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Pregnancy does not affect progression of thyroid cancer

Clinical Thyroidology for the Public

The rate of thyroid cancer is increasing in women of childbearing age, so it is not surprising that thyroid cancer is occasionally diagnosed during pregnancy. It is unclear whether pregnancy affects the response of thyroid cancer to treatment or the risk of recurrence of thyroid cancer. The risk assessments for thyroid cancer have changed over the past few years and the risk for recurrence is now reassessed two years after the initial surgery based on how they responded to their initial therapy. However, the initial risk assessment guidelines did not address pregnant women since no studies had evaluated this particular group of patients. Therefore, this study wanted to see if the risk assessment classifications, both initial and two years later, were the same for pregnant women.

Rakhlin L et al Response to therapy status is an excellent predictor of pregnancy-associated structural disease progression in patients previously treated for differentiated thyroid cancer. Thyroid. January 19, 2017 [Epub ahead of print].

A total of 235 women with a history of thyroid cancer and pregnancy treated at Memorial Sloan Kettering in New York were evaluated. Of these, 90% had a total thyroidectomy and 61% received radioactive iodine therapy. Patients were assigned risk categories based on blood tests for thyroglobulin and evidence of cancer in the neck by some form of imaging (usually ultrasound). Abnormal lymph nodes in the neck was the evidence for cancer in the neck. All patients had levels determined within 1 year prior to pregnancy and within 1 year after delivery.

At evaluation after delivery, no woman without abnormal lymph nodes after initial therapy developed abnormal lymph nodes after pregnancy. In increase of abnormal lymph nodes occurred in about 30% of women that still had abnormal lymph nodes after initial treatment. Additionally, 52% of women where it was unclear if there were abnormal lymph nodes before pregnancy had no evidence of thyroid cancer recurrence after pregnancy.


This study suggests that development of abnormal lymph nodes during pregnancy is rare and happens in less than 5% of women. Young women with a history of thyroid cancer do not need to worry that pregnancy will cause their thyroid cancer to grow to anything that changes their risk status. However, studies with longer term follow-up are needed.

— Melanie Goldfarb, MD

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Thyroid Cancer (Papillary and Follicular): http://www.

Thyroid Disease and Pregnancy: thyroid-disease-pregnancy/


Papillary thyroid cancer: the most common type of thyroid cancer. There are 4 variants of papillary thyroid cancer: classic, follicular, tall-cell and noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).

Total thyroidectomy: surgery to remove the entire thyroid gland.

Thyroglobulin antibodies: these are antibodies that attack the thyroid instead of bacteria and viruses, they are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.

Thyroglobulin: a protein made only by thyroid cells, both normal and cancerous. When all normal thyroid tissue is destroyed after radioactive iodine therapy in patients with thyroid cancer, thyroglobulin can be used as a thyroid cancer marker in patients that do not have thyroglobulin antibodies.

Radioactive iodine (RAI): this plays a valuable role in diagnosing and treating thyroid problems since it is taken up only by the thyroid gland. I-131 is the destructive form used to destroy thyroid tissue in the treatment of thyroid cancer and with an overactive thyroid. I-123 is the non-destructive form that does not damage the thyroid and is used in scans to take pictures of the thyroid (Thyroid Scan) or to take pictures of the whole body to look for thyroid cancer (Whole Body Scan).

Cancer recurrence: this occurs when the cancer comes back after an initial treatment that was successful in destroying all detectable cancer at some point.