The potential of vitamin D for breast cancer treatment and prevention “has gained considerable international attention in recent years,” senior author Dr. Mark Clemons, from The Ottawa Hospital Cancer Centre, Canada, told Reuters Health.
“This study,” he added, “is novel in that we used higher doses of vitamin D in patients with stable bone metastases from breast cancer who were on a bone targeted therapy to see if vitamin D would either improve their pain or biochemical markers of bone turnover.”
As Dr. Clemons and his colleagues report in the November 13th online issue of Cancer, 40 patients with bisphosphonate-treated bone metastases were given 10,000 IU of vitamin D3 and 1000 mg of calcium each day for 4 months.
Markers of bone resorption did not change significantly during the study period. Moreover, although the number of pain sites dropped significantly, there was no significant change in the overall pain burden.
Vitamin D3 therapy was associated with a significant increase in serum calcium levels and with a significant drop in serum levels of parathyroid hormone. Treatment led to the identification of two patients with primary hyperparathyroidism, but no direct toxic effects were observed.
The discovery of these two cases is “important as these patients require different management,” Dr. Clemons noted.
“It is clear that vitamin D and calcium supplementation have an important role in general bone health. However their role in treating and preventing breast cancer remains unproven,” Dr. Clemons added. Moreover, “high doses of vitamin D can be toxic in certain patients.”