Income, treatment patterns and outcome in patients with stage IV colorectal cancer.

[INTRODUCTION] This study explores the association between income and patient- and treatment characteristics, diagnosis through screening and survival of patients with synchronous metastasized CRC.

[METHODS] Patients diagnosed with stage IV CRC between 2015 and 2023 were selected from the Netherlands Cancer Registry. Income at postal code level was used (Statistics Netherlands). Multivariable logistic regression analyses were used to determine the association between income and treatment. Crude relative survival stratified for income was calculated, as well as relative excess risks of death using a multivariable generalized linear model.

[RESULTS] The study included 24,666 patients, with respectively 33%, 35% and 32% having higher, intermediate and lower income. Detection through screening was more often realized in the higher income group compared to intermediate and lower income (9% vs. 8% vs.6%, p < 0.001). Among patients with single-organ metastases, higher income patients were more often treated with curative intent for metastases to the liver (40% vs. 35% vs. 29%, p < 0.001) and peritoneum (36% vs. 29% vs.22%, p < 0.001) compared to intermediate or lower income, also in multivariable analyses. Similarly, systemic therapy was given more frequently to patients with higher income than those with intermediate or lower income (56% vs. 51% vs.42%, p < 0.001). Crude 3-year relative survival was 21% (lower), 22% (intermediate) and 26% (higher income, adjusted RER higher vs. lower income: 0.93, [95%CI 0.90-0.97]; intermediate vs. lower income: 0.95, [95%CI 0.92-0.99]).

[CONCLUSIONS] Patients with higher income were more likely to receive tumour directed treatment, including curative intent treatment which may result in the observed longer survival.