Background: CAPOX regimen is a standard option in stage III adjuvant colon cancer. Gastrointestinal toxicity is well described with fluoropyrimidine regimens and can be life-threatening. Identification of risk factors associated with severe gastrointestinal toxicity may help clinicians when choosing the adjuvant regimen.

Materials and Methods: We retrospectively analysed 61 patients treated with adjuvant CAPOX. Our primary objective was to estimate the incidence of severe chemotherapy-induced enterocolitis among patients treated with CAPOX. A secondary objective was to describe the main demographic and clinical characteristics of these patients. A univariate logistic regression was performed to estimate the odds ratio (OR) with a 95% CI to identify a predictor for severe enterocolitis.

Results: Grade 3 diarrhoea was reported in 10 patients (16.3%). Admissions to hospital due to toxicity occurred in nine cases. Reasons for hospitalisation were severe enterocolitis in eight cases (13.1%) and rectal bleeding plus thrombocytopenia in one case. Age > 70 years (OR 9.6; 95% CI 1.81–50.6; p = 0.008), primary surgery involving right/transverse colon (OR 16.8; 95% CI 2.88–98.8; p = 0.002) and Angiotensin II Receptor Blocker (ARB) use (OR 8.14; 95% CI 1.64–40.3; p = 0.010) were associated with severe enterocolitis.

Conclusion: Our data showed that adjuvant CAPOX induced severe enterocolitis in 13.1% of patients. In addition, we found that advanced age, right colectomy and concurrent use of ARB were statistically associated with these events. Awareness of these factors could be easily incorporated into the treatment decision and patient orientation.