Survival benefits and trends in use of adjuvant therapy among elderly stage II and III rectal cancer patients in the general population.

Background: This study examined elderly stage II and III rectal cancer patients' adjuvant chemoradiation therapy adherence, trends in adherence over time, and the relation of levels of adherence to mortality.

Methods: The authors studied 2886 stage II and III rectal cancer patients who had surgical resection and who appeared in 1992-1999 linked SEER-Medicare claims data. The authors compared measures of adjuvant radiation and chemotherapy receipt and completion between stage II and III patients. Adjusted risk of cancer-related 5-year mortality was calculated by multivariate logistic regression for different levels of chemoradiation adherence among stage II and III patients.

Results: Of the 2886 patients, 45.4% received both adjuvant radiation and chemotherapy. Stage III patients were more likely to receive chemoradiation than stage II patients. The receipt of chemoradiation by stage II patients increased significantly from 1992 to 1999. Stage III patients were more likely to complete radiation therapy (96.6%), chemotherapy (68.2%), and both modalities (67.5%) than stage II patients (91.5%, 49.8%, 47.6%, respectively). Only a complete course of both radiation and chemotherapy for both stage II (relative risk [RR] 0.74; 95% CI, 0.54, 0.97) and III (RR 0.80; 95% CI, 0.65, 0.96) decreased the adjusted 5-year cancer mortality risk compared with counterparts with no adjuvant therapy.

Conclusions: Even though stage II rectal cancer patients were less likely than stage III patients to receive and complete adjuvant chemoradiation, both patient groups in the general population had lower cancer-related mortality if they completed chemoradiation. These patients deserve support and encouragement to complete treatment.