Pelvic Radiotherapy Increases Risk of Bone Fracture

NEW YORK NOV 22, 2005(Reuters Health) - Older women who undergo pelvic radiation to treat cervical, anal or rectal cancer have an increased risk of pelvic fracture, new study results indicate. "Potentially, these women could be targeted for preventive strategies," such as bone mineral density screening, drug therapy to prevent osteoporosis and fall prevention, the researchers suggest.

Although it is known that therapeutic radiation can damage bone, the authors of the report point out that the specific risk associated with standard-course radiation treatment is not clear.  Because pelvic fractures, including hip fractures, are a major cause of illness and death in older women, an estimation of the risk would indicate if interventions to prevent fractures are warranted for these patients.

To assess the risk, a team led by Dr. Nancy N. Baxter from the University of Minnesota in Minneapolis linked data from the Surveillance, Epidemiology, and End Results cancer registry to Medicare claims data.  They report their findings in the Journal of the American Medical Association.

The study included 6,428 women ages 65 or older who between 1986 and 1999 were treated for pelvic malignancies.  Of these women, 2,855 underwent radiation therapy.

Within the first five years of the study, radiation therapy for anal cancer was associated with the highest rate of pelvic fractures: 14.0 percent in the radiation group versus 7.5 percent in those who did not undergo radiation.  Similar patterns were observed among women with cervical cancer (8.2 percent versus 5.9 percent) and those with rectal cancer (11.2 percent versus 8.7 percent).

Baxter"s group attributes the higher risk among patients with anal cancer to the need to often treat cancerous lymph nodes in the groin area, which are difficult to treat without also exposing the thighbone to radiation.

Even for the other two cancers, the increased risks are "substantial and clinically significant," the investigators note.

In a related editorial, Dr. William Small, Jr., from Northwestern University in Chicago, and Dr. Lisa Kachnic, from Boston University Medical Center, point out that this potential side effect "should be discussed with the patient at the time of radiation oncology consultation."

They also offer the hope that better targeting of radiation therapy currently under study may reduce the volume of normal tissue that is exposed to radiation, thus decreasing the adverse side effects.

SOURCE:

• Journal of the American Medical Association, November 23/30, 2005.