Cost-Effectiveness of Second-Line Chemotherapy/Biologics among Elderly Metastatic Colon Cancer Patients

Introduction Advancements in chemotherapy treatment have improved the clinical management of metastatic colon cancer (mCC) patients. An increasing number of elderly mCC patients receive various combinations of regimens in second-line chemotherapy/biologics treatment (Tx2) after first-line treatment (Tx1) to prolong survival and/or palliate symptoms, but these regimens have higher costs. This analysis investigated the survival benefit and incremental cost associated with Tx2 among elderly mCC patients. Methods Elderly (aged ≥66 years) SEER-Medicare patients diagnosed with mCC in 2003–2007 were identified and followed until death or the end of 2009. Cox regression and partitioned least squares regression were utilized to obtain the survival benefit and incremental cost associated with Tx2 within a 5-year study period. A time-varying model was used to reduce bias due to sequential ordering of Tx1 and Tx2. The regressions controlled for patient demographic characteristics, clinical variables, and a proxy for poor performance. Bootstrapping was used to generate 95% confidence intervals (CI). Results Of the 3,266 elderly mCC patients who received Tx1, 2,744 (84%) died within the observation period; 1,440 (44%) received Tx2. The survival benefit associated with receipt of Tx2 was 0.33 years (95% CI 0.19–0.43), and the associated incremental cost was $40,888 (95% CI 3,044–44,324). The incremental cost-effectiveness ratio (ICER) for Tx2 was $123,903 per life year gained (95% CI 9,600–216,082). Conclusion The estimated survival benefit of receiving second-line chemotherapy/biologics was about 4 months, which is consistent with evidence from clinical trials. This improved survival was associated with an ICER that exceeds the traditional threshold.