Stem cell transplant boosts breast cancer risk

NEW YORK (Reuters Health) - Female cancer survivors who have been treated with a type of stem cell therapy called hematopoietic cell transplantation, or HCT, have an increased long-term risk of developing breast cancer, according to US and European researchers.

Lead investigator Dr. Debra L. Friedman told Reuters Health that HCT is being used with "greater success to treat a number of malignancies as well as non-malignant conditions. It is essential for long-term survivors and their health care providers to understand the potential adverse long-term outcomes associated with this therapy."

Among a group of 3,337 women who had HCT and survived for at least 5 years, Friedman, of the Fred Hutchinson Cancer Research Center, Seattle, and colleagues found that 52 developed breast cancer after a median of 12.5 years.

The 25-year cumulative incidence of breast cancer was 11 percent. The incidence of breast cancer was significantly higher in survivors who received total body irradiation (17 percent) than in those who did not (3 percent).

The longer since HCT, the greater the breast cancer risk.

Results also showed the use of total body irradiation prompted a fourfold greater risk of breast cancer and being 18 years old or younger at the time of HCT carried a hazard ratio of 9.5.

Breast cancer after HCT is a potential adverse outcome, noted Friedman, "and thus it is important for women at risk to undergo regular screening...to facilitate early detection."

"More research," she concluded, "is required to better understand other risk factors for breast cancer in these survivors."

SOURCE: Blood, January 15, 2008.