BACKGROUND
Thyroid cancer is the most common endocrine cancer. Most thyroid cancer patients show excellent response to their initial treatment, and the overall prognosis is excellent. When thyroid cancer recurs, it usually recurs in the neck, whether in the thyroid bed where the original cancer was, or in the nearby lymph nodes in the neck. Surgery has traditionally been the standard treatment to remove this recurrent cancer. However, repeat surgeries can carry important risks, including permanent damage to the parathyroid glands (which help control calcium levels) and injury to the laryngeal nerve (which can lead to a hoarse voice).

Because of these concerns, some alternative approaches have been considered for selected patients with small, stable recurrences. One option is active surveillance, which involves closely monitoring the cancer with regular follow-up visits and imaging rather than treating it immediately. However, the evidence supporting active surveillance for recurrent thyroid cancer has limitations. Most published studies include a small number of patients followed for a limited time. These factors may underestimate the true risk of cancer progression, especially when patients are lost to follow-up or choose surgery before any progression is observed.

In this study, the researchers reviewed all of the prior studies with the goal of providing a more accurate estimate of the risk of cancer progression during active surveillance of patients with recurrent thyroid cancer.

THE FULL ARTICLE TITLE
Lim H et al. Active Surveillance for Locoregional Recurrent Differentiated Thyroid Cancer: A Systematic Review and Meta-Analysis. Thyroid. 2026 Feb;36(2):121- 132. doi: 10.1177/10507256251412323. Epub 2026 Jan 7. PMID: 41791888.

SUMMARY OF THE STUDY
The authors identified 10 studies including a total of 841 patients with thyroid cancer (predominantly papillary thyroid carcinoma) who had recurrence of their cancer in the neck area (thyroid bed nodules or lymph node in the neck) after undergoing surgical removal of the primary thyroid tumor. These patients were managed with active surveillance rather than immediate treatment, with an average follow-up period of 52 months. In most studies, 76-94% of patients received radioactive iodine treatment after the initial thyroid surgery.

The initial baseline cancer size ranged from 5 to 13 mm. Most studies excluded patients with large cancers (larger than 20-30 mm), potentially aggressive cancers or spread outside of the neck. The study evaluated the progression rate of recurrent thyroid cancer during active surveillance and identified factors associated with cancer progression.

Across all studies, approximately 23% of patients experienced cancer progression while under active surveillance. In studies where the recurrence was confirmed by biopsy, the progression rate was higher, reaching 32%. Studies that included fewer patients with early-stage cancer reported higher progression rates (30% vs. 11%). Similarly, studies with a greater proportion of patients with advanced stage cancer reported higher progression rates (28% vs. 14%). Interestingly, studies an average follow-up of less than 40 months reported higher progression rates than studies with longer follow-up (36% vs. 17%). The authors suggested that this finding may reflect differences in patient selection and study design rather than a true reduction in risk over time.

Patients whose had cancer progression had significantly higher baseline thyroglobulin levels, a blood marker commonly used to monitor thyroid cancer recurrence, compared with patients with stable cancer. Many of the included studies had substantial loss to follow-up, meaning that some patients stopped participating before the study ended. When the authors adjusted their analysis to account for the missing patients, the estimated progression rate increased considerably, ranging from 35% to 70%.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
When patients with recurrent thyroid cancers were carefully selected for active surveillance, about 23% showed progression their cancer. However, this figure is likely an underestimate because some patients were lost to follow-up, while others received surgery or other treatments before progression could be fully assessed. These findings suggest that active surveillance for recurrent thyroid cancer should be used cautiously. Patients with higher baseline Tg levels or more advanced cancer at diagnosis appear to have a greater risk of cancer progression and may require closer monitoring or earlier treatment.

— Elie Naous, MD
— Alina Gavrila, MD, MMSC

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