Socioeconomic and geographic variation in adjuvant chemotherapy among elderly patients with stage III colon cancer in Norway - a national register-based cohort study.

Background: About half of the patients diagnosed with colon cancer are 70 years or older. Standard treatment for stage III colon cancer is major surgical resection followed by adjuvant chemotherapy (ACT). Norwegian guidelines recommend initiation of ACT within 6 weeks after resection.

Objective: This study investigated socioeconomic and geographic variation in the recommended provision of ACT to elderly patients with stage III colon cancer in Norway.

Methods: This population-based retrospective cohort study included patients aged 70 years or older diagnosed with stage III colon cancer between 2011 and 2021 who underwent major surgical resection. Individual data were obtained from national registries. Multilevel logistic regression analysis was used to model variation in provision of ACT.

Results: Of 4 501 included patients, 603 (13%) and 1 182 (26%) received ACT within 6 and 8 weeks after resection, respectively. The provision of ACT decreased with increasing age and frailty. Odds of ACT within 6 weeks decreased for patients with low socioeconomic status (SES) compared to high SES (odds ratio (OR) 0.67 (95% confidence interval (CI) 0.50-0.91)), and decreased for patients living alone compared to those living with a cohabitant (OR 0.72 (95% CI 0.58-0.91)). Geographic variation was found between hospital referral areas (OR 0.41-2.58).

Conclusions: Our study found that ACT provision to elderly stage III colon cancer patients is associated with SES and geography, indicating variation in guidelines adherence. Further research is needed to explore the impact of ACT timing among elderly patients with stage III colon cancer in Norway.