A new study carried out by researchers at Penn State College of Medicine has concluded a type of thyroid cancer caused by radiation exposure was more common among thyroid cancer patients who were near Three Mile Island during the partial meltdown in 1979.

Dr. David Goldenberg, who led the study, said the study used new tools which can detect genetic differences between normally-occurring thyroid cancer and the kind that's caused by radiation exposure.

Goldenberg in an interview Wednesday said he believes the findings contradict the government's long-held conclusion that radiation which escaped from the plant had

"It is our belief that the TMI event had a biological effect on thyroid cancers in this region," he said.

However, Goldenberg said the study doesn't prove whether or not there were more cases of thyroid cancer than would have occurred absent the accident.

He said more research is needed, and his team plans to expand the study by including cases of thyroid cancer cases among people living near TMI who were treated at other hospitals.

Also, Goldenberg said there's no evidence that the radiation-induced cases were more lethal than the others.

The study involved 44 people who were treated for thyroid cancer at Penn State Hershey Medical Center between 1974 and 2014. Twenty-nine of those, because their cancer arose at a time when they couldn't have been exposed to TMI-related radiation, were put in a control group. The fifteen whose cancer arose between 1984 and 1996 -- corresponding with the latency period for radiation-induced thyroid cancer -- were assigned to the at-risk group. The members of the at-risk group, the study concluded, were significantly less likely to have the form of cancer not associated with radiation, while the opposite was true of the control group.

The study was done using medical records and stored tumor samples from former thyroid cancer patients, and didn't directly involve the patients. Goldenberg said the researchers had no information about outcomes including whether the patients survived the cancer. However, he noted thyroid cancer is a highly-survivable disease.

He said the latency period for radiation induced thyroid cancer is between 7 and 20 years. However, people exposed at younger ages have a higher likelihood of eventually developing the cancer. Therefore, it's impossible to know whether or not additional cases caused by the 1979 exposure will arise, he said.

Goldenberg is a surgeon who cares for people with thyroid cancer. He said local residents who come down with disease often blame it on TMI, or wonder if TMI was the cause. He said some fellow researchers have told him it's no longer worth it to study possible connections between TMI and cancer, and the subject should be put to rest. However, Goldenberg said the research provides an opportunity to better understand the connection between radiation and thyroid cancer.

He said his research team went to great lengths to verify that the patients placed in the at-risk group were in fact in locations where they could have been exposed to radiation which escaped during the accident.

" It comes just as it seems TMI, built during the 1960s,