Abstract
For detecting tumor recurrence of medullary thyroid carcinoma (MTC) in the neck, an appropriate frequency and interval of postoperative ultrasonography (US) surveillance remains unclear. This study aimed to assess an appropriate interval and frequency of postoperative neck US surveillance for detecting tumor recurrence in patients who had undergone thyroid surgery due to MTC. A total of 86 patients who had undergone thyroid surgery for the treatment of MTC and had at least one postoperative US follow-up examination at any of nine affiliated hospitals were included. Postoperative follow-up US, clinical, and histopathological results of patients were reviewed. The tumor recurrence/persistence rate of MTC was investigated, and the interval and session number of postoperative follow-up US and clinicopathologic factors were compared between tumor recurrence/persistence and non-recurrence groups. Of the 86 patients, 22 (25.6%) showed tumor recurrence/persistence. Of the 22 patients with tumor recurrence/persistence, 11 (50%) showed structural recurrence/persistence in the neck on follow-up US. In these 11 patients, the mean interval and session number of postoperative follow-up US between initial surgery and the first US detection of recurrence/persistence was 41.3 ± 39.3 months (range, 6-128 months) and 2.6 ± 2.3 (range, 1-8), respectively. On follow-up US, 6 (54.5%, 6/11) were diagnosed with tumor recurrence/persistence within 3 years of the initial surgery. Tumor recurrence/persistence was significantly correlated with TNM stage (p < 0.001) and multiplicity/bilaterality (p = 0.013). For detecting MTC recurrence/persistence, postoperative US surveillance at 1-year intervals may be sufficient within the first 3 years after thyroid surgery, but depending on the presence of relevant risk factors, annual or biannual US surveillance may be recommendable for 4-10 years after thyroid surgery.
Highlights
Medullary thyroid carcinoma (MTC) is an uncommon thyroid cancer which accounts for 3–10% of all thyroid cancers [1, 2]
Older age at diagnosis, and more advanced primary tumor or nodal stage have been proposed as prognostic factors for adverse outcomes [8, 9]
Distant metastasis, advanced age, primary tumor stage, and nodal stage have been proposed as prognostic factors [7,8,9]
Summary
Medullary thyroid carcinoma (MTC) is an uncommon thyroid cancer which accounts for 3–10% of all thyroid cancers [1, 2]. The prognosis of MTC is intermediate between differentiated and anaplastic thyroid carcinomas [1]. Distant metastasis, which is reportedly observed at initial presentation in 7–23% of patients, is known to be the main cause of MTC-related mortality [7]. Serum kinetics of MTC markers, such as calcitonin and carcinoembryonic antigen, may be alternative predictors of survival [10]. For detecting tumor recurrence of medullary thyroid carcinoma (MTC) in the neck, an appropriate frequency and interval of postoperative ultrasonography (US) surveillance remains unclear.
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