Immunity Boosters May Raise Leukemia Risk

There may be a small leukemia risk from drugs used to boost immunity during cancer chemotherapy, a new study suggests.

Cancer chemotherapy often decreases the number of the body's infection-fighting white blood cells. Drugs known as growth factors boost the growth of new white blood cells during chemo.

But the drugs, G-CSF (such as Neupogen) and GM-CSF (such as Leukine), may themselves cause rare cases of leukemia, find Columbia University researcher Dawn Hershman, MD, and colleagues.

Hershman's team looked at data collected on more than 5,500 women—aged 65 and older—treated with chemotherapy for breast cancer.

Chemotherapy itself can cause leukemia. Indeed, 1.04 percent of the women who did not receive growth factors developed leukemia. But 1.77 percent of the women treated with G-CSF or GM-CSF developed leukemia. Statistically, the drugs seemed to double a woman's leukemia risk—although that risk remained quite small.

"The benefits of G-CSF may still outweigh the risks," Hershman and colleagues conclude. "However, G-CSF use should not be assumed to be risk free."

The study appears in the Feb. 7 issue of the Journal of the National Cancer Institute. An editorial by Ivo P. Touw, PhD, and Marijke Bontenbal of Erasmus University in Rotterdam, Netherlands, accompanies the study.

Touw and Bontenbal note that even if growth factors are linked to leukemia, the drugs' risks are much smaller than their benefits for cancer chemotherapy patients.

SOURCES: Hershman, D. Journal of the National Cancer Institute, Feb. 7, 2007; vol 99: pp 196-205. Touw, I.P. and Bontenbal, M. Journal of the National Cancer Institute, Feb. 7, 2007; vol 99: pp 183-186.