Too many small, inconsequential thyroid cancers are being treated, a team of doctors declared Wednesday as they accused the medical community of causing an "epidemic of overdiagnosis" for nearly four decades.
Many of the cancers that are being treated, according to medical investigators reporting in the journal Otolaryngology-Head and Neck Surgery, are abnormalities that are compatible with life.
The basic thesis -- overdiagnosis -- is a contrarian point of view and drew fire Wednesday from practicing physicians who say there is no way to reliably distinguish slow-growing, harmless cancers from those that are life-threatening.
"The bottom line is that thyroid cancer overall, in the majority of cases, it is not fatal," said Dr. Mark Marzouk, a thyroid cancer specialist and assistant professor of surgery at Stony Brook University Hospital.
"Now, having said that, it is also important to know that there are a few subtypes that are very aggressive in their behavior," added Marzouk, who was not involved the research.
The new medical investigation was conducted by doctors at both the Dartmouth Institute for Health Policy and Clinical Practice in New Hampshire and the Veterans Administration Medical Center in Vermont.
They established statistical evidence for decades of thyroid overdiagnosis in a study that examined overall incidence and gender differences in the disease between 1975 and 2009.
The majority of thyroid cancers in the United States are small, so-called papillary cancers, a common and less aggressive form of the disease.
The medical investigators found that since 1975, the incidence of thyroid cancer nearly tripled from 4.9 to 14.3 per 100,000 people, with virtually the entire increase due to the papillary form of the disease.
Subtracting other forms of thyroid cancer from papillary disease, researchers revealed that papillary malignancies escalated from 3.4 to 12.5 per 100,000 people during the same period.
They also found that thyroid cancers affect women more often than men. The number of cancers affected 6.5 women per 100,000 in 1975 but 14.9 per 100,000 34 years later, almost four times greater than the impact on men.
Incidence for men escalated from 3.1 per 100,000 to 6.9.
Despite rising incidence, the death rate has remained stable since 1975 at about 0.5 deaths per 100,000 people.
Dr. Doru Paul, an oncologist at Monter Cancer Center in Lake Success, said the study has merit but he doubts it will change the way he treats patients.
"If there was a real increase in cancer, there would be a real increase in mortality but the mortality is identical to what it was in 1975," Paul said.
Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in Manhattan, said there are reasons that more cancers are being found. "We have more sensitive tests and imaging, so yes we are going to find thyroid cancers."
Marzouk said the majority of thyroid cancers he treats are found incidentally, usually when people are seen for trauma caused in car accidents and their CT or MRI scans unexpectedly reveal malignancies.