A new study in published Thursday in JAMA Otolaryngology - Head and Neck Surgery suggests that the cases of diagnosed thyroid cancer have tripled since 1975.

Researchers at Dartmouth's Geisel School of Medicine suggest that the increase in the cases of thyroid cancer was due largely to the diagnosis and treatment of small, slow-growing tumors or over-diagnosis of thyroid cancer because the death rate has not changed.

The fact that the rate of death from thyroid cancer remained the same and the increased cases were largely small, slow-growing tumors could also indicate that the current treatment of early diagnosed thyroid cancer is not better than the old treatment at reducing death risk from thyroid cancer.

The thyroid gland is one of the largest endocrine glands which is located in the neck, below the thyroid cartilage and it regulates the use of energy and protein synthesis, and controls the body sensitivity to other hormones.

The study also found the absolute increase in diagnosed thyroid cancer cases in women was four times higher than that observed in men.

One thing that women but not men often do is use mammography for the breast cancer screening.  The thyroid gland is very sensitive to radiation and it's known that exposure to x-ray can increase the risk of thyroid cancer.  Theoretically, any residual radiation from mammography can increase the risk.

Studies also suggest that hormone replacement therapy may also increase the risk of thyroid cancer.  One study in Cancer Prevention Research found women exposed for high estrogen for longer periods were at higher risk for thyroid cancer.  (David Liu)