CHICAGO (AP) - Radiation treatment for pelvic-area cancer can increase women's risks of breaking a hip later on, a study found.

The higher risks were seen in those with anal cancer, rectal cancer or cervical cancer, diseases that will be diagnosed in a total of nearly 30,000 U.S. women this year.

It is well known that radiation treatment can damage bone, but the fracture risks have not been well-studied, the researchers said. A broken hip can be devastating; for many elderly people especially, it can lead to deadly complications.

The study, published in Wednesday's Journal of the American Medical Association, involved 6,428 women who were 65 and older when diagnosed with pelvic cancer - women who already run a higher risk of broken bones because levels of bone-protecting estrogen plummet at menopause. About half the women received radiation for cancer.

Compared with the non-radiation group, anal-cancer radiation patients faced about triple the risk of developing pelvic fractures, mostly of the hip; while cervical and rectal cancer patients both faced about a 70 percent increased risk.

Dr. Nancy Baxter of the University of Minnesota Cancer Center, the study's lead author, said it is unclear whether the findings would apply to younger women or to men, whose bones tend to be denser than women's.

Doctors should offer women who have received radiation for pelvic-area cancer bone-density scans and treatment that might protect them from fractures - including calcium, medication and weight-bearing exercise, Baxter said.

Anal cancer patients faced the biggest risks because their tumors often spread to lymph nodes in the groin, where the hip bones are located, Baxter said. It is difficult to spare that part of the body from the radiation.

Baxter said the findings do not mean women with pelvic-area cancer should not be treated with radiation. "For some of these cancers, there's really no alternative," she said.

Radiation techniques have improved since the late 1980s and 1990s, when the study participants were treated, so the chances for damage may be lower for newly diagnosed patients, Baxter said.