Serum selenium levels predict survival after breast cancer
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Studies have reported an inverse relationship between serum selenium levels and cancer incidence, but the impact of low serum selenium status on survival after a diagnosis of breast cancer has not been established.
We obtained a blood sample from 546 women diagnosed with a first primary invasive breast cancer between 2008 and 2015 in the region of Szczecin, Poland. Blood was collected after diagnosis, but prior to treatment. Serum selenium was quantified by mass spectroscopy and each patient was assigned to one of four categories (quartiles) based on the distribution in the entire cohort. Patients were followed from diagnosis to death over a mean follow-up of 3.8 years. Vital status was obtained by linkage to the Polish National Death Registry.
The 5-year overall actuarial survival was 68.1% for women in the lowest (< 64.4 µg/L) and 82.5% for those in the highest (> 81.0 µg/L) quartile of serum selenium. In an adjusted analysis, the hazard ratio for death was 2.49 (95%CI 1.53–4.04; P = 0.0002) for patients in the lowest quartile of serum selenium, compared to those in all other quartiles. The effect of low selenium on breast cancer-specific mortality was stronger for women who were past smokers (HR 6.03; 95%CI 1.96–18.6; P = 0.0002).
This study suggests that a selenium level in excess of 64.4 µg//L might be beneficial for women undergoing treatment for breast cancer and that selenium supplementation to achieve this level may favorably impact the outcome. Further studies are needed to confirm this association and to evaluate the impact of selenium supplementation on breast cancer survival among women with low post-diagnostic selenium levels.
KeywordsSelenium Breast cancer Mortality
We thank E Putresza and K Lachowska for technical support. J. Kotsopoulos is the recipient of a Cancer Care Ontario Research Chair in Population Studies and a Canadian Cancer Society Career Development Award in Prevention. S.A. Narod is the recipient of a Canada Research Chair tier I. The study was supported by grant of National Centre for Research and Development INNOMED/I/16/NCBR/2014.
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Conflict of interest
Jan Lubinski (first author) is CEO of Readgene which is a distributor of selenium supplements and offers measurement of selenium level. Authors TH, WM, and MM are employees of Readgene. JG, CC, AJ, TD, MF, JK, JK, PS, and SAN declare no conflict of interest.
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