NEW YORK (Reuters Health) – Men who receive radiation treatment for prostate cancer are at greater risk of hip fracture, a new study in the March 16 issue of Cancer reports.

Based on the findings, men with prostate cancer considering their treatment options should be told about the risk associated with radiotherapy, especially if they already have other risk factors for hip fracture, Dr. Sean P. Elliott of the University of Minnesota in Minneapolis, the study’s first author, told Reuters Health. Right now, he added, “it’s not on the radar of common complications we discuss.”

Women are known to be more prone to hip fracture after pelvic external beam radiotherapy (EBRT) for gynecological or anorectal malignancy, Dr. Elliott and his colleagues note in their report. But it’s unclear whether EBRT to the pelvic area increases hip fracture risk in men as well.

To investigate, the researchers looked at data from the Surveillance, Epidemiology and End Results (SEER) database on 45,662 men 66 and older who had been diagnosed with prostate cancer between 1992 and 2004.

After adjustment for covariates, the primary outcome of hip fracture was 76% more common among the men who received EBRT, although the secondary outcome of distal forearm fracture was not.

Men who had both radiation and androgen suppression therapy were 2.45 times more likely to sustain a hip fracture than the men who had radical prostatectomy, and at 1.4 times greater risk of hip fracture than those who had EBRT only. The likelihood of distal forearm fracture was 43% higher in men given radiation and hormone suppression therapy compared to those who underwent radical prostatectomy only.

Given that increased fracture risk associated with radiation didn’t extend to the forearm, the effect seems to be radiation-specific, the researchers say. “There’s very good laboratory basic science evidence that radiation therapy induces bone loss through death of the bone forming cells, the osteoblasts,” Dr. Elliott said.

According to the researchers, 51 men would need to be treated with EBRT in order to produce one hip fracture in a 10-year period. “Given that more than 28% of the nearly 200,000 men diagnosed with prostate cancer each year receive EBRT, 3-D conformal EBRT may be linked to approximately 1,000 hip fractures each year,” they write.

Older men, who are already at increased hip fracture risk, are more likely to be treated with radiation than younger men, Dr. Elliott pointed out. Forty-four percent of men in the current study received EBRT. “Here you have an elderly patient population who generally are in suboptimal health who are already at higher risk of fractures,” he added. “I think this points to an important public health concern.”

It’s possible that intensity modulated radiation therapy (IMRT), a newer more specific treatment than EBRT, could be less harmful to bones, Dr. Elliott suggested. However, he added, IMRT typically exposes patients to a higher overall dose of radiation, on the order of 80 gray, compared to the lower 70s for EBRT. The current study couldn’t examine the risks associated with IMRT, which came into widespread use in 2003.

While it’s not clear how the increased fracture risk associated with radiation might be reduced, Dr. Elliott said, it’s likely worthwhile to counsel prostate cancer patients who receive the treatment about inexpensive bone-preserving measures such as weight loss, exercise, quitting smoking, and taking calcium supplements and vitamin D.

“There’s also the option of more expensive methods like bisphosphonates,” he added, “although how that would interact with the cell death caused by radiation is unclear.”

Cancer