CLINICAL THYROIDOLOGY FOR THE PUBLIC
A publication of the American Thyroid Association
Summaries for the Public from recent articles in Clinical Thyroidology
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THYROID CANCER
Pregnancy does not increase the size of papillary thyroid microcarcinomas
BACKGROUND
Thyroid cancer is the fastest rising cancer in women. Since thyroid cancer is generally slow growing, some very small (<1cm) cancers are candidates for being watched and not operated on immediately (papillary microcarcinomas). However, for women with small thyroid cancers that become pregnant, there is concern that the pregnancy might cause such small cancers to grow. This is because of the high levels of pregnancy hormone known as hCG, which is known to stimulate growth of the thyroid gland. This study followed a group of pregnant women with small thyroid cancers that were being watched to see if pregnancy caused a growth in their cancers.
THE FULL ARTICLE TITLE:
Ito Y et al. Effects of pregnancy on papillary microcarcinomas of the thyroid re-evaluated in the entire patient series at Kuma Hospital. Thyroid 2016;26:156-60. Epub December 15, 2015.
SUMMARY OF THE STUDY
Over a 20-year period, 50 pregnant women at Kuma hospital in Japan with small thyroid cancers were followed during and after their pregnancy for growth of their thyroid cancers. All patients had an ultrasound to evaluate their small cancer within 1 year before their pregnancy and within 1 year after giving birth. Some patients also had an additional ultrasound during their pregnancy. The researchers were looking to see if the cancer grew by
3mm or more during the pregnancy. The same radiologist reviewed all of the images without knowing the dates of the studies or the names of the patients.
For 90% of the women, their small cancers did not change in size during their pregnancy. In 4 patients, the cancers grew by 3mm or more and 2 of those 4 patients then had surgery for their cancer (they were 1.7cm and 1.8cm) In 1 patient, the cancer actually shrunk by 3mm. Over the 20 years of the study, 6 more women had their thyroid removed for different reasons: 2 by choice, 1 for an overactive thyroid, 1 for an enlarging thyroid gland, and 2 after they were found to have abnormal lymph nodes during annual follow-up exams.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study shows that it is safe to watch small cancers during pregnancy. This means that if you have a known, small thyroid cancer it is ok to get pregnant. Moreover, if a small thyroid cancer is discovered during your pregnancy it is ok to wait until after surgery to have it treated.
— Melanie Goldfarb MD, MS, FACS, FACE
ATA THYROID BROCHURE LINKS
Thyroid Disease and Pregnancy: http://www.thyroid.org/thyroid-disease-pregnancy/
Thyroid Cancer: http://www.thyroid.org/thyroid-cancer/
ABBREVIATIONS & DEFINITIONS
Thyroid Ultrasound: a common imaging test used to evaluate the structure of the thyroid gland. Ultrasound uses soundwaves to create a picture of the structure of the thyroid gland and accurately identify and characterize nodules within the thyroid. Ultrasound is also frequently used to guide the needle into a nodule during a thyroid nodule biopsy.
Papillary microcarcinoma: a papillary thyroid cancer smaller than 1 cm in diameter.
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