TUESDAY, Nov. 22, 2005 (HealthDay News) -- Radiation therapy to treat cervical and rectal cancer in older women greatly increases the risk of pelvic fractures as these women go on with their lives, new research shows.
A lack of good treatment alternatives means doctors and patients need to be aware of these risks going forward, the researchers said.
"For some of these cancers, radiation really is the best way to treat them," said Dr. Nancy Baxter, lead author of the study and an assistant professor of surgery at the University of Minnesota Cancer Center in Minneapolis. "Radiation is proven effective. It's just what we do for survivors."
"In these three cancers, the benefit of radiation is so strong that I do not think [fracture risk] changes the risk/benefit ratio," added Dr. William Small, Jr., author of an accompanying editorial and a radiation oncologist with Northwestern Memorial Hospital in Chicago.
"Anybody who receives radiation should probably be followed for the rest of their lives or for a significant amount of time by a radiation oncologist," he said.
The study and editorial appear in the Nov. 23/30 issue of the Journal of the American Medical Association.
According to experts, the lifetime risk of a hip fracture for white women after 50 years of age is 17 percent, and a broken hip can change a woman's life irrevocably. About 50 percent of women who were able to walk before the fracture will no longer be able to do so independently, and about 50 percent of women who were living independently will now require assistance.
According to the study authors, the number of deaths attributable to hip fractures is comparable to the number of deaths due to pancreatic cancer and is only slightly lower than the number due to breast cancer.
Yet information on how many of these fractures might be due to pelvic irradiation has been anecdotal until now, Baxter said.
"Fractures are, unfortunately, common in older women. It's hard to hang your hat on it being radiation," she explained. "This study adds to the evidence that radiation does have a direct effect on bones, but it also gives us some kind of evidence as to how much it increases."
Baxter and her co-authors looked at cancer registry data on more than 6,400 women aged 65 and older who had been diagnosed with pelvic malignances (anal, cervical or rectal cancers) from 1986 through 1999. They then compared women who had undergone radiation therapy vs. those who had not.
Women who had undergone radiation therapy were more likely to have a pelvic fracture than women who did not. For anal cancer, 14 percent of women who had received radiation had a pelvic fracture over five years, compared to 7.5 percent of women who did not receive radiation. For cervical cancer, the numbers were 8.2 percent and 5.9 percent respectively, and for rectal cancer 11.2 percent vs. 8.7 percent.
Almost all of the fractures (90 percent) were hip fractures.
Women who had been treated for anal cancer were three times as likely to have a fracture compared with women who had not been treated with radiation. Women who had received radiation for cervical cancer or rectal cancer were about 65 percent more likely to have a fracture, the study found. The higher risk associated with anal cancer may reflect additional radiation to the femur (thigh bone) that often occurs in these cases, the researchers said.
Even a 65 percent increase could boost increased lifetime incidence of fractures from 17 percent to 27 percent, the authors pointed out.
The study looked only at older women, so the findings cannot necessarily be extrapolated to other populations such as men or younger women, Baxter said.
Newer radiation techniques may minimize the volume of normal tissue affected. But until these techniques are proven, women who have undergone radiation treatment need to be closely monitored.
"Everyone seeing older women who survived cancer and had pelvic radiation needs to be aware that they're at higher risk," Baxter said. "They need to have regular bone mineral density screenings, aggressive treatment for osteoporosis. Things that we know help with fractures are likely applicable. It's very important for primary care providers to be aware of the study."
More information
For more on radiation therapy for pelvic cancer, head to the University of Michigan.
