Clinical and morphological factors that increase the risk of locoregional metastasis of papillary thyroid cancer

Background. The sensitivity of the ultrasound method to determine lymph node metastases of papillary thyroid cancer (PTC) to the central lymphatic collector of the neck at the preoperative stage is low, 49 % only, therefore assessment of the factors leading to the prolongation of the process is of great importance in the development of surgical treatment tactics.Aim — to evaluate factors that increase the risk of locoregional metastases of papillary thyroid cancer and substantiate the advisability of systematic central neck dissection (SCND).Materials and methods. A retro-prospective single center study of the risk of PTC prolongation in the form of locoregional metastases (LRM) was carried out. The data of 514 patients operated for papillary thyroid disease were processed. The main group included 240 patients in whom LRM was found according to the results of histopathological examination (HPE), control group consisted of 274 patients without LRMsigns. The following signs were taken into account: multifocal lesions of the thyroid gland, the patients’age, gender, presence of thyroiditis, the size of the dominant tumor, invasion of adipose tissue. In order to substantiate the expediency of the SCND, retrospective processing of the data of 514 patients, operated from 2018 to 2020, was carried out for PTC, in which the presence of metastases was not cytologically confirmed at the preoperative stage (cN0).Results. The mean age of patients of the main group was lower than in the control group (p < 0.001). The median size of the primary tumor in patients of the main group was significantly higher than in the control group (p < 0.001). The men portion in the main group was significantly higher than in the control group, and the part of women vice versa (p < 0.05). Invasion of the tumor into the adipose tissue in the main group occurred almost twice as often (p < 0.01). The number of patients with multifocal lesions in both groups was practically the same and did not differ statistically (p > 0.05). Ipsilateral and contralateral localization of tumors in both groups did not differ significantly (p > 0.05). The presence of thyroiditis in the control group was higher than in the main group (p < 0.05). The diagnostic efficiency (DE) of accounting for the factor of invasion into adipose tissue was 64.8 %, tumor size over 1.3 cm — 66.7 %, age up to 47 years — 60.0 %. The frequency of detecting metastases with cN0 at the preoperative stage, according to HPE results, was 25.8 %.Conclusions. The reliability of preoperative imaging and diagnostic methods does not allow to ignore the likelihood of LRM and not perform SCND. According to the obtained data, in 25.8 % of casesmetastases were verified based on HPE owing to thesystematic central neck dissection. Male gender (p < 0.01), age of patients (p < 0.001), size of primary tumor (p < 0.001), invasion of adipose tissue (p < 0.01) can serve as predictors of the increased LRMPTC risk. The presence of invasion of adipose tissue (diagnostic efficacy 64.8 %), tumor size more than 1.3 cm (66.7 % DE) and age < 47 (60.0 % DE) increased the risk of LRMPTC. The presence of thyroiditis (the frequency of thyroiditis exposure in control group was higher than in the main group (p < 0.05)), contralateral lesions of the thyroid gland (p > 0.05), multifocal lesions (p > 0.05) cannot serve as reliable prognostic factors for the increased LRMrisk.