Abstract P2-10-09: Clinical correlations of serum vitamin D in patients undergoing neoadjuvant systemic therapy and survival outcomes for operable breast cancer

Abstract

Abstract Introduction: There has been increasing interest in the potential benefit of vitamin D to improve breast cancer outcomes. Pre-clinical studies suggest vitamin D enhances chemotherapy-induced cell death. We previously reported (Thomas A SABCS 2016) that low serum vitamin D levels were associated with not attaining a pathologic complete response (pCR) following breast cancer neoadjuvant chemotherapy (NAC). We report here the impact of vitamin D on survival parameters in an expanded cohort of patients. Methods: Patients from two Iowa registries who had serum vitamin D level measured before or during NAC were included. French patients enrolled in a previous study of the impact of NAC on vitamin D and bone metabolism were also eligible for this study. Vitamin D deficiency was defined as < 20 ng/mL. pCR was defined as no residual invasive disease in breast and lymph nodes. Survival was defined from the date of diagnosis to the date of relapse (PFS) or date of death (OS). Results: The study included 327 women. Median age was 51 years. Patients presented with HER2+, HR+/HER2- and triple negative (TN) tumors in 28.5%, 43.9% and 27.6% of the cases respectively. In this expanded cohort, vitamin D deficiency remained associated with the odds of not attaining pCR (OR 1.64; 95%CI: 1.02-2.66, p=0.04). Median follow-up was 5.33 years (range 0.5 to 9.8 years). Of these patients, there were 54 relapse and 52 deaths. In multivariate analysis, stage III disease, TN phenotype and the inability to achieve pCR were independently associated with a worse survival (Table 1). Table 1 PFS (Hazard Ratio, 95%CI)pOS (Hazard Ratio, 95%CI)pStage I - II1 1 III2.78 (1.56 – 4.95)0.0012.82 (1.57 - 5.05)0.001Tumor phenotype HR+/HER2-1 1 HER2+3.00 (1.28 – 7.06)0.0121.78 (0.76 – 4.08)0.174TN7.37 (3.26 – 16.69)< 0.0016.50 (3.07 – 13.76)< 0.001NAC response Non-pCR1 1 pCR0.19 (0.08 – 0.45)< 0.0010.22 (0.09 – 0.55)< 0.001Vitamin D < 20 ng/mL1 1 ≥ 20 ng/mL1.01 (0.57 – 1.78)0.971.03 (0.58 – 1.84)0.92 Vitamin D deficiency was not significantly associated with survival parameters in the general population; however a trend was seen in the TN population regarding the correlation with PFS (90 patients, 5-year PFS 60.4% vs. 72.3%, p=0.18). Conclusion: Vitamin D deficiency is associated with the inability to reach pCR in breast cancer undergoing NAC. A trend for worse survival was seen in the TN subgroup. The strong association between vitamin D deficiency and the inability to reach pCR warrant further evaluation in the TN subgroup. Prospective interventional studies are needed to elucidate if maintaining vitamin D levels during NAC, a highly modifiable variable, may be utilized to improve cancer outcomes, particularly in TN breast cancers. Citation Format: Viala M, Chiba A, Thezenas S, Delmond L, Lamy P-J, Mott SL, Schroeder MC, Thomas A, Jacot W. Clinical correlations of serum vitamin D in patients undergoing neoadjuvant systemic therapy and survival outcomes for operable breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-10-09.