A drug commonly used to minimize the toxic effects of chemotherapy has been shown in mice to cause bone loss and promote tumor growth, according to the results of a recent study.

This drug, granulocyte colony-stimulating factor (G-CSF) -- also known as Neupogen, Neulasta, and Granocyte -- helps restore white blood cell counts that take a beating during chemotherapy, protecting cancer patients from an increased risk of infection.

According to researchers, G-CSF -- essentially a growth factor -- encourages bone breakdown. And any therapy that decreases bone density can enhance tumor growth in bones. So doctors are urged to closely monitor their patients during chemotherapy with regular bone density scans. They can also prescribe medications to prevent bone loss if necessary. And patients can protect their bones by consuming enough calcium and vitamin D and engaging in regular exercise.

Currently, research on cancer patients treated with G-CSF have not yielded the same strong results researchers found among mice.

The details of this study appear online in the journal Blood, and will be published in an upcoming print issue.