CHICAGO, Illinois (Reuters) -- Radioactive "seeds" used to treat prostate cancer in men pose no radiation risk to their wives or families, who would absorb more radiation simply living in the high-altitude city of Denver, researchers said Monday.
"We can now tell a woman, 'The amount of radiation you will get from your husband in one year is less than you would get from living in Denver for three or four months,"' said Jeff Michael, a radiation oncologist at Washington University School of Medicine in St. Louis, Missouri.
Researchers affixed badges that measure radiation exposure on the skin of the wives, children and even pet dogs of 40 men who underwent prostate cancer treatment with the seeds -- radioactive material encased in a metal tube smaller than a rice grain.
At most, spouses received radiation of 14 millieme, compared to the 50 to 85 millieme absorbed by a Denver native or the 20 millieme received on a round-trip flight between New York and Tokyo, according to the study presented at the annual meeting of the Radiological Society of North America.
People living at high altitudes or traveling in planes absorb more radiation because there is less of the protective atmosphere to shield them from solar radiation.
The average person is exposed to between 200 and 400 millieme a year, and experts say annual exposure from nonmedical or occupational sources should be limited to not more than 500 millieme.
In the treatment, called radiotherapy, about 100 of the radioactive seeds are implanted to bombard the cancerous cells.
One in four men whose diagnosis shows his prostate cancer has not spread opts for this style of treatment, which studies have shown has a 78 percent success rate after 10 years.
This year, about 180,000 U.S. men will be diagnosed with prostate cancer, the second-leading cause of cancer death in U.S. men after lung cancer. But in 80 percent of cases the disease is diagnosed before it has spread beyond the prostate.