Many women undergoing treatment for breast cancer are prescribed or recommended calcium and vitamin D supplements - which are suggested to help prevent and manage osteoporosis, an unwanted side effect of some breast cancer therapies.
However, new research published in Critical Reviews in Oncology/Hematology, has found that the recommended daily doses of these supplements may not prevent loss of bone mineral density (BMD) in these women.
Led by Dr Gary Schwartz from Wake Forest Baptist Medical Center, USA, the research team reviewed clinical trial data for the 'seemingly common sense prescribing practice' to see whether they offer real benefits.
"At the doses recommended, the data show that these supplements are inadequate to prevent loss of BMD," said Schwartz.
The team reviewed data from clinical trials that evaluated the effect of antiresorptive drugs on BMD and used the 'before-after' data from the comparison group to assess change in BMD in pre- and in post-menopausal women.
Overall, the results from 16 trials indicate that 500-1500 mg calcium and 200-1000 IU vitamin D, the doses commonly recommended, do not prevent loss of BMD in women with breast cancer.
Despite supplementation, women lost BMD in virtually every clinical trial reviewed, said the team.
"The take-home message is that this very common practice of supplementation doesn't really seem to be working," Schwartz said.
"Future trials are needed to evaluate the safety and efficacy of calcium and vitamin D supplementation in women undergoing breast cancer therapy."