Study: Treating thyroid cancer during pregnancy can entail serious risks

Papillary thyroid cancer is the most common form of thyroid cancer, both in the general U.S. population and among pregnant women. A review of the medical options available during gestation indicates that treating thyroid cancer during pregnancy can cause several serious complications.

In a case study published in the Journal of Clinical Endocrinology and Metabolism, professor of medicine Ernest Mazzaferri analyzed how a 24-year-old woman who was diagnosed with a papillary thyroid carcinoma dealt with the disease before giving birth.

He wrote that she had been aware of a lump in her neck for about a year before seeing a specialist about it. The tumor turned out to be a papillary nodule about one inch in diameter. After discussing the potential side effects of surgical removal or radioactive iodine therapy, the woman decided to postpone medical intervention until after having her baby.

Three months after delivery, she underwent a total thyroidectomy.

Mazzaferri notes that, of women diagnosed with cancer during pregnancy, approximately 10 percent have a thyroid carcinoma. A study published in the same journal in 1997 stated that an estimated one in every 1,000 pregnant women has some form of thyroid cancer.

Previous research has suggested that the incidence of thyroid cancer may actually increase during pregnancy due to elevated levels of estrogen and human chorionic gonadotropin, a hormone associated specifically with gestation.

A review of women treated for thyroid cancer, which was published in the journal Endocrine Abstracts, determined that those treated during pregnancy are more likely to see a recurrence of the disease, often as a metastasis in the salivary glands or lymph nodes.

There are several dangers to a fetus caused by treatments for this disease. Surgery performed during pregnancy carries a risk of spontaneous abortion or of contributing to breech birth, Mazzaferri states.

After a thyroidectomy, pregnant women must take thyroid hormone replacement, without which a fetus may develop abnormally.

The authors conclude that the safest course of action is to wait until after delivery to undergo surgery for thyroid cancer.

Women are three times more likely than men to be diagnosed with the disease. More than 15 in every 100,000 women will be diagnosed with thyroid cancer every year, according to the National Cancer Institute.