Survival outcomes of patients with stage III colorectal cancer aged ≥80 years who underwent curative resection: The HiSCO-04 prospective cohort study

Abstract Background The efficacy of adjuvant chemotherapy in elderly patients aged ≥ 80 years with stage III colorectal cancer (CRC) who have undergone curative resection remains unclear. In parallel with a multicenter prospective phase II trial evaluating the efficacy and safety of UFT/LV as adjuvant chemotherapy (HiSCO-03), we conducted a prospective observational study of these patients to assess survival outcomes, including patients ineligible for chemotherapy.Methods This multi-institutional prospective cohort study included 17 institutions in Hiroshima, Japan. Patients aged ≥ 80 years with stage III CRC who underwent curative resection were enrolled. The primary endpoint was 3-year disease-free survival (DFS), and the secondary endpoints were 3-year overall survival (OS) and relapse-free survival (RFS). Propensity score matching was used to assess the effect of adjuvant chemotherapy on survival outcomes.Results A total of 214 patients were analyzed between 2013 and 2018. There were 99 males and 115 females with a median age of 84 years (range: 80–101 years). Recurrence occurred in 58 patients and secondary cancers were observed in 17 patients. The 3-year DFS, OS, and RFS rates were 63.3%, 76.9%, and 62.9%, respectively. Adjuvant chemotherapy was administered to 64 patients with a completion rate of 53%. In a study of 80 patients that adjusted for background factors using propensity score matching, patients who completed the planned treatment showed improved DFS.Conclusions Completion of adjuvant chemotherapy may improve the prognosis of CRC patients aged ≥ 80 years, although the number of patients who would benefit from it is limited.