Predictive Factors of Lymph Node Metastasis in Follicular Variant of Papillary Thyroid Carcinoma.

BACKGROUND: Compared with conventional papillary thyroid carcinoma (PTC), follicular variant of PTC (FV-PTC) shows less aggressive behavior and better prognosis. Nonetheless, regional lymph node (LN) metastasis was found in 22.8% of FV-PTC patients. Because LN metastasis is a proven predictor of recurrence in PTC, it is important to assess LN metastasis in FV-PTC patients. METHODS: We retrospectively reviewed 134 FV-PTC patients who underwent thyroidectomy with neck dissection. RESULTS: Central LN metastasis (CLNM) and lateral LN metastasis (LLNM) were found in 50 (37.3%) and 16 (11.9%) patients, respectively. In the multivariate analysis for CLNM, male sex (adjusted OR 4.735, p = 0.001), nonencapsulated form (adjusted OR 2.863, p = 0.022), and tumor size >1.0 cm (adjusted OR 3.157, p = 0.008) were independent predictors of high prevalence of CLNM in FV-PTC patients. In the multivariate analysis for LLNM, microscopic extrathyroidal extension (ETE) (adjusted OR 3.939, p = 0.041) and CLNM (adjusted OR 13.340, p = 0.001) were independent predictors of high prevalence of LLNM in FV-PTC patients. CONCLUSIONS: Meticulous perioperative evaluation and prophylactic central neck dissection may be beneficial for FV-PTC patients with male sex, nonencapsulated form, and tumor size >1.0 cm. Moreover, cautious perioperative evaluation of lateral neck LN may be mandatory for FV-PTC patients with microscopic ETE and CLNM.

Patterns, Predictive Factors, and Prognostic Impact of Contralateral Lateral Lymph Node Metastasis in N1b Papillary Thyroid Carcinoma.

BACKGROUND: Although the incidence among patients with bilateral lateral lymph node metastasis (LLNM) in N1b papillary thyroid carcinoma (PTC) is reported to be as high as 40%, only a few reports have addressed the characteristics of contralateral LLNM. Therefore, this study aimed to investigate the characteristics of patients with contralateral LLNM in N1b PTC. METHODS: This study retrospectively reviewed 834 patients with N1b PTC who underwent modified radical neck dissection between January 1997 and June 2015. RESULTS: Of the 834 N1b PTC patients, unilateral LLNM was found in 728 patients (87.3%) and bilateral LLNM in 106 patients (12.7%). The independent predictors of contralateral LLNM in N1b PTC patients were male sex (adjusted odds ratio [OR], 1.647; p = 0.039), tumor larger than 4 cm (adjusted OR, 6.700; p < 0.001), multiplicity (adjusted OR, 1.754; p = 0.040), bilobar involvement (adjusted OR, 1.971; p = 0.010), and bilateral central LN metastasis (CLNM) (adjusted OR, 2.829; p = 0.025). Moreover, contralateral LLNM significantly increased the risk of overall (adjusted hazard ratio [HR], 1.943; p = 0.016) and lateral neck (adjusted HR, 2.246; p = 0.015) locoregional recurrence. CONCLUSIONS: In the preoperative period, the meticulous evaluation of contralateral lateral neck may be required for male N1b PTC patients with tumor larger than 4 cm, multiplicity, bilobar involvement, and/or bilateral CLNM. In the postoperative period, N1b PTC patients may be re-stratified according to the contralateral LLNM, and meticulous follow-up assessment is required for N1b PTC patients with contralateral LLNM.

Should Level V Be Routinely Dissected in N1b Papillary Thyroid Carcinoma?

BACKGROUND: For N1b papillary thyroid carcinoma (PTC) patients, modified radical neck dissection (MRND) encompassing levels II-V is generally recommended. However, routine level V dissection is controversial because of the low incidence of metastasis/recurrence in level V and the increased morbidities associated with level V dissection. METHODS: This study retrospectively reviewed 646 N1b PTC patients who underwent unilateral MRND between January 1997 and June 2015. Specifically, to assess surgery-related outcomes of level V dissection, outcomes from N1b PTC patients who underwent unilateral MRND (levels II-V) were compared with those who underwent unilateral selective neck dissection (SND; levels II-IV) using propensity score matching. RESULTS: Overall and occult level V metastases were observed in 13.9% and 8.6% of patients, respectively. Level V recurrences were observed in only 2.26 (7.7%) recurred N1b PTC patients who underwent unilateral MRND. In multivariate analysis, three-level (II, III, and IV) simultaneous metastasis (adjusted odds ratio = 3.079, p = 0.003) was an independent predictor for level V metastasis. Under a matched condition, "shoulder syndrome" encompassing shoulder dysfunction and pain (9.1% vs. 2.7%, p = 0.002) was significantly more frequent in the MRND group than it was in the SND group. CONCLUSIONS: Because of the low incidence of metastasis/recurrence in level V and the clear evidence of increased morbidities, level V dissection in N1b PTC patients may be reserved for those with three-level simultaneous metastasis or clinically/radiologically evident level V metastasis.

Routine Level 2b Dissection may be Recommended Only in N1b Papillary Thyroid Carcinoma with Three- or Four-Level Lateral Lymph Node Metastasis.

BACKGROUND: Due to the low incidence of level 2b metastasis and the risk of spinal accessory nerve injury, previous studies have argued against routine level 2b dissection for N1b papillary thyroid carcinoma (PTC). However, other studies have suggested the importance of including level 2b during lateral neck dissection. Therefore, this study aimed to determine the necessity of routine level 2b dissection. METHODS: The study retrospectively reviewed 327 N1b PTC patients who underwent unilateral modified radical neck dissection between January 1997 and May 2016. RESULTS: The incidence of level 2b metastasis was 10.4 %, compared with 53.5 % for level 2a metastasis. The univariate analysis showed that large tumor size (p = 0.027) and simultaneous lateral lymph node metastasis (LLNM) (p = 0.002) were significantly associated with level 2b metastasis. The multivariate analysis showed that three-level (adjusted odds ratio [OR] 6.032; p = 0.020) and four-level (adjusted OR 9.398; p = 0.012) simultaneous LLNM were independent predictors for level 2b metastasis. CONCLUSIONS: Due to the low incidence of level 2b metastasis, routine level 2b dissection may not be necessary for N1b PTC patients. Level 2b dissection may be reserved for patients with more than three-level simultaneous LLNM or clinical/radiological evidence of level 2b metastasis.