Mixed reviews for growth factors.

In addition to malignant cells, many cancer-killing drugs also destroy some normal cells -- in particular, those in the bone marrow that develop into blood cells. Scientists are assessing how to use growth factors to help the body recover from these and other damaging effects of chemotherapy, but a new analysis suggests the compounds may not be worth the cost.

Researchers at Indiana University Medical Center in Indianapolis reviewed results from two studies, one conducted by them, the other conducted at Duke University Medical Center in Durham, N.C. Both studies focused on the effects of a bone marrow growth factor administered to people with small-cell lung cancer. The growth factor increased treatment costs -- in some cases more than sixfold -- but did not improve the overall survival rate of those in the study, says Indiana's Edward P. Fox.

Other studies by the two research groups have now determined safe doses of a newer growth-factor product, human stem cell factor, which is produced by genetically engineered bacteria. When given to women undergoing drug therapy for breast cancer, this growth factor led to modest increases in infection-fighting blood cells and in other types of blood cells, but it also stimulated allergic reactions, report Michael S. Gordon and his colleagues at Indiana University. Jeffrey Crawford and his co-workers at Duke observed similar changes when they gave the compound to patients undergoing therapy for non-small-cell lung cancer.

Another growth factor, called PIXY321, is two molecules in one. It contains granulocyte-macrophage colony stimulating factor linked with interleukin 3. In patients who have undergone an autologous bone marrow transplant, this "fusion" molecule speeds the replacement of red blood cells by about two weeks and of platelets by three days, compared to those receiving no growth factor or treated with the granulocyte-macrophage colony stimulating factor alone, reports Julie M. Vose of the University of Nebraska Medical Center in Omaha.