Adjuvant chemotherapy for elderly patients with colorectal cancer: a single-centre observational study in Japan

Adjuvant chemotherapy improves the prognosis of patients with colorectal cancer (CRC) following radical resection. The aim of the present study is to review appropriate chemotherapeutic regimens for elderly patients. We examined 1138 Japanese patients who were operated for high-risk stage II or stage III CRC between July 2010 and June 2021 at our hospital. Patients were divided according to an age of 70 years. The efficacy of adjuvant therapy was analyzed in association with age and adjuvant chemotherapeutic regimens. A total of 507 patients (45%) were ≥70 years old. They were less likely to receive adjuvant chemotherapy (<i>p</i> &lt; 0.001) or palliative chemotherapy after recurrence (<i>p</i> &lt; 0.001) than patients aged &lt;70 years. Cancer-specific survival (CSS) in stage III CRC patients was longer in the &lt;70 years group than in the ≥70 years group (<i>p</i> = 0.006); however, CSS by regimens did not significantly differ between these groups. Adjuvant chemotherapy was associated with the longer relapse-free survival of stage III CRC patients in the &lt;70 years group (<i>p</i> = 0.005). Although adjuvant chemotherapy was associated with a favourable CSS regardless of age, the implementation rate of adjuvant chemotherapy for elderly CRC patients was low, which may explain shorter CSS in stage III CRC patients the ≥70 years group than in the &lt;70 years group.