BACKGROUND
The development of nodules inside the thyroid gland, a butterfly-shaped organ in the front part of the neck that makes thyroid hormone, is very common. While the vast majority of thyroid nodules are benign (not cancerous), many thyroid nodules are biopsied to determine which may be cancerous. When these biopsies show thyroid cancer, or are suspicious for thyroid cancer, thyroid surgery is usually performed to remove at least that part of the thyroid containing the cancerous/possibly cancerous growth. This is done to prevent a thyroid cancer from growing and/or spreading to other parts of the body, which might cause significant illness or even death.

Several recent studies, however, suggest that when a thyroid cancer is very small (less than 1 cm in diameter, called microcarcinomas), most will never grow or spread to other parts of a person’s body. For this reason, some doctors are now recommending watching these small thyroid cancers over time with ultrasound imaging (which is the best way to look at the thyroid), deferring surgery until the small cancer starts to grow. This is called active surveillance. Because most of these small cancers do not grow, or show evidence of trying to spread out of the thyroid over time, many people who have these small cancers might be able to avoid thyroid surgery.

Because of these findings, some researchers, are now interested in knowing if larger thyroid cancers, or larger nodules that are suspicious for cancer after a biopsy, may also be safely watched over time by ultrasound imaging. This study examined the results of active surveillance with nodules >1 cm that are either cancerous or suspicious for cancer.

THE FULL ARTICLE TITLE
Altshuler B et al. Non-operative, active surveillance of larger malignant and suspicious thyroid nodules. J Clin Endocrinol Metab. Epub 2024 Feb 13:dgae082. doi: 10.1210/clinem/dgae082. PMID: 38349208.

SUMMARY OF THE STUDY
The authors of this work identified 69 adults who were diagnosed with a thyroid nodule > 1 cm and for which a biopsy showed either thyroid cancer, was suspicious for cancer, between the years of 2001 and 2021. The people studied had not undergone thyroid surgery because of underlying health problems that might have made surgery too dangerous or because they voluntarily chose not to undergo thyroid surgery. Most of the people in the study were women (56 of 69). The thyroid nodule was >1 cm but <2 cm for 58 (84%) of the people studied, while the nodule was > 2 cm for the remaining 11 (16%) people in the group. The thyroid nodule biopsy showed thyroid cancer for 14 people in the study, with the remaining 55 having biopsies suspicious for thyroid cancer. The study group was monitored with repeated ultrasound imaging for an average of 55 months (about 5 years).

Over the average time of about 5 years, 15 people in the study were found to have significant increase in the size of their thyroid nodule (by at least 0.3 cm) and 17 study members had their nodules increase in volume by at least 50%. Overall, 13 people in the study ended up having thyroid surgery, and 9 of these proved to be cancerous when the removed thyroid was analyzed after surgery. None of the people in the study died of thyroid cancer or were found to have evidence of thyroid cancer spread to other parts of the body during the study period.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study suggests that some thyroid cancers >1 cm in size may not need to undergo immediate surgical removal after being diagnosed by biopsy and can be followed by active surveillance. It is very important to understand that much bigger studies are needed to verify that thyroid cancers >1 cm can be safely watched over time instead of being removed surgically, which is generally safe and effective when performed by a surgeon who specializes in thyroid surgery. It is also very important to understand that there are no effective medicines for treating thyroid cancer and that thyroid cancer, if not removed with surgery, might grow and spread, ultimately causing significant illness or even death.

— Jason D. Prescott, MD PhD

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