[2006] [658] Treatment of Localized Prostate Cancer: A Survival Analysis Using SEER-Medicare Data

Yu-Ning Wong*, Fei Wan, Nandita Mitra, Russell Localio, Chantal Montagnet, Gary Hudes, Katrina Armstrong, Philadelphia, PA.

Introduction and Objective: Prostate specific antigen screening has led to an increase in the diagnosis (DX) and treatment (TR) of localized prostate cancer (LPC), yet there is little randomized data comparing TR to observation (OBS).
Methods: We used Surveillance, Epidemiology and End Results -Medicare data to create a cohort of men aged 65-80 years old diagnosed with LPC from 4/1991-9/1999 who were alive for at least 1 year post-DX. Overall Survival (OS) was defined as the interval from DX to Medicare date of death or end of the study (10/15/2003) if the man was still alive. Tumors were characterized by size (T1-T2a vs T2b-T2c) and grade (well vs moderately differentiated). Poorly differentiated tumors were excluded. TR was defined as having claims for radical prostatectomy (RP) or radiation (RAD) +/- hormone therapy (HT) within 6 months of DX. Men without claims for RP or RAD were considered OBS. Men with HT alone were not included. We used propensity scores to control for known predictors of receiving TR (size, grade, age, year of DX, demographics, co-morbidities). We used COX proportional hazard models to estimate the effective of TR on OS. We performed sensitivity analyses to estimate the possible effects of an unknown confounder. Results: The final cohort used consisted of 49,375 men with a median age at DX of 72. Median survival for OBS was 133 months (11 years). More than 50% of TR was alive at the end of the study period. Results of the cohort and subgroups are listed in below. For the full cohort, there was an interaction between size and TR and grade and TR (p<.0005). Sensitivity analysis of the full cohort found that an unknown confounder would need to be unequally distributed between TR and OBS or increase the HR for death by at least 50% in both groups to eliminate the advantage of TR.
Conclusions: This large population based study demonstrates a survival advantage for TR with either RP or RAD compared to OBS in men with LPC. In the absence of randomized studies comparing RP and RAD, eligible men should be considered for both.
[table1][figure1]

Discussed Poster: Prostate Cancer: Localized (I) (9:00 AM-12:00 PM)