THURSDAY, April 28 (HealthDay News) -- Use of a costly breast cancer therapy called intensity-modulated radiation therapy is strongly influenced by what Medicare will pay for the treatment and where radiation oncologists practice, according to a new study.

Researchers analyzed Medicare data for 26,163 women with localized breast cancer who had surgery and radiation therapy between 2001 and 2005. During that time, Medicare billing for the treatment, called IMRT, increased more than 10-fold (from 0.9 percent to 11.2 percent of patients).

The average cost for radiation treatment within the first year after breast cancer diagnosis was $7,179 without IMRT and $15,230 with it.

Billing for IMRT was five times higher in regions of the country where the treatment was covered by local Medicare carriers than it was in areas where it was not covered, the researchers said. They also found that billing for IMRT was more common among patients treated in freestanding radiation treatment centers (7.6 percent) than among those treated in hospital-based outpatient clinics (5.4 percent).

The findings "suggest that with respect to breast radiation therapy, much of the variation in cost can be directly attributed to inconsistent treatment definitions and reimbursement rates authorized by Medicare and its intermediaries," concluded Dr. Benjamin D. Smith, of the M.D. Anderson Cancer Center in Houston, and his colleagues.

The study is published in the April 29 online edition of in the Journal of the National Cancer Institute.

The findings "confirm the suspicion of many, both within and outside of the health care industry, that medical decision making is too heavily influenced by reimbursement rather than medical necessity," Dr. Lisa A. Kachnic, of Boston University School of Medicine, and Dr. Simon N. Powell, of Memorial Sloan-Kettering Cancer Center in New York, wrote in an accompanying editorial.

More information

The American College of Radiology and the Radiological Society of North America have more about IMRT.