OBJECTIVES

The benefits of adjuvant chemotherapy for stage III colon cancer include reducing the likelihood of disease recurrence and increasing the cure rate. However, there is no general agreement that adjuvant chemotherapy should be offered to the elderly since they may have shorter life expectancy and comorbid conditions. In this study, we aim to determine whether adjuvant chemotherapy improves survival in patients older than 75 years.

METHODS

This is a retrospective cohort study using the Taiwan National Health Insurance Research Database. Patients must meet the following inclusion criteria:(1) Diagnosis of stage III colon cancer in 2009 and 2010. (2)Age greater than 75 at diagnosis. (3)Operation performed within six months after diagnosis. All included patients were divided into three groups: no-treatment, 5-FU based treatment, and oxaliplatin-based treatment groups. The diagnosis date was defined as the index date. Our study outcome was all-cancer related death. The last follow-up time was 2016/12/31. Survival analysis and cox regression adjusted with propensity score weighting and competing risk were conducted to analyze the outcome in different groups.

RESULTS

A total of 974 patients were enrolled, of whom 266 (27.5%) were not treated after operation. Compared to the no-treatment group, patients treated with either 5-FU based or oxaliplatin-based chemotherapy had better cancer-related survival (median 2.3 months for no-treatment group; median not yet calculable by study end for both treatment groups due to extended survival) Multivariate analysis revealed adjuvant chemotherapy was an independent predictor of better cancer-related survival (adjusted hazard ratio[aHR]=0.508, 95% confidence interval[CI]:0.432-0.598 for 5-FU based; aHR=0.427, 95% CI: 0.334-0.545 for oxaliplatin-based). Cancer-related survival did not differ between the two chemotherapy regimens (aHR=0.935, 95% CI:0.689-1.269).

CONCLUSIONS

Patients older than 75 years receiving adjuvant chemotherapy had better survival outcomes than those who did not. Age is not an excuse to withdraw adjuvant chemotherapy in the elderly who are eligible for tumor resection.