Taking your calcium could stave off the spread of breast cancer to bones, a new study has found.

Researchers from the ANZAC Research Institute in Concord, Australia, found that being calcium deficient may increase the chance that a person's advanced breast cancer will spread to the bone.

The authors suggest that the use of bone-building drugs such as bisphsophonates or osteoprotegerin may suppress bone turnover and slow the progression of breast cancer in patients with the disease.
(CBC)

"These results could have implications for patients with breast cancer bone metastases or who are at high risk for developing metastatic disease," senior author Colin Dunstan said in a release.

"Many older women in our community are known to be calcium deficient due to low calcium dietary intake or due to vitamin D deficiency. These women could be at increased risk for the devastating effects of bone metastases."

According to the study, 70 per cent of patients with advanced breast cancer develop secondary tumours of the bone.

The findings are published in the Oct. 1 issue of Cancer Research, a journal of the American Association for Cancer Research.

High calcium inhibits tumour growth in mice

Researchers compared the effects of high- and low-calcium diets in mice that received injections of bone cancer cells. Some mice were concurrently treated with osteoprotegerin, a naturally occurring protein that regulates and protects bone mass.

Mice that were calcium deficient had a higher rate of cancer cell growth in their skeletons than mice with higher calcium levels.

Scientists found that those mice on the low-calcium diet had bone loss, a lower cortical bone area and larger tumours.  

Treatment with osteoprotegerin had the best outcomes, increasing bone volume and cortical bone area in mice on both low- and high-calcium diets. It also led to a higher rate of cancer cell death.

Researchers believe that the presence of high bone turnover in breast cancer patients could feed breast cancer tumour growth in bone.

As a result, patients with advanced breast cancer who have low calcium levels and high bone resorption rates (their bone breaks down quickly) "seem to be associated with rapid disease progression," reads the study.

"Treatment of breast cancer patients to decrease bone turnover through correction of calcium or Vitamin D deficiency may improve patient outcomes in the adjuvant as well as palliative settings," the report reads.

Though human trials are the next step, the authors suggest that the use of bone-building drugs such as bisphosphonates or osteoprotegerin may suppress bone turnover and slow the progression of breast cancer in patients with the disease.