Abstract 3285: Predictors of plasma 25-hydroxyvitamin D concentrations among breast cancer survivors
Authors: Shin Woo-kyoung , Kim Zisun , Youn Hyun Jo , Cho Jihyoung , Lee Jung Eun 
Published: July 2017

Abstract
Background: A review of recent evidences suggests that circulating 25-hydroxyvitamin D (25-OHD) concentrations are associated with better prognosis among breast cancer survivors. However, little is known about modifiable factors for vitamin D status among breast cancer survivors. We aimed to explore demographic, lifestyle, and clinical factors associated with vitamin D status among breast cancer survivors.
Methods: We included a total of 207 breast cancer survivors aged 21-79 years who were enrolled between 2015 and 2016 at three large hospitals. Participants had been diagnosed with stage I to III primary breast cancer and had breast cancer surgery at least 6 months before enrollment. We asked participants about demographic, socioeconomic, and lifestyle factors. Clinical data were extracted from medical records. Dietary intake was assessed using 3-day dietary records. Plasma 25-OHD concentrations were measured by the electrochemiluminescence immunoassay. We fit a multivariable linear regression model to predict plasma plasma 25(OH)D with all candidate predictors with p ≤ 0.1 in the univariate analysis.
Result: Mean value (SD) of plasma 25(OH)D concentrations were 23.75± 12.15ng/ml among users of supplement containing vitamin D, and 13.35± 8.62ng/ml among non-user. In the univariate linear regression models, we identified the following independent predictors associated with plasma 25-OHD concentrations: vitamin D intake from supplement, calcium intake from supplement, vitamin D from food, use of any supplement, body mass index (BMI), months after diagnosis, season of blood draw, daily sun exposure during the last 2 years, smoking habit, skin change after sunburn, suncap use, parity, and ER status. When we included all of these predictors in the multivariate linear regression models, we found that use of any supplement (β = 1.19 for use vs. nonuse, p&lt;0.001), BMI at diagnosis (β = -0.08 for 1 kg/m2 increment, p=0.02), season of blood draw (β = 0.83 summer vs. spring, p=0.008; and β = 0.75 fall vs. spring, p=0.01), and daily sun exposure during the last 2 years (β = - 0.0005 for 1 minute increment, p=0.02). Predicted models explained 23.95% of the total variability in plasma 25-OHD concentrations.
Conclusions: We found that supplemental use, BMI at diagnosis, season of blood draw, and daily sun exposure during the last 2 years were associated with plasma 25-OHD concentrations among Korean breast cancer survivors. Future studies are needed to investigate the role of vitamin D in the progression of breast cancer among Korean breast cancer survivors. Funding information: This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2014R1A2A2A01007794).
Citation Format: Woo-kyoung Shin, Zisun Kim, Hyun Jo Youn, Jihyoung Cho, Jung Eun Lee. Predictors of plasma 25-hydroxyvitamin D concentrations among breast cancer survivors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3285. doi:10.1158/1538-7445.AM2017-3285