The benefit of adjuvant chemotherapy in elderly patients with stage III colorectal cancer is independent of age and comorbidity

OBJECTIVES: To determine the combined effect of age and comorbidity on receipt of chemotherapy and its impact on survival in elderly patients with stage III colorectal cancer (CRC). MATERIALS AND METHODS: All patients over age 65 with Stage III CRC diagnosed 1996-2006 were identified from the Barnes-Jewish Hospital Oncology Data Services registry. An age/comorbidity staging system was created using the ACE-27 comorbidity index and data from both Stage II and III CRC. The staging system was then applied to patients with Stage III CRC. Odds of receiving chemotherapy were calculated, and survival analyses determined the impact of chemotherapy on overall survival in each age/comorbidity stage. RESULTS: 435 patients with Stage III CRC were evaluated [median age 75 years (range 65-99)]. Advancing age/comorbidity stage (Alpha, Beta, Gamma) was associated with decreasing odds of receiving chemotherapy for Stage III CRC [Odds Ratio 0.83 (95% CI, 0.51-1.35) for Beta and 0.14 (95% CI, 0.08-0.24) for Gamma, compared to Alpha]. Chemotherapy was associated with lower risk of death in each of the age/comorbidity stages, compared to those who underwent surgery only. The hazard ratio for death in patients who did not receive chemotherapy, relative to those who did, within each age/comorbidity stage was 1.8 [95%CI 1.06-3.06] for Alpha, 2.24 [95%CI 1.38-3.63] for Beta and 2.10 [95% CI 1.23-3.57] for Gamma. CONCLUSION: While stage III CRC patients with increasing age and comorbidity are less likely to receive chemotherapy, receipt of chemotherapy is associated with a lower risk of death.