a register-based cohort study among Danish females
Background: The purpose of this study was to investigate whether there is an association between stage of incident breast cancer (BC) and personal income three years after diagnosis. The analysis further considered whether the association differed among educational groups. Methods: The study was based on information from Danish nationwide registers. A total of 7,372 women aged 30¿60 years diagnosed with BC, 48% with metastasis, were compared to 213,276 controls. Generalised linear models were used to estimate the effect of a cancer diagnosis on personal gross income three years after diagnosis, stratified by education and stage of cancer. The models were adjusted for income two years prior to cancer diagnosis and demographic, geographic and co-morbidity covariates. Results: Adjusting for income two years prior to cancer diagnosis and other baseline covariates (see above), cancer had a minor effect on personal income three years after diagnosis. The effect of metastatic BC was a statistically significant reduction in income three years after diagnosis of ¿3.4% (95% CI ¿4.8;-2.0), ¿2.8% (95% CI ¿4.3;-1.3) and ¿4.1 (95% CI ¿5.9;-2.3) among further, vocational and low educated women, respectively. The corresponding estimates for the effect of localised BC were ¿2.5% (95% CI ¿3.8; ¿1.2), ¿1.6% (95% CI ¿3.0; ¿0.2) and ¿1.7% (95% CI ¿3.7; 0.3); the latter estimate (for the low-educated) was not statistically different from zero. We found no statistically significant educational gradient in the effect of cancer stage on income. Conclusions: In a Danish context, the very small negative effect of BC on personal income may be explained by different types of compensation in low- and high-income groups. The public income transfers are equal for all income groups and cover a relatively high compensation among low-income groups. However, high-income groups additionally receive pay-outs from private pension and insurance schemes, which typically provide higher coverage for high-income workers.