Does primary androgen-deprivation therapy delay the receipt of secondary cancer therapy for localized prostate cancer?

BACKGROUND: Despite evidence that shows no survival advantage, many older patients receive primary androgen-deprivation therapy (PADT) shortly after the diagnosis of localized prostate cancer (PCa).
OBJECTIVE: This study evaluates whether the early use of PADT affects the subsequent receipt of additional palliative cancer treatments such as chemotherapy, palliative radiation therapy, or intervention for spinal cord compression or bladder outlet obstruction. DESIGN, SETTING, AND PARTICIPANTS: This longitudinal population-based cohort study consists of Medicare patients aged ≥ 66 yr diagnosed with localized PCa from 1992 to 2006 in areas covered by the Surveillance Epidemiology and End Results (SEER) program. SEER-Medicare linked data through 2009 were used to identify the use of PADT and palliative cancer therapy. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Instrumental variable analysis methods were used to minimize confounding effects. Confidence intervals were derived from the bootstrap estimates. RESULTS AND LIMITATIONS: This study includes 29 775 men who did not receive local therapy for T1-T2 PCa within the first year of cancer diagnosis. Among low-risk patients (Gleason score 2-7 in 1992-2002 and Gleason score 2-6 in 2003-2006) with a median age of 78 yr and a median follow-up of 10.3 yr, PADT was associated with a 25% higher use of chemotherapy (hazard ratio [HR]: 1.25; 95% confidence interval [CI], 1.08-1.44) and a borderline higher use of any palliative cancer treatment (HR: 1.07; 95% CI, 0.97-1.19) within 10 yr of diagnosis in regions with high PADT use compared with regions with low PADT use. Because this study was limited to men >65 yr, the results may not be applicable to younger patients.
CONCLUSIONS: Early treatment of low-risk, localized PCa with PADT does not delay the receipt of subsequent palliative therapies and is associated with an increased use of chemotherapy.