Large age and hospital-dependent variation in administration of adjuvant chemotherapy for stage III colon cancer in southern Netherlands

Background: The purpose was to assess factors associated with the administration of chemotherapy and their relation to survival at a population-based level. Methods: All patients diagnosed with primary colon cancer stage III from 2001 to 2007 in the area of the Eindhoven Cancer Registry were included (N = 1637). We examined determinants of the administration of adjuvant chemotherapy and their relation to survival. Results: The proportion of patients receiving adjuvant chemotherapy decreased with increasing age from 85% for patients <65 years to 68% for those 65-74 years and 17% for patients 75 years, with large interhospital variation. Elderly patients {odds ratio (OR) 0.1 [95% confidence interval (CI) 0.1-0.1]} and those with comorbidity [OR 0.6 (95% CI 0.5-0.8)] received adjuvant chemotherapy less often. Patients with an intermediate [OR 1.4 (95% CI 1.1-1.9)] or high socioeconomic status [OR 1.5 (95% CI 1.1-2.0)] or stage IIIC [OR 1.5 (95% CI 1.1-2.0)] received adjuvant chemotherapy more often. Adjuvant chemotherapy was the most important predictor of survival. In a multivariable analysis, older age was no longer a significant negative predictor of survival, in contrast to comorbidity, higher tumor stage, poor tumor grade, and male gender. The improvement in survival from 2001 to 2006 did not reach statistical significance. Conclusion: Adherence to guidelines for adjuvant chemotherapy was still suboptimal in 2007, especially for elderly patients, and differed widely between hospitals.