Abstract
PURPOSE: In 2004, the US Food and Drug Administration approved bevacizumab and oxaliplatin for use in metastatic colon cancer and oxaliplatin for localized colon cancer. We investigated the diffusion and predictors of use of these medications in the year after approval. PATIENTS AND METHODS: We used the Surveillance, Epidemiology, and End Results-Medicare database to identify patients older than 65 years diagnosed with stages III and IV colon cancer in 2005. Characteristics of the treating oncologists were identified using the American Medical Association database. We used logistic regression and generalized estimating equations to analyze factors associated with bevacizumab and oxaliplatin use. RESULTS: Among 1,547 patients with stage III colon cancer who had claims submitted by oncologists, 801 (51.8%) received adjuvant chemotherapy, and of those, 432 (54.1%) received oxaliplatin, whereas 54 (6.7%) received off-label bevacizumab. Among 859 patients with stage IV disease who saw oncologists, 435 (50.6%) received chemotherapy, and of those, 310 (71.3%) received bevacizumab, 289 (66.4%) received oxaliplatin, and 357 (82.1%) received oxaliplatin and/or irinotecan. Older patient age and more comorbidities were associated with nonreceipt of oxaliplatin for stage III disease and oxaliplatin and/or irinotecan for stage IV disease. Having a physician who graduated medical school after 1975 predicted receipt of both adjuvant oxaliplatin (odds ratio [OR], 1.65; 95% CI, 1.11 to 2.45) and oxaliplatin and/or irinotecan for stage IV disease (OR, 2.43; 95% CI, 1.47 to 4.01). None of the factors analyzed predicted bevacizumab receipt. CONCLUSION: Uptake of new chemotherapy drugs for patients diagnosed with stages III and IV colon cancer in 2005 was rapid. Physician characteristics were consistently associated with this uptake.