Time to ADT and chemotherapy initiation for treatment of metastatic prostate cancer (mPC).
41 Background: ADT and chemotherapy use in men with mPC may differ across regions in community practice. The extent of variation could indicate whether men with mPC have appropriate access to effective treatments. Methods: We identified 16,024 men diagnosed with mPC in the Surveillance, Epidemiology, and End Results (SEER) database from 2000-2005 linked to their Medicare claims. Patients were excluded if they had a second cancer or disenrolled from Medicare Parts A or B (n=6,155), or failed to initiate therapy with ADT (n=3,400). We identified demographic and clinical information from SEER and treatments and comorbidities from J-codes and ICD-9 codes in the Medicare claims. We used regression models to estimate the probability of advancement to chemotherapy, the time from diagnosis to first ADT use, and time from first ADT to chemotherapy. Then the patient-level predicted results from these models were used to generate summary statistics by hospital service area (HSA). Results: There were 6,469 patients remaining after exclusion who were treated with ADT, and 1,198 of those received chemotherapy (19%). The median age was 76 years old, most were white (77%), married (62%), and 50% had 1 other major comorbidity (most frequent was diabetes, 21%). Men who were younger, married, with fewer comorbidities, and higher Gleason scores were statistically more likely to both receive chemotherapy and use it earlier. After adjusting for clinical and sociodemographic factors, the average time to ADT by referral region was 2.7 months but varied from 1.3 to 5.6; probability of progression to chemotherapy averaged 19% but varied from 6% to 30%, and the time from first ADT to chemotherapy averaged 19.7 months but varied from 12.9 to 25.7 months. The difference in time to ADT between regions in the 10th and 90th percentiles of use was 2.6 months, whereas for chemotherapy initiation, it was 12.4 months. Conclusions: Our results suggest that living in different parts of the country has a substantial impact on how clinically similar patients are treated. There was substantial variation across regions in use of and time to initiation of chemotherapy for men with mPC, but not in ADT use.