BACKGROUND
Thyroid cancer is very common. Fortunately, most cases of thyroid cancer are low risk cancers with an excellent prognosis. This is especially true for small papillary thyroid cancers. The management of low risk thyroid cancers has been changing and immediate surgery is no longer the only option. Following low risk thyroid cancers (single cancers <1 cm with no evidence of spread of the cancer outside of the thyroid) with ultrasounds once or twice a year, known as active surveillance, has been shown to be a safe option. If the cancer grows or changes during active surveillance, then the next step is proceeding to surgery. In 2015, the American Thyroid Association (ATA) updated their guidelines to support active surveillance of low risk thyroid cancer as an alternative to surgery.

This study was done to provide information for further updates to these guidelines an answer two main questions: (1) what are the outcomes of performing surgery versus active surveillance of low risk thyroid cancer and (2) what are the results seen in studies that do not have a clear plan for close monitoring of these patients?

THE FULL ARTICLE TITLE
Chou R et al. 2022 Active surveillance versus thyroid surgery for differentiated thyroid cancer: A systematic review. Thyroid. Epub 2022 Jan 26. PMID: 35081743.

SUMMARY OF THE STUDY
Researchers performed an organized review of 27 publications that described studies in which patients underwent active surveillance of low risk thyroid cancer with neck ultrasound every 6-12 months then underwent surgery if there was cancer growth or patient preference. They looked at the risk of the cancer coming back (recurrence) and death, as well as growth of the cancer, need for surgery, spread of the cancer outside the thyroid, quality of life and harms of surgery.

To answer the question of performing surgery versus active surveillance, the review included studies that in sum had > 6,000 patients, from Japan, South Korea, United States, Colombia and Brazil, predominantly middle aged (44-57 years (mostly women)), and a duration of follow-up between 2-7 years. The results of these indicated that there was a similar low risk for death, spread of the cancer outside the thyroid and cancer recurrence in patients who had active surveillance versus immediate surgery. Most decisions to proceed with surgery were related to patient choice rather than cancer progression. Importantly, even though surgery may have complications, such as temporary hoarse voice or low calcium levels and an increased probability of receiving thyroid hormone replacement, no significant differences were seen in quality of life scores between both groups.

To answer the question of outcomes in studies that do not report clear protocols for active surveillance, the review included four studies in 88,654 patients, from the United States, predominantly aged 55-61 (with one study that had an average age of 72), also predominantly women with a follow up of 4.2-5.3 years. The results of these studies showed that surgery was associated with an improved all-cause and thyroid cancer related risk of death compare to no surgery.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This review suggests that there are similar risks of death, cancer recurrence and other outcomes in patients who had active surveillance versus immediate surgery as long as there are clear protocols to follow patients undergoing active surveillance. However, the limitations of the methods used in these studies does not allow strong conclusions to be made. It is important that patient understand their options regarding management of small, low risk thyroid cancer. Overall, active surveillance may be a safe alternative to immediate surgery and a conversation between patients and their physician regarding their own goals of care are the best way to making an appropriate decision.

— Maria Brito, MD

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