Matched-cohort analysis of patients with prostate cancer followed with observation or treated with three-dimensional conformal radiation therapy

OBJECTIVES: To compare the outcome of similar patients with prostate cancer treated by either observation or three-dimensional conformal radiation therapy (3-DCRT). PATIENTS AND METHODS: The study included 69 patients with nonmetastatic prostate cancer who were observed only; the indications included indolent disease, significant medical comorbidities and refusal of treatment. Of these, 62 patients had palpable T1-T2a and seven T2b-T3a disease, a median Gleason score of 6 and a median initial prostate-specific antigen (PSA) level of 5.3 ng/mL. A matched-cohort analysis of 69 patients, based on palpation T category, Gleason score and initial PSA, was used to compare the outcome between the observation and 3-DCRT groups. The median radiation dose for latter was 72 Gy. RESULTS: The median follow-up for the observed patients was 49 months. The 5- and 8-year actuarial rates of freedom from distant metastases were 100% and 93%, respectively, and the actuarial overall survival rates 94% and 73%, respectively. Seven observed patients had local disease progression on physical examination. Four patients who initially were observed received radiation therapy later for a rising PSA and/or local disease progression. For the 69 matched 3-DCRT patients, the overall 5-year rate for no biochemically evident disease was 74%. The respective 5- and 8-year actuarial rates of freedom from distant metastases were 95% and 95%, and actuarial overall survival rates 95% and 75%. There were no significant differences in distant metastasis and overall survival rates between the groups, and no deaths from prostate cancer in either group. CONCLUSIONS: Observation is a reasonable alternative to treatment in selected patients. During the 5-year follow-up the progression rates were relatively low, and there was no difference in distant metastasis or overall survival between the groups. As the follow-up was short a longer follow-up is needed to determine whether the outcome of those patients who chose observation will remain comparable to that in those undergoing immediate 3-DCRT.