Plasma protein LEG1 homolog and post-menopausal breast cancer risk in the UK Biobank

Abstract We previously identified and confirmed a positive association between plasma protein LEG1 homolog and incident post-menopausal breast cancer risk in two prospective cohort studies that measured the protein using the SomaScan platform. To further confirm this finding in a cohort that used a different proteomics platform, Olink, we investigated this association in the UK Biobank. Among 9,537 post-menopausal, White women followed for a median of 11 years and with protein data, 295 breast cancer cases were identified. Adjusting for breast cancer risk factors, per doubling, the hazard ratio was 1.14 (95% confidence interval CI 0.96-1.35). While the direction of association was consistent, the magnitude was not as strong as in our prior two cohorts (HR per doubling: 1.45, 1.24) and not statistically significant. Data from the UK Biobank provide modest support for plasma protein LEG1 homolog as a risk factor for post-menopausal breast cancer. A quantitative targeted assay is needed.