Vitamin D (25-0H D3) status and pathological response to neoadjuvant chemotherapy in stage II/III breast cancer: Data from the NEOZOTAC trial (BOOG 10-01).

Background: Serum levels of 25-OH vitamin D3 (vitamin D) have been shown to be prognostic for disease-free survival in patients with breast cancer. We investigated the predictive value of these levels for pathological response after neoadjuvant chemotherapy in patients with breast cancer taking part in the NEOZOTAC phase-III trial. Additionally, the effect of chemotherapy on vitamin D levels was studied.

Materials And Methods: Serum vitamin D was measured at baseline and before the last cycle of chemotherapy. The relationship between these measurements and clinical outcome, as defined by pathological complete response in breast and lymph nodes (pCR) was examined.

Results: Baseline and end of treatment vitamin D data were available in 169 and 91 patients, respectively. Median baseline vitamin D values were 58.0 nmol/L. In patients treated with chemotherapy only, serum vitamin D levels decreased during neoadjuvant chemotherapy (median decrease of 16 nmol/L, P = 0.003). The prevalence of vitamin D levels < 50 nmol/L increased from 38.3% at baseline to 55.9% after chemotherapy. In the total population, baseline and end of therapy vitamin D levels were not related to pathological response. No associations were found between pCR and vitamin D level changes.

Conclusion: The significant decrease in vitamin D post-neoadjuvant chemotherapy suggests that vitamin D levels should be monitored and in case of decrease of vitamin D levels, correction may be beneficial for skeletal health and possibly breast cancer outcome.