P5-05-01: Vitamin D Status in Newly Diagnosed Breast Cancer Patients Inversely Correlates with Tumor Size and Moderately Correlates with Outcome.

Abstract

Abstract Aims: To study the impact of Vitamin D (VitD) status and genetic variability in key VitD regulatory genes on patient and breast tumor characteristics, and on breast cancer related outcome. Methods: We examined serum 25-hydroxyvitamin D3 (25OHD) levels in a cohort of 1800 early breast cancer patients treated in Leuven between 2003 and 2010. Serum was collected at diagnosis for all patients; germline DNA from peripheral blood was also available for the majority of them. Serum 25OHD was measured by radioimmunoassay, and single nucleotide polymorphisms (SNP's) were assessed by Sequenom. Statistical analysis was done by multivariable regression models including age, BMI and season and by a Cox proportional hazard model for analysis of disease-specific survival and disease-free interval. Results: Lower 25OHD serum levels were significantly correlated with larger tumor size (0,4 ng/ml decrease in 25OHD per 1 cm increment in tumor size, p=0.0063) but not with lymph node invasion, estrogen receptor and HER2 status, or tumor grade. Serum 25ODH level was significantly affected by genotypes of rs10741657 and rs1993116 (25-hydroxylase; CYP2R1) and of rs222040, rs7041 and rs4588 (D-binding protein; DBP), yet its observed association with tumor size did not differ between distinct genotypes. Although not statistically significant, patients with higher 25OHD levels tended to have slightly improved survival. Also, a significant increase in relapse risk became apparent after 3 years for patients with 25OHD<30 ng/mL. Conclusion: Vitamin D Level in breast cancer patients inversely correlates with tumor size and moderately correlates with outcome. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-05-01.