A prospective cohort study of patient-reported vomiting, retching, nausea and antiemetic use during neoadjuvant long-course radiation therapy and concurrent 5-fluorouracil-based chemotherapy for rectal adenocarcinoma

Background and purpose Antiemetic guidelines suggest daily prophylaxis with a serotonin3 receptor antagonist (5-HT3RA) as an option for patients receiving long-course neoadjuvant radiation therapy and concurrent 5-fluorouracil-based chemotherapy for rectal cancer, despite the risks that 5-HT3RA-induced constipation may pose. We explored the incidence of patient-reported vomiting, retching, nausea and antiemetic intake among patients in this setting to determine if these risks are justified.Materials and methods We carried out a single-centre non-randomised prospective cohort study of adult patients receiving long-course neoadjuvant radiation therapy and concurrent 5-fluorouracil-based chemotherapy for rectal adenocarcinoma. Patients recorded symptoms and medication intake daily until 7 days following treatment completion.Results From 33 evaluable patients, we collected 1407 days of patient-reported data. Vomiting was reported by 7 patients (21%), retching by 5(15%) and nausea by 21(64%). No patients were administered prophylactic antiemetics. The median number of days with vomiting was 2, and the cumulative number of days for all affected patients was 22 (1.6% of 1407 evaluable days). There were no differences in PTV or small bowel loop V15Gy, V45Gy and V50Gy volumes between patients that did and did not vomit.Conclusions The cumulative incidence of days with vomiting was only 1.6%. 5-HT3RA prophylaxis during long-course neoadjuvant treatment seems unnecessary.