Abstract
Simple SummarySurgery is the only curative treatment for medullary thyroid carcinoma (MTC), but the initial surgical extent is still controversial. We examined whether the preoperative serum calcitonin level reflects the extent of lymph node metastasis (LNM), and therefore might be used to predict the optimal initial surgical extent for MTC. Furthermore, positive and negative likelihood ratios for preoperative serum calcitonin were calculated for calcitonin concentration categories, revealing that serum calcitonin levels can be of diagnostic value and might be applicable to surgical decision-making.The optimal initial surgical extent for medullary thyroid carcinoma (MTC) remains controversial. Previous studies on serum calcitonin are limited to reporting the calcitonin threshold according to anatomical disease burden. Here, we evaluated whether preoperative calcitonin levels can be used to predict optimal surgical extent. We retrospectively reviewed the 170 patients with MTC at a tertiary Korean hospital from 1994 to 2019. We extracted data on preoperative calcitonin level, primary tumor size and the number and location of lymph node metastases (LNMs). To evaluate disease extent, we divided the patients into five groups: no LNM, central LNM, ipsilateral lateral LNM, contralateral lateral LNM, and distant metastasis. We calculated the positive and negative likelihood ratios (LRs) for multiple categories of preoperative calcitonin levels. Preoperative calcitonin level positively correlated with primary tumor size (rho = 0.744, p < 0.001) and LNM number (rho = 0.537, p < 0.001). Preoperative calcitonin thresholds of 20, 200, and 500 pg/mL were associated with the presence of ipsilateral lateral LNM, contralateral lateral LNM, and distant metastasis, respectively. The negative LRs were 0.1 at a preoperative calcitonin cut-off of 100 pg/mL in the central LNM, 0.18 at a cut-off of 300 pg/mL in the ipsilateral lateral LNM, and 0 at a cut-off of 300 pg/mL in the contralateral lateral LNM. The preoperative calcitonin level correlates with disease extent and has diagnostic value for predicting LNM extent. Our results suggest that the preoperative calcitonin level can be used to determine optimal initial surgical extent.
Highlights
Medullary thyroid carcinoma (MTC) accounts for 1–2% of all thyroid carcinomas in the UnitedStates, and 0.4–2.2% of all thyroid carcinomas in Korea [1,2,3]
The group with a node stage below N1b had a higher proportion of females, a smaller primary tumor size, lower preoperative serum calcitonin levels and a lower number of lymph node metastases (LNMs) compared to the group with a node stage above N1b (Table 1)
The results from this study showed that preoperative serum calcitonin levels exceeding 20 and 200 pg/mL were associated with ipsilateral lateral LNM and contralateral lateral LNM, respectively, which is consistent with the findings of a previous study [17]
Summary
0.4–2.2% of all thyroid carcinomas in Korea [1,2,3]. The 10-year survival rate for the MTC is. 75–85%, whereas the 10-year survival is about 90% for papillary thyroid carcinoma [4,5,6]. It occurs as both a sporadic and a familial disease, and in families, MTC can occur alone or in combination with multiple endocrine neoplasia type 2A (MEN-2A) or MEN-2B [2]. MTC arises from thyroid parafollicular cells (C cells), which secrete several hormones, including calcitonin. Calcitonin is a 32-amino acid monomeric peptide that is used as a highly sensitive and specific tumor marker for MTC [7,8]. The current American Thyroid Association (ATA) guidelines recommend measuring the serum calcitonin level when patients are diagnosed with histological
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