Eligibility of Real-World Patients With Stage II and III Colon Cancer for Adjuvant Chemotherapy Trials

Abstract

Introduction: The results of adjuvant chemotherapy trials in stage II and III colon cancer are often extrapolated to real-world patients. This study was conducted to determine the proportion of real-world patients with stage II/III colon cancer who would be eligible for adjuvant chemotherapy trials and to compare the outcomes among eligible versus ineligible patients.

Patients and methods: We identified all patients diagnosed with stage II/III colon cancer between 2004 and 2015 from a large province in Canada. Patients meeting any one of the following criteria were considered ineligible: age > 75 years, anemia, comorbid conditions (heart disease, uncontrolled diabetes, kidney disease, liver disease), and a history of malignancy or immunosuppression. Cox regression models were constructed to determine the factors predicting overall and cancer-specific survival.

Results: A total of 7841 patients with stage II/III colon cancer were identified, of whom 52.0% were men and median age at diagnosis was 71 years. Approximately 58.6% of patients were deemed trial ineligible; the most common reasons for ineligibility included advanced age (36.2%), renal dysfunction (26.9%), and cardiac disease (17.4%). In the real-world setting, 54.0% of eligible patients received adjuvant chemotherapy compared to 23.2% of ineligible patients (odds ratio, 3.89; 95% confidence interval, 3.53-4.28; P < .0001). The 5-year overall and cancer-specific survival of trial-ineligible patients who received adjuvant chemotherapy was significantly better than those treated with surgery alone.

Conclusion: The eligibility criteria of adjuvant chemotherapy trials in colon cancer should be broadened to be more representative of real-world patients.

Keywords: Clinical trial eligibility; Colon cancer; Colorectal cancer; Exclusion criteria; Inclusion criteria.