Observation versus treatment among men with favorable risk prostate cancer in a community-based integrated health care system: a retrospective cohort study.

BACKGROUND: The objective of this study was to describe overall survival and the management of men with favorable risk prostate cancer (PCa) within a large community-based health care system in the United States.

METHODS: A retrospective cohort study was conducted using linked electronic health records from men aged ≥40 years with favorable risk PCa (T1 or 2, PSA ≤15, Gleason ≤7 [3 + 4]) diagnosed between January 2005 and October 2013. Cohorts were defined as receiving any treatment (IMT) or no treatment (OBS) within 6 months after index PCa diagnosis. Cohorts' characteristics were compared between OBS and IMT; monitoring patterns were reported for OBS within the first 18 and 24 months. Cox Proportional Hazards models were used for multivariate analysis of overall survival.

RESULTS: A total of 1425 men met the inclusion criteria (OBS 362; IMT 1063). The proportion of men managed with OBS increased from 20% (2005) to 35% (2013). The OBS group was older (65.6 vs 62.8 years, p < 0.01), had higher Charlson comorbidity index scores (CCI ≥2, 21.5% vs 12.2%, p < 0.01), and had a higher proportion of low-risk PCa (65.2% vs 55.0%, p < 0.01). For the OBS cohort, 181 of the men (50%) eventually received treatment. Among those remaining on OBS for ≥24 months (N = 166), 88.6% had ≥1 follow-up PSA test and 26.5% received ≥1 follow-up biopsy within the 24 months. The unadjusted mortality rate was higher for OBS compared with IMT (2.7 vs 1.3/100 person-years [py]; p < 0.001). After multivariate adjustment, there was no significant difference in all-cause mortality between OBS and IMT groups (HR 0.73, p = 0.138).

CONCLUSIONS: Use of OBS management increased over the 10-year study period. Men in the OBS cohort had a higher proportion of low-risk PCa. No differences were observed in overall survival between the two groups after adjustment of covariates. These data provide insights into how favorable risk PCa was managed in a community setting.