( ays Weilbaecher an oncologist with the...)Researchers urge monitoring of bone health during chemotherapy

Although G-CSF had a strong effect on bone metastasis in the experimental mice, early clinical trials in humans using G-CSF with chemotherapy have so far shown no adverse effects on survival and no increase in bone metastasis. In fact, breast-cancer patients undergoing dose-dense chemotherapy with G-CSF support tend to have a longer disease-free period than those getting standard dosing without G-CSF.

"It's possible that women on G-CSF-supported chemotherapy could do even better if we paid more attention to skeletal health," says lead author Angela Hirbe, an M.D./Ph.D. student in Weilbaecher's lab. "Strengthening the skeleton would not only help prevent osteoporosis and fractures but also might give patients a survival advantage." In the laboratory mice studied, G-CSF increased the number and activity of bone cells called osteoclasts, which resorb bone material as part of the normal process of bone turnover. The resulting loss of bone density created a favorable environment for bone tumor growth.

When the researchers injected melanoma or breast cancer cells into mice, those getting G-CSF developed a two-fold increase in tumor burden, a measure of the size and severity of tumors, compared to those that did not receive G-CSF. Interestingly, mice treated with a bisphosphonate, an anti-osteoporosis agent that inhibits osteoclasts, were resistant to the effects of G-CSF on bone tumor growth. Weilbaecher is currently investigating bisphosphonates as a means to prevent tumor metastasis to bone in breast cancer patients.

"We used G-CSF as a tool to understand the implications for tumor growth when osteoclast activity is revved up," Weilbaecher says. "But G-CSF isn't unique in its effect. For example, antihormone therapies used to tre
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Source:Washington University School of Medicine