Abstract P5-16-25: Serum 25-hydroxyvitamin D levels and oncologic outcomes of breast cancer patients receiving neoadjuvant chemotherapy

Abstract Background:According to prior studies, the role of serum vitamin D3 has been inconsistentand clinical implications of 25-hyrdoxyvitamin D (25-OHD) have been little studiedin breast cancer patients receiving neoadjuvant chemotherapy (NCT). Objectives: The aims of study were to investigate changes in 25-OHD levels before and after NCT and to determine the association of 25-OHD and oncologic outcomes including pathological complete response (pCR) in breast cancer patients. Patients and Materials: From January 2010 to December 2013, serum 25-OHD levels at pre- and post-NCT were measured in 377 breast cancer patients. The association of serum 25-OHD levels with clinicopathological data including breast cancer subtypes, pCR and survival were retrospectively analysed. Delta 25-OHD was calculated as serum 25-OHDlevels before minus after NCT. Results: Mean ageof study population was 48.7 yearsand mean follow-up periods were 35.9months.Mean baseline serum 25-OHD concentration was 14.60 ng/mL (standard deviation, 7.44) and more than 80% of patients showed insufficient 25-OHD levels. The mean 25-OHDat post-NCT was 12.16 ng/mL (standard deviation, 6.87).There was a significant decrease in serum 25-OHD after NACT (p<0.001).The pCR rates were 25.7% among study cohort.However, 25-OHD levels at baseline and post-NCT were not related to pCR and survival outcomes. No associations were found between pCR and delta 25-OHD. According to stratification by breast cancer subtypes, however, patients with ≥ -2.67 (median value) of delta 25-OHD revealed a trend of higher achievement of pCR and better survival in luminal A subtype. No associations were found among the other subtypes. Conclusions: Many Korean breast cancer patients showed insufficient serum 25-OHD levels at diagnosis of malignancy and a significant decrease in serum vitamin D3 after NACT was observed.No significant association of 25-OHD 3 with pCR and survival was found. Therefore, correction or maintenance of appropriate serum 25-OHD levels should be focused for bone health as comprehensive management of breast cancer during NCT.In addition, possible oncological aspects of 25-OHD should further researched individually considering breast subtypes. Citation Format: Park S, Lee JS, Kim JH, Lim SM, Park HS, Kim SI. Serum 25-hydroxyvitamin D levels and oncologic outcomes of breast cancer patients receiving neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-25.