But Dr. Janet Butel of Baylor Medical College, who wrote the scientific article that prompted those headlines, came out Thursday to say they were not accurate.
"It's unnecessarily alarming, and I think that it's misinterpreting the data as is currently available," she said.
What Butel did find was that genetic material from a monkey virus called sv40 had been discovered in certain rare types of human cancer. That same virus had contaminated some batches of a polio vaccine given to between 10 and 30 million Americans before it was pulled from the market in 1961.
But she urged the public not to draw any conclusions that the vaccine was putting people at any greater risk of cancer.
"There is no data that provides a direct link between the virus that is being found in cancer today with anything related to the polio vaccine," Butel said.
She did suggest, however, that a ten-fold increase in a certain type of lung cancer called mesothelioma since 1960 was suspicious and warranted more study - especially since evidence of the monkey virus was found in some tumors. Other doctors say they'd look to other risk factors before sv40.
"We know that the mesotheliomas are associated with smoking and asbestos, things that happened during the war and right after the war associated with this very rare tumor," said Dr. Jeffrey Laurence of New York Presbyterian-Cornell Medical Center.
The National Cancer Institute has been tracking this for 40 years and says there's no definitive evidence that the monkey virus causes cancer, and that there's been no increase in cancer rates among people who received the polio vaccine.
But there's no doubt this new research will prompt new efforts to answer the question once and for all.
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