Chemotherapy use and adoption of new agents is affected by age and comorbidities in patients with metastatic colorectal cancer

BACKGROUND: The treatment of metastatic colorectal cancer (mCRC) has changed substantially in the last 2 decades, but to the authors' knowledge, the effect of age and comorbidities on chemotherapy use has not been well studied to date. METHODS: Patients with mCRC who were being treated with 5-fluorouracil (5-FU)-based chemotherapy between January 1995 to December 2009 were studied using the LifeLink Health Plan Claims Database. The cohort was divided into older (aged >70 years) and younger (aged ≤70 years) patients. The Charlson Comorbidity Index (CCI) was used to assess comorbidity burden. The Wilcoxon and chi-square tests were used in univariate and logistic regression in multivariate analyses. RESULTS: A total of 16,087 patients were identified, with 24% of the patients who were receiving chemotherapy being aged >70 years. The percentage of patients with a CCI >1 receiving chemotherapy increased over time (14% in 1996 vs 40% after 2004; P<.05). Older patients were less likely to receive treatment with >2 agents compared with younger patients (15% vs.22% and 11% vs.16%, respectively, in 2003 and 2009; P<.001). After approval by the US Food and Drug Administration in 1998, the use of irinotecan was lower in older compared with younger patients, a difference that resolved by 2002 (15% vs 38% [P<.05]; 62% in both groups [P =.9], respectively). Similarly, oxaliplatin was used more frequently in younger patients in 2003 (22% vs 15%; P<.05), with a decrease in this difference noted by 2009 (64% vs 60%; P =.95). On multivariate analysis, older age (odds ratio, 0.65; P<.001) and a CCI >1 (odds ratio, 0.84; P<.001) were found to be associated with a lower likelihood of receiving combination chemotherapy. CONCLUSIONS: In this commercially insured population, the percentage of older patients treated for mCRC was low, and the rate of chemotherapy adoption was found to lag behind that of younger patients. However, the percentage of older patients with comorbidities receiving therapy increased over time. Cancer 2016;122:3191–8.