Variation in Delayed Time to Adjuvant Chemotherapy and Disease-Specific Survival in Stage III Colon Cancer Patients.

Abstract

There is a paucity of literature quantifying the extent to which time to adjuvant chemotherapy for stage III colon cancer patients varies between individual surgeons, medical oncologists, and hospitals. A retrospective cohort study was conducted by merging the New York State Cancer Registry with the Statewide Planning & Research Cooperative System and Medicare claims to identify stage III colon cancer patients from 2004 to 2009 who underwent resection and received adjuvant chemotherapy. Multilevel logistic regression models characterized variation in delayed time to adjuvant chemotherapy (>8weeks vs.≤8weeks). Multilevel competing-risks Cox proportional hazards models assessed the effect of delayed time to adjuvant chemotherapy on disease-specific survival. The proportion of delayed time to adjuvant chemotherapy was 36% in 1133 patients treated by 516 surgeons and 351 medical oncologists at 163 hospitals. After controlling for case-mix, the majority of the clustering variation (72%) in delayed time to adjuvant chemotherapy is attributed to differences between medical oncologists. Risk-adjusted surgeon-specific, medical oncologist-specific, and hospital-specific probabilities of delayed time to adjuvant chemotherapy ranged from 30 to 38, 17 to 59, and 27 to 43%, respectively. Delayed time to adjuvant chemotherapy was associated with disease-specific survival (hazard ratio [HR]1.24, 95% confidence interval [CI]1.07-1.45). These findings suggest there is substantial variation in time to adjuvant chemotherapy among stage III colon cancer patients. Reasons for delays may be due to system factors that influence individual providers to make varying decisions on the time of initiation. Future research should identify what these factors may be and how to address them to promote better delivery of care.