Vitamin D deficiency and early breast cancer: an Australian experience.

Abstract

AIM: Adequate levels of vitamin D are important for optimal bone health. Australian women with early breast cancer are frequently vitamin D deficient and are exposed to additional risk factors for osteoporosis. To gauge the burden of vitamin D deficiency, this study was designed to assess serum 25(OH)-D levels at two time-points: at commencement and completion of adjuvant systemic chemotherapy. METHODS: Serum 25(OH)-D levels were measured in patients over two time periods: 2009–2011 (cohort 1) and 2012–2016 (cohort 2). Cohort 1 included 253 women and assessed 25(OH)-D levels at chemotherapy completion. Changes in serum 25(OH)-D levels were followed in a subgroup of patients (n = 63, subgroup A) at 3 and at 12 months. Cohort 2 included 267 patients and assessed 25(OH)-D levels during chemotherapy. Baseline 25(OH)-D levels were measured within weeks of surgery, and a subgroup (n = 102, subgroup B) agreed to check levels at chemotherapy completion and 3 months later. RESULTS: In cohort 1, 53% (of 253 women) were vitamin D deficient (< 50 nmol/L) after systemic chemotherapy and in cohort 2, 44% (of 267) had deficient serum 25OH-D levels prior to chemotherapy. In the majority, the deficiency was mild. In subgroup A, there was a considerable improvement in serum 25(OH)-D levels, from 63% deficient. In subgroup B, all 102 women had normal vitamin D levels prior to chemotherapy (>50 nmol/L). After chemotherapy, 51% had become deficient, but following replacement, only 6% were deficient 3 months later. CONCLUSION: Vitamin D deficiency is common in Australian women with early breast cancer. Assessment and replacement of vitamin D should become part of routine management in this population.