Document Type : Research Articles
Breast Division, Department of Surgery, National Cancer Institute, Bangkok, Thailand.
Department of Research, National Cancer Institute, Bangkok, Thailand.
Department of Pathological, National Cancer Institute, Bangkok, Thailand.
Background: Low 25-hydroxyvitamin D [25(OH)D] levels in serum are associated with breast cancer risk. This
study was conducted to determine the impact of 25(OH)D deficiency on survival of breast cancer patients. Methods:
In a retrospective cohort study of 303 patients diagnosed with breast cancer during 2011-2012 at the National Cancer
Institute Thailand, all cases were followed up for 7 years. The 25(OH)D was measured by high-performance liquid
chromatography (HPLC). Clinical and pathological data were collected. The Chi-square test, Kaplan-Meier and Cox
regression model were used to assess the association between 25(OH)D levels and risk of death. Results: Of the 303
cases aged between 24 and 78 years 51 (16.8%) died during follow-up from any cause. The mean 25(OH)D levels was
25.1±7.54 ng/ml (8.2 – 61.0 ng/ml). Thirty-three patients (10.9%) were stratified as inadequate or deficient group (<16
ng/ml) with mean survival time of 60.65 months compared to 76.24 months in insufficient or sufficient group (≥16 ng/
ml). Multivariate analysis adjusted for age, body mass index, stage, lymph node metastases, and immunohistochemical
(IHC) findings (ER, PgR, HER-2, Ki-67 and P53) showed that patients with low 25(OH)D levels (<16 ng/ml) at diagnosis
had a significantly higher risk of death (hazard ratio = 2.5-2.9) than the group with high 25(OH)D levels (≥16 ng/
ml). Conclusion: A concentration of 25(OH)D below 16 ng/ml was found to be independently associated with poor
survival in breast cancer patients, regardless of age, lymph node status, stage or breast cancer subtype. An investigation
of potential benefit of 25(OH)D supplements appears warranted.