Abstract P6-09-24: Vitamin D level impacts odds of pathologic complete response following neoadjuvant therapy in operable breast cancer

Abstract

Abstract Introduction: Pathologic complete response (pCR) following neoadjuvant systemic chemotherapy (NAC) serves as a measure of tumor responsiveness and is a recognized surrogate for improved long-term outcomes. Some, but not all, studies have found a positive association between vitamin D (VD) and disease-free survival. We investigated if VD at diagnosis or during chemotherapy impacts pCR following neoadjuvant chemotherapy for operable breast cancer. Methods: Patients from Iowa were eligible if they were enrolled in one of two Iowa registries and had serum from before or during NAC tested for VD. French patients enrolled in a previous study of the impact of NAC on vitamin D and bone metabolism were considered for this study. VD deficiency was defined as <20 ng/ml. pCR was defined as no residual invasive disease in breast and lymph nodes. Firth-penalized logistic regression multivariable model was used. Results: The final cohort included 144 women. 84.7% of VD levels were obtained before initiation of chemotherapy. There was no difference between the French and Iowa cohorts with regard to age (p=0.20), clinical stage (p=0.22), disease receptor status (HER2+ [Hormone receptor (HR)+ or HR-], HR+/HER2-, and Triple Negative) (p=0.32) and rate of pCR (p=0.34). French women had lower body mass index (mean 24.8 vs 28.8, p<0.01), lower VD levels (mean 21.5 vs 27.5, p<0.01) and underwent lumpectomy instead of mastectomy more frequently (75.3% vs 47.8%, p<0.01) than Iowa women. Only pCR differed between the VD sufficient and deficient groups (Table 1). In multivariate analysis, after adjusting for the effects of cohort, clinical stage, and disease type by receptor status, VD deficiency put a woman at 2.68 times increased odds of not attaining a pCR (95%CI: 1.12-6.41, p=0.03) (Table 2). This variable remained significant with VD deficiency defined as <30 ng/ml and when considering this variable continuously. Conclusion: In this retrospective cohort, VD level before or during NAC was associated with pCR. Prospective trials could elucidate if maintaining VD levels during NAC, a highly modifiable variable, can be utilized to improve cancer outcomes in addition to benefiting other established health outcomes. Table 1: VD Deficient and Sufficient Groups Vitamin D (ng/ml) Deficient (< 20)Sufficient (≥ 20)pN 5391 BMIUnderweight-Normal27 (50.9)47 (51.6)0.93 Overweight-Obese26 (49.1)44 (48.4) VD LevelBefore Chemotherapy45 (84.9)77 (84.6)0.96 During Chemotherapy8 (15.1)14 (15.4) GradeG1-224 (47.1)41 (46.1)0.91 G327 (52.9)48 (53.9) Clinical StageI-II37 (69.8)61 (67)0.73 III16 (30.2)30 (33) Receptor StatusHER2+ (HR+ or HR-)12 (22.6)29 (32.2)0.20 HR+/HER2-30 (56.6)37 (41.1) Triple Negative11 (20.8)24 (26.7) SurgeryBreast Conserving32 (60.4)58 (63.7)0.69 Mastectomy21 (39.6)33 (36.3) pCRNo43 (81.1)53 (58.2)<.01 Yes10 (18.9)38 (41.8) AgeMean (SD)48 (10.9)51 (10.3)0.15 Table 2: Odds of Not Attaining a pCR: Multivariable Results NOdds Ratio95% CIp-valueCohortIowa661.170.522.630.71 France77Ref Vitamin D (<20)Deficient532.681.126.410.03 Sufficient90Ref Clinical StageI-II97Ref III463.251.308.110.01Receptor StatusHER2+ (HR+ or HR-)411.060.402.810.91 HR+/HER2-675.502.0414.85<0.01 Triple Negative35Ref Citation Format: Thomas A, Thezenas S, Mott SL, Raman R, Viala M, Pouderoux S, Schroeder MC, Lamy P-J, Jacot W. Vitamin D level impacts odds of pathologic complete response following neoadjuvant therapy in operable breast cancer [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 P6-09-24.