A new study suggests that older women who receive pelvic radiation treatment for cervical, anal or rectal cancer may have an increased risk of pelvic fracture.
The results of the study indicate that these women should probably be targeted for preventive strategies such as bone mineral density screening and drug therapy in order to prevent falls and osteoporosis.
The authors of the report say that although it is known that therapeutic radiation can damage bones, the specific risk associated with standard-course radiation treatment is unclear.
Pelvic fractures, including hip fractures, are a major cause of illness and death in older women, and an estimation of the risk would therefore indicate whether interventions to prevent fractures are helpful for such patients.
In order 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.
Their study included 6,428 women ages 65 or older who between 1986 and 1999 were treated for pelvic malignancies; of these 2,855 underwent radiation therapy.
It appears that 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.
The team believes the higher risk among patients with anal cancer can be attributed to the necessity to often treat cancerous lymph nodes in the groin area, which are difficult to treat without also exposing the thighbone to radiation.
But the researchers say that even for the other two cancers, the increased risks are substantial and clinically significant.
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.
Experts are optimistic that the improved 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.
The findings are published in the Journal of the American Medical Association.