Analysis of Risk Factors for Lymph Node Metastases in Elderly Patients with Papillary Thyroid Micro-Carcinoma

Background: With guidance from the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, 8th edition, we explored the characteristics of central lymph node metastasis (CLNM) of papillary thyroid micro-carcinoma (PTMC) in elderly patients >= 55 years of age. Our goal was to provide references for establishing a lymph node dissection scheme in such patients. Methods: We retrospectively analyzed the clinical data of thyroid cancer patients admitted to the Head and Neck Surgery Center of Sichuan Cancer Hospital, Chengdu, China, from January 2015 to September 2018. Then, we screened and analyzed eligible PTMC cases in strict accordance with our inclusion and exclusion criteria. Results: The study included 107 patients, including 24 men and 83 women. Median age was 59.99 +/- 4.58 years. The maximum diameter range of the cancer foci was 4-10 mm, and the median was 7.59 +/- 1.78 mm. Unilateral lobectomy had been performed in 32 cases, total thyroidectomy in 75 cases and lateral cervical lymph node dissection in 21 cases. There were 60 cases of CLNM (56.07%) and 13 cases of lateral cervical lymph node metastasis (12.10%). The sensitivity of preoperative ultrasound in predicting CLNM was 100%, but its accuracy was only 50.47%. Multivariate logistic regression analysis showed that multiple cancer foci (area under the curve [AUC] = 0.632), extra-thyroidal expansion of cancer focus (AUC = 0.721), and irregular nodules (AUC = 0.603) were independent risk factors for CLNM of PTMC in elderly patients (P < 0.05). Overall predictability for PTMC-CLNM was 80.30%. Conclusion: 1) Preoperative color Doppler ultrasound is not recommended as the basis for cervical lymph node dissection in PTMC patients. 2) For multiple cancer foci, irregular nodules, and elderly patients with PTMC extra-thyroidal expansion, we recommend a prophylactic central lymph node dissecting. 3) Nonsurgical observation of PTMC in elderly patients with low risk should be carefully selected.