Pattern of Lymph Node Metastasis on the Prophylactic Central Neck Node Dissection in Management of Papillary Carcinoma of Thyroid / 대한내분비외과학회지

ABSTRACT

PURPOSE: In papillary thyroid carcinoma, lymph node metastasis at presentation does not seem to affect survival adversely, but does increase the risk of loco-regional tumor recurrence. The benefits of prophylactic central neck node dissection (PCND) have not been clearly demonstrated so far and should be weighed against the potential risks of the procedure. The aims of this study are as follows; to determine the frequency and the pattern of the lymph node metastasis and the risk factors influencing the metastasis to level VI lymph nodes, and to determine the necessity of the contralateral central lymph node dissection. METHODS: A retrospective analysis had been carefully performed over 68 patients with papillary carcinomas undergoing total thyroidectomy with PCND during the period from July 1, 2000 to August 31, 2002. In addition to the analyses of the incidence and the pattern of central lymph node metastasis, we statistically analyzed the correlation between lymph node metastases and the risk factors such as tumor size, age, lymphatic tumor emboli, vascular tumor emboli, perithyroidal soft tissue invasion, and multifocality, etc. RESULTS: The mean age was 46 years (22~76) and the tumor size ranged from 0.2 to 9 cm (mean 2.2 cm). The micropapillary carcinoma was detected by pathological findings in 10 patients (14.7%). The lymphatic tumor emboli and vascular tumor emboli occurred in 8 patients (11.8%) and 2 patients (2.9%) respectively. Thirty eight patients (55.9%) showed perithyroidal tissue invasion. The mean number of harvested lymph nodes in level VI was 13.7 (6~32). Among 68 patients, lymph node metastasis occurred in 49 patients (72.1%) and the mean number of metastatic lymph node was 5.4. Among the patients with metastasis, the rate of metastasis among the harvest nodes amounted to 39.0%. Metastasis to Delphian nodes was detected in 2 patients (2.9%). In addition, 15 patients (22.1%) showed metastatic contralateral central nodes. Patients less than 40 years old tend to have more metastatic lymph nodes (P=0.012). Futhermore, the patients with tumor larger than 2 cm increased incidence of lymph node metastasis (P=0.036). CONCLUSION: After the prophylactic central neck nodes dissection in case of papillary carcinoma patients, metastatic lymph nodes were found in 72.1%. In conclusion, we would like to recommend prophylactic central neck node dissection to papillary carcinoma patients in order not only to prevent local recurrence but to avoid the difficulties of reoperation, especially for those with high risk for nodal involvement (less than 40 years old or more than 2 cm of tumor size). Because of the relatively high incidence of contralateral central lymph nodes metastasis, we suggest the importance of dissection of contralateral central lymph nodes along with unilateral central.