Background: Trials have stringent inclusion and exclusion criteria to maintain internal validity. However, study findings are often applied to patients in routine practice who do not meet CTEC. Our aim was to characterize the outcomes and magnitude of treatment benefit in these patients. Methods: Patients diagnosed with stage III colon cancer from 2006 and 2008, referred to 1 of 5 regional cancer centers in British Columbia, and assessed for adjuvant chemotherapy (AC) within 12 weeks of surgery were analyzed. Patients were considered trial-eligible (TE) if aged 18 to 79 years, ECOG 0/1, CEA <10, did not receive prior chemotherapy or radiation, and had adequate blood counts and normal cardiac, liver and kidney function. All other patients were deemed trial-ineligible (TI). Results: A total of 820 patients were identified: median age was 69 years (range 60-76), 423 (52%) were men, 365 (45%) were ECOG 0/1 and 592 (72%) received AC. Among patients treated with AC, 370 (63%) were TE and 222 (37%) were TI. Compared to TI patients, those who were TE were younger (63 vs. 70 years, p < 0.01) and more likely to receive combination regimens rather than single agent AC (56 vs. 33%, p < 0.01). Outcomes were significantly different among patients who were TE, TI, and those who did not receive AC (Table). In multivariate analyses that adjusted for known prognostic factors such as age, ECOG and T and N stages, both TI patients and those not treated with AC had worse outcomes than TE patients (HR for colon cancer death 1.32, 95%CI 0.86-2.02 and 2.77, 95%CI 1.92-3.99, respectively, p trend < 0.01; HR for all cause death 1.24, 95%CI 0.85-1.80 and 2.95, 95%CI 2.17-4.00, respectively, p trend < 0.01). Conclusions: In this population-based cohort, colon cancer patients who did not fit CTEC were frequently treated with AC. Outcomes in this TI group were inferior to those in the TE group, but they were better than the subset that did not receive AC. Broadening CTEC to include a segment of the TI population should be considered as there appears to be benefit in selected individuals.

Abbreviations: CSS, cancer-specific survival; OS, overall survival; TE, trial-eligible; TI, trial-ineligible; AC, adjuvant chemotherapy.