The Rising Incidence of Thyroid Cancer

It’s easy to crunch the numbers on thyroid cancer and assume it is a disease fast on the rise. Incidence has more than doubled since the early 1970s, and for women, it is the cancer with the fastest-growing number of new cases.

But not every statistic tells the obvious tale. Despite the increase, thyroid cancer - a very treatable disease that develops in a butterfly-shaped gland in the neck — is still relatively uncommon.

Many people develop benign lumps, known as nodules, in the neck, but only one in 20, or less than 45,000 cases a year, are malignant. Even fewer patients have an aggressive form of the disease, which has a survival rate of nearly 97 percent after five years and results in an estimated 1,690 deaths each year. Over the last few years, however, studies showing there has been a significant increase in incidence, and even mortality, in certain groups have caused much debate in the scientific community.

“I don’t think there is any question that there is an increasing incidence of thyroid cancer,” said Dr. Kenneth Burman, chief of the endocrine section in the department of medicine at Washington Hospital Center in Washington, D.C. “But it is not that simple. The question is whether or not it is related to detection and radiological studies, or if it is related to an authentic rise in thyroid cancer.”

It is a question that still remains largely unanswered. Evidence from the Surveillance, Epidemiology and End Results database, a registry of cancer cases that is kept by the National Cancer Institute, leaves little question that there are more cases of thyroid cancer today than three decades ago. But the more important question, as Dr. Burman points out, is whether these statistics indicate a true rise in the disease or are simply a result of better diagnostic tools.

Thyroid malignancy occurs with relative infrequency in the United States, although benign thyroid disease is relatively common. Although patients with thyroid cancers generally have a favorable prognosis compared with that of patients with many other solid tumors, an estimated 1200 patients died of thyroid cancer in the United States in 1998. Contemporary treatment of patients with thyroid malignancy requires a multidisciplinary approach involving an endocrinologist, a thyroid surgeon, a radiologist, and, on occasion, medical and radiation oncologists.

Over the last three decades, ultrasound and fine-needle biopsies have helped diagnose thousands of cases that would never have been found before. In many cases, nodules are discovered by accident during another medical investigation.

A study published in The Journal of the American Medical Association first brought this issue to light in 2006. Researchers concluded that the reported 140 percent increase in thyroid cancer from 1973 to 2002 was simply a result of “increased diagnostic scrutiny.”

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