Metastatic colorectal cancer is a type of cancer of the colon that has spread beyond the colon to other organs. Though the prevalence of colon cancer is higher in older or vulnerable patients, they are seldom involved in trials. This study aims to compare full-dose monotherapy and reduced-dose combination chemotherapy in older vulnerable patients.

In this open-label, randomized, phase-2 trial, a total of 160 patients aged 70 years or older with previously untreated metastatic colorectal cancer were included. The patients were randomized in a 1:1 ratio to full-dose monotherapy followed by second-line treatment with irinotecan (n=83) or reduced-dose combination chemotherapy followed by second-line treatment with monotherapy (n=77). The primary outcome of the study was progression-free survival.

During the median follow-up of 23.8 months, 81 patients (98%) in the full-dose monotherapy group and 71 (92%) in the reduced-dose combination chemotherapy group had died or progressed. The median progression-free survival was 6.2 months in the reduced-dose combination group, as compared with 5.3 months in the full-dose monotherapy group. The incidence of adverse events was more prevalent in the full-dose monotherapy group (62%).

The research concluded that reduced-dose combination chemotherapy was safer, well-tolerated, and more effective than full-dose monotherapy in patients with metastatic colorectal cancer.