Background: Many studies found better cancer survival in patients with a high socioeconomic status (SES) than in patients with a low SES. Comorbidity at the time of diagnosis may be more frequent in patients of lower SES, and negatively influences their survival. The authors studied the association between SES and serious comorbidity at the time of diagnosis among newly diagnosed cancer patients in The Netherlands.
Methods: Included in the analyses were patients registered in 1993 in the population-based Eindhoven Cancer Registry (southeastern Netherlands) with one of the most common carcinomas: breast (n = 457), lung (n = 442), colorectum (n = 384), prostate (n = 240), and stomach (n = 118). Information regarding comorbidity came from medical records. The SES of the patients was derived from their postal code of residence and stratified into three categories. The risk of being diagnosed with at least one other chronic condition was calculated using logistic regression analyses.
Results: The risk of being diagnosed with at least one other chronic condition was higher among patients with a low or intermediate SES than among those with a high SES for the five sites combined as well as for carcinomas of the breast or lung. The gradient was less clear for patients with colorectal carcinoma, whereas no socioeconomic variation in comorbidity was found for patients with carcinomas of the prostate or stomach.
Conclusions: Socioeconomic variation in the prevalence of serious comorbidity at the time of diagnosis does exist in some cancer sites, which may explain (partly) the socioeconomic gradient in survival observed in patients with tumors in these sites.