Cancer Research Lab

Exogenous granulocyte colony-stimulating factor (G-CSF), often given during chemotherapy to promote neutrophil proliferation, decreases bone mineral density and causes the proliferation of bone tumors in mice, Washington University investigators report in a Blood First Edition paper pre-published online December 27.

Using murine osteoclastic tumor models, Dr. Katherine Weilbaecher and her colleagues in St. Louis, Missouri, administered G-CSF or saline daily for 8 days. On the fifth day of G-CSF treatment, the investigators injected tumor cells. Another group of animals received G-CSF after tumor cell injection.

Dr. Weilbaecher and colleagues report that “G-CSF administration increases osteoclast number and decreases trabecular bone area in vivo.” Bone tumor volume is also increased after G-CSF administration, but subcutaneous tumors are not increased.

The increase in bone tumor growth induced by G-CSF is independent of its effect on neutrophil proliferation, the investigators also report.

The magnitude of bone loss seen with the osteoclastogenesis induced by G-CSF “is similar to that which is seen in mouse models of oophorectomy,” Dr. Weilbaecher and colleagues comment.

The effect could be clinically significant, but Dr. Weilbaecher cautioned, in an interview with Reuters Health, that “our studies were conducted in mice and we do not yet know if they have any relevance for humans.”

“We do not think that these studies in mice should change the standard of care for patients with cancer” at this early stage of study, Dr. Weilbaecher continued. “However, our studies suggest that awareness of changes in bone health during cancer therapies could be important. Hopefully, clinical trials will be done to understand the effects of G-CSF in humans.”