The association of comorbidities with administration of adjuvant chemotherapy in stage III colon cancer patients: a systematic review and meta-analysis

BACKGROUND: Chemotherapy is an established treatment for stage III colon cancer cases. Older age is known to be associated with less chemotherapy use in these patients, but there might be other relevant factors besides age that influence treatment administration. We summarized evidence on associations between comorbidity and adjuvant chemotherapy administration in stage III colon cancer patients in a systematic review and meta-analysis. METHODS: We searched the PubMed and Web of Science databases up to 2 June 2020 for studies on comorbidities and chemotherapy use in patients with stage III colon cancer. Summary odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using random-effects models. Subgroup analyses according to year of colon cancer diagnosis, timing of comorbidity assessment, and geographical region were also conducted. RESULTS: Thirty-three studies were included in this review, including 219,406 stage III colon cancer patients overall. Chemotherapy administration was 60.9% (95% CI: 56.9% to 64.9%), increasing from 57.1% before 2001 to 66.3% after 2010. There were inverse associations between comorbidities and chemotherapy administration. Compared with patients with Charlson comorbidity score 0, those with scores 1 (OR = 0.79, 95% CI = 0.72–0.87) and 2+ (OR = 0.49, 95% CI = 0.42–0.56) received chemotherapy less often. Among comorbidities, the strongest predictors of chemotherapy non-use were dementia (OR = 0.37, 95% CI = 0.33–0.54), followed by heart failure (OR = 0.44, 95% CI = 0.28–0.70) and stroke (OR = 0.56, 95% CI = 0.38–0.81). CONCLUSIONS: Merely 60% of stage III colon cancer patients receive chemotherapy. Comorbidities are strong predictors of chemotherapy non-use, but the association differs by comorbid condition and is strongest with dementia. Given the survival disadvantage of colon cancer patients with comorbidities, further evidence on the risk–benefit ratio of chemotherapy according to the type and severity of comorbidity and on the extent to which the survival disadvantage of comorbidity is explained by less use or lower tolerability of chemotherapy is needed to foster personalized medical care in these patients.