PITTSBURGH — People diagnosed with a particular type of thyroid cancer and aggressively treated for it actually didn’t have cancer after all.

That’s the conclusion of 24 endocrinology pathologists from seven countries, which the University of Pittsburgh School of Medicine empaneled to reconsider the diagnosis and treatment of Encapsulated Follicular Variant of Papillary Thyroid Carcinoma.

The panel reviewed numerous tumor-cell samples and did an exhaustive review of the medical literature, among other efforts, before concluding that the condition was precancerous but not cancer itself.

The panel determined that the precancerous nodule that causes a lump in the neck rarely recurs or leads to complications once removed, with no further treatment necessary.

“We’ve known for a significant amount of time that this type of cancer is very indolent (inactive) with low potential to spread to the neck or outside of it, or to recur, or to cause death,” said Yuri E. Nikiforov, a professor of pathology and director of Pitt’s Division of Molecular and Genomic Pathology. “Still we had to call it a cancer.”

That’s because the nuclei of cells in the nodule look like that of cancer cell under the microscope, he said. But considering it a cancer represents an overdiagnosis resulting in overtreatment, including removal of the entire thyroid, radioactive iodine treatment and annual re-examinations.

Nikiforov led the effort to organize the panel and then served as lead author of the study published online Wednesday in JAMA Oncology.

The panel of experts said these specific thyroid nodules that cause a lump in the neck must be removed but additional treatment is unnecessary with less than a 1 percent chance of recurrence and low potential for complications.

“For that reason, we concluded we shouldn’t call it a cancer and shouldn’t subject patients to the psychological stress of that name, along with a second surgery to remove the rest of the thyroid, radioactive iodine treatment, with follow-up examinations, and bloodwork every year for the rest of their lives,” Nikiforov said. “The risk of being harmed by this disease is extremely low.”

To his knowledge, he said, the study represents the first time in the modern era of medicine that a type of cancer has been reclassified as a noncancerous: “I hope it will set an example for other expert groups to address nomenclature of various cancer types that have indolent behavior, to prevent inappropriate and costly treatment.”

Certain types of prostate, breast and lung cancers, he said, also are indolent forms that could be reclassified by following the blueprint the thyroid panel established in the JAMA study, he said.

In the United States, 65,000 people are diagnosed annually with thyroid cancers including 12,000 people diagnosed with the encapsulated-follicular-variant cancer. It can occur at any age but most commonly is found in middle-aged females with a female-to-male ratio of 5-1.

The study provides physicians sufficient basis to refrain from treating the condition as a cancer, he said: “Patients who have such a diagnosis should contact their doctor with the request to have their diagnosis reviewed and reclassified, according to what the study recommends.”

He also said the panel will present its results to the World Health Organization in two weeks to have the condition reclassified. “When you publish such a consensus paper, a doctor has the right to rediagnose it,” he said. “I have cases on my desk today and tomorrow I will start calling them as the new entity, and the word cancer will no longer be given to these patients.”

Gene Finley, deputy director of medical oncology for the Allegheny Health Network, said the well-designed study involving many experts in the field supports a trend in thyroid-cancer treatment in backing away from aggressive treatment.

“You don’t need to do much to manage people with thyroid cancers, and you need to be intellectually honest and rethink how you are classifying individuals so you don’t stigmatize them with the label of cancer,” he said. “The paper makes a good point that this subgroup of patients doesn’t require aggressive therapy.

“This is part of a general trend of de-escalating treatment of thyroid cancer in general and all to the good,” he said.