BACKGROUND: Elderly patients with primary colorectal cancer (CRC) are less frequently treated with adjuvant chemotherapy than younger patients due to concerns regarding toxicity and efficiency. We investigated how age, performance status (PS) and comorbidity influence treatment outcomes.

PATIENTS AND METHODS: A retrospective single-centre study of 529 patients with stages II-III CRC treated with adjuvant chemotherapy (5-fluorouracil/capecitabine+/÷oxaliplatin) from 2001 to 2011 at Herlev Hospital, Denmark. Baseline characteristics, chemotherapy and outcome were analysed with respect to age after adjusting for PS and comorbidity.

RESULTS: Elderly patients (>70 years) had significantly more comorbidity (p<0.001) and poorer PS (p=0.001) than younger patients. Elderly were more frequently treated with single-agent therapy (p=0.001) and at lower initial dose (p<0.001). There was no age-dependent difference in 3-year disease-free survival (DFS; HR 1.09, 95% CI 0.80 to 1.47, p=0.59), in grade 3-5 toxicity (29% vs 28%, p=0.86) or in 10-year CRC mortality (28%, HR 1.07, p=0.71). In elderly patients, a reduction in chemotherapy dose intensity compared with full dose had no impact on DFS or CRC mortality. Elderly patients receiving <50% of planned cycles had shorter DFS (HR=1.78, p=0.020) and higher CRC mortality (HR=2.17, p=0.027) than elderly receiving all cycles. Poor PS in younger and elderly patients was related to shorter DFS (HR=1.95, p=0.002; HR=1.6, p=0.035, respectively) and overall survival (OS; HR=2.28, p<0.001; HR=2.03, p=0.002). Comorbidity in younger patients was significantly related to shorter DFS (HR 2.72, p<0.001), OS (HR 3.16, p<0.001) and higher CRC mortality (HR 2.70, p=0.001).

CONCLUSIONS: Choice of regimen, primary dose reduction and given dose intensity in patients treated with adjuvant chemotherapy for CRC were highly dependent on age. However, age had no impact on DFS and CRC mortality. Comorbidity in younger patients and PS in all patients were associated with shorter DFS and higher CRC mortality.