A strong skeleton is less likely to be penetrated by metastasizing
cancer cells, so dietary calcium might be the way to block
cancer's spread, according to researchers at the ANZAC Research
Institute in Concord, Australia. Using a mouse model of breast
cancer metastasis, the researchers found that a calcium deficiency
may increase the tendency of advanced breast cancer to target
bone. Dietary calcium, they reason, might help prevent the
spread of breast cancer to bone and serve as an adjuvant treatment
Their findings are presented in the Oct. 1 issue of Cancer
Research, a journal of the American Association for Cancer
According to the researchers, about 70 percent of patients
who develop advanced breast cancer will have secondary tumors
in the bone. The spread of cancer to bones leads to cellular
processes that physically break down existing bone, leading
to further pain and illness. In fact, the breakdown of bone
and subsequent bone re-growth forms what senior author Colin
R. Dunstan, Ph.D., terms a "vicious cycle" that turns bone
into an environment conducive to cancer growth.
To better understand the role of bone turnover in the spread
of cancer, Dunstan and his team compared the effects of a
low- and high-calcium diet in mice. They found that dietary
calcium deficiency - independent of the chemical factors that
control turnover - was related to a significantly higher increase
in cancer cell proliferation and the total proportion of bone
that had been penetrated.
"These results could have implications for patients with
breast cancer bone metastases or who are at high risk for
developing metastatic disease," Dunstan said. "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 Dunstan, his results call for further, directed
clinical trials "to investigate how calcium and vitamin D
status influence progression to metastatic disease, and to
determine if corrections of calcium and vitamin D deficiencies
are important in breast cancer patients."