Gross CP et al. (2007) The impact of chronic illnesses on the use and effectiveness of adjuvant chemotherapy for colon cancer. Cancer 109: 2410–2419

Adjuvant chemotherapy for colon cancer reduces mortality in patients of all ages; however, several studies have reported an inverse correlation between age and receipt of adjuvant therapy. The increased burden of chronic disease in elderly patients with cancer might explain the lower use of adjuvant therapy in this population. To determine the effect of comorbid conditions on the use and effectiveness of adjuvant chemotherapy in colon cancer, Gross et al. conducted a cohort study comprising 5,330 patients (median age 76 years) with stage III disease.

Overall, approximately 44.7% of the study population had 1 or 2 comorbid conditions and 8.8% had 3 or more. The probability of receiving chemotherapy was inversely correlated with age and number of comorbid conditions. Patients with heart failure were significantly less likely to receive chemotherapy than were patients without this condition (adjusted odds ratio [OR] 0.49, 95% CI 0.40–0.60; P <0.001). The probability of receiving adjuvant therapy was also reduced in patients with chronic pulmonary disease (OR 0.83, 95% CI 0.70–0.99; P = 0.04) or diabetes (OR 0.81 95% CI 0.68–0.97; P = 0.02). Patients who received adjuvant therapy had higher rates of 5-year overall survival than did untreated patients, and this relationship held true when patients were stratified according to comorbid condition. The risks of all-cause, condition-specific or toxicity-related hospitalization were not influenced by the presence of heart failure, chronic obstructive pulmonary disease or diabetes. The authors suggest that further study to explore the effectiveness of adjuvant therapy in the presence of comorbidity is greatly needed.