While patients who had "low-risk" disease (stage 1) were less likely to receive radioactive iodine than patients with advanced thyroid cancer (stage 4), people with stage 2 and stage 3 cancers were just as likely as those with stage 4 tumors to receive the treatment.
The likelihood of receiving radioactive iodine also had a lot to do with where people were treated.
Overall, about 37 percent of women under age 45 with stage 1 tumors received radioactive iodine. But that ranged from 0 percent at some hospitals to more that 90 percent at others.
For a high-risk case -- a man over age 45 with stage 3 or 4 disease, the odds of getting radioactive iodine ranged from 25 percent at some hospitals to 90 percent at others. In this case, the guidelines would call for him to receive iodine treatment.
"The number of patients receiving radioactive iodine has increased significantly, and the researchers find that people with these earliest cancers are getting it with no apparent explanation as to why," said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. "There is a lot of variation in the use of radioactive iodine, which appears to be based more on preferences of the physician, patients or both, than any particular scientific or evidence-based reason."
Radioactive iodine treatment carries some risks, including a slight increase in the chances of getting leukemia or damage to nearby tissue such as salivary glands. Women have to avoid getting pregnant for six months to a year, and have to stay away from young children for about a week after treatment.
"The risk may be relatively minimal, but it's not without some risk," Lichtenfeld said.
But Dr. Edward Livingston, chairman of gastrointestinal and endocrine surgery at University of Texas Southwestern Medical Center, took the research to task, saying that the data doesn't support a conclusion tha
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