTS: Of 249 patients with pT3 disease, 46 (18%) had SVI, 40 (87%) by direct extension and six (13%) metastatic.  Tumours with SVI had significantly greater tumour burden as determined by total tumour volume (7.2 vs 3.7 mL, P < 0.001), index tumour volume (6.8 vs. 3.4 mL, P < 0.001) and percentage tumour volume (21.8 vs 12.4 %, P= 0.001).  After controlling for tumour volume and Gleason score, the presence of SVI did not significantly predict for the development of a significant PSA recurrence.

CONCLUSIONS: Our results suggest that SVI is a surrogate marker of larger and more aggressive tumours with higher Gleason scores rather than a privileged site of tumour cell dissemination.

Written by:
Sapre N, Pedersen J, Hong MK, Harewood L, Peters J, Costello AJ, Hovens CM, Corcoran NM.   Are you the author?
Department of Surgery, University of Melbourne, Royal Melbourne Hospital, Parkville; and the Australian Prostate Cancer Research CentreEpworth, Richmond TissuPath Specialist Pathology, Mount Waverley, Monash University Faculty of Medicine, VIC, Australia.

Reference: BJU Int. 2012 Dec;110 Suppl 4:58-63.
doi: 10.1111/j.1464-410X.2012.11477.x

PubMed Abstract
PMID: 23194127 Prostate Cancer Section