Oxaliplatin plus fluoropyrimidines as adjuvant therapy for colon cancer in older patients: A subgroup analysis from the TOSCA trial.

BACKGROUND

Previous studies on oxaliplatin and fluoropyrimidines as adjuvant therapy in older patients with stage III colon cancer (CC) produced conflicting results.

PATIENTS AND METHODS

We assessed the impact of age on time to tumour recurrence (TTR), disease-free survival (DFS), cancer-specific survival (CSS), and overall survival (OS) in 2360 patients with stage III CC (1667 aged <70 years and 693 ≥ 70 years) randomised to receive 3 or 6 months of FOLFOX or CAPOX within the frame of the phase III, TOSCA study.

RESULTS

Older patients compared with younger ones presented more frequently an Eastern Cooperative Oncology Group performance status equal to 1 (10.5% vs 3.3%, p < 0.001), a greater number of right-sided tumours (40.9% vs 26.6%, p < 0.001), and were at higher clinical risk (37.2% vs 33.2%, p = 0.062). The treatments were almost identical in the two cohorts (p = 0.965). We found a greater proportion of dose reductions (46.7% vs 41.4%, p = 0.018), treatment interruptions (26.1% vs 19.3%, p < 0.001) and a higher proportion of recurrences (24.2% vs 20.3%, p = 0.033) in the older patients. The multivariable analysis of the TTR did not indicate a statistically significant effect of age (hazard ratio [HR]: 1.19; 95% confidence interval [CI]: 0.98-1.44; p = 0.082). The HR comparing older with younger patients was 1.34 (95% CI: 1.12-1.59; p = 0.001) for DFS, 1.58 (95% CI: 1.26-1.99; p < 0.001) for OS, and 1.28 (95% CI: 0.96-1.70; p = 0.089) for CSS.

CONCLUSIONS

Worse prognostic factors and reduced treatment compliance have a negative impact on the efficacy of oxaliplatin-based adjuvant therapy in older patients.