Educational differences in cancer incidence, stage at time of diagnosis, and survival in Norway.

Abstract

Aim: The study investigates differences in cancer incidence, stage, and survival between municipalities with varying levels of education in Norway. It replicates the design of a similar study conducted in Oslo to assess whether similar patterns are present nationwide.

Method: We used aggregated data from the Cancer Registry of Norway (2014-2023) to calculate age-standardized incidence rates, stage at diagnosis, and five-year relative survival for colon, rectal, lung, melanoma, breast, and prostate cancer across municipalities. Municipalities were grouped by educational level (low, medium, high), and outcomes were compared.

Results: The study included 191,213 cases. Age-standardized incidence rates (per 100,000 person-years) differed significantly by education for all cancer types except breast cancer (p = 0.70). Melanoma and breast cancer incidence was highest in high-education areas (melanoma: 45.2 vs. 36.9; breast: 135.6 vs. 120.3), while lung cancer was highest in low-education areas (64.4 vs. 56.3). Colon, rectal, and prostate showed smaller but significant differences (colon: 54.7 vs. 54.5, p < 0.001; rectal: 24.5 vs. 25.9, p < 0.001; prostate: 189.8 vs. 191.5, p < 0.001). Low-education areas had the highest proportion of distant metastases for most cancers, with significant variation for lung (p = 0.003) and prostate (p < 0.001). Mid- or high-education areas more often had localized disease, except melanoma. Low-education areas had lower five-year relative survival, significant only for breast cancer (p = 0.037).

Conclusion: Cancer incidence, stage, and survival varied between municipalities grouped by inhabitants' educational level. Findings align with those of the Oslo study, highlighting consistent education-related disparities in cancer outcomes nationwide.