Recurrence-free survival in patients with stage III colorectal cancer who did or did not complete adjuvant chemotherapy.

PURPOSE: To evaluate the impact of adjuvant chemotherapy continuity on the recurrence-free survival in real-world patients with stage III colorectal cancer. METHODS: We retrospectively analyzed 281 patients with pathologic stage III colorectal cancer who underwent curative resection at two institutions in Japan. Patients were classified into three groups according to their adjuvant chemotherapy status: completion, discontinuation, or no initiation. Recurrence-free survival was compared between the groups. Factors associated with treatment discontinuation were assessed using a multivariable logistic regression analysis. RESULTS: Among the 159 patients who initiated adjuvant chemotherapy, 116 (73.0%) completed the planned course. Completion was associated with a significantly better recurrence-free survival than discontinuation (5-year recurrence-free survival 77.6% vs. 56.5%, p=0.013). Recurrence-free survival in the discontinuation group was similar to that in patients without chemotherapy (56.5% vs. 55.8%, p=0.498). Severe adverse events (CTCAE grade 3 or higher) were independently associated with treatment discontinuation (odds ratio 6.658, 95% confidence interval 2.807-16.740, p<0.001). Most discontinuations occurred within the first three months (78.9%). In patients who initiated chemotherapy, discontinuation was independently associated with a poorer recurrence-free survival (RFS). CONCLUSIONS: Completion of adjuvant chemotherapy was associated with an improved recurrence-free survival, whereas early discontinuation, largely driven by severe toxicity, was associated with inferior survival outcomes.