Influence of lymph node metastases on survival in pediatric medullary thyroid cancer

Purpose: Lymph node metastases (LNM) from medullary thyroid cancer (MTC) are common in adults and are a poor prognostic factor. Less is known about LNM in children, who often have hereditary forms of MTC. Guidelines recommend prophylactic thyroidectomy in early childhood, but randomized prospective trials are not feasible. We hypothesized that LNM is associated with poor prognosis in children. Methods: Patients with MTC 21 years or younger from the National Cancer Data Base from 1985 to 2007 were studied. Multivariable logistic regression was used to identify factors associated with lymph node evaluation. Survival was estimated using the Kaplan-Meier method. Results: Of 430 patients, 276 (64.2%) had nodal evaluation with LNM present in 121 (28.1%). Older patients, those with tumors larger than 2 cm, and those with involved margins were more likely to have LNM (all P < .05). Patients undergoing total thyroidectomy, those with involved margins, and older patients were more likely to undergo lymph node evaluation after controlling for patient, tumor, and hospital factors (all P < .05). Over time an increasing number of patients with MTC have undergone total thyroidectomy. Patients 16 to 21 years of age had lower 10-year overall survival compared to patients 0 to 15 years old (88.7% vs 98.1%, P = .005). Lymph node metastases were also associated with decreased 10-year overall survival (84.4% vs 100%, P < .001). Conclusions: In pediatric MTC, LNM predict poorer overall survival. Adequate lymph node assessment can provide valuable prognostic information for the pediatric MTC patient. Lymph node assessment should be considered for older pediatric patients undergoing surgery for hereditary MTC or biopsy confirmed MTC.