Response to Treatment is Highly Predictable in cN0 Patients with Papillary Thyroid Carcinoma

While involvement of macrometastatic lymph nodes is a recognized independent predictor of an adverse course in papillary thyroid cancer (PTC) patients, the clinicopathological variables associated with disease persistence/recurrence in clinically node-negative (cN0) disease are not well defined. The indications for prophylactic central neck dissection (pCND) in this patient group remain unclear as well. We aim to investigate the risk factors associated with short- and long-term persistence/recurrence of PTC in patients with cN0 disease at presentation compared to patients with PTC and cervical lymph node involvement (N1) and the response to initial treatment in these subgroups of patients.

Data were collected retrospectively for 392 consecutive patients with PTC, 223 with cN0 disease and 169 with N1 disease, who were treated and followed at a single tertiary medical center in which pCND is not routinely performed for PTC.

Compared to patients with N1 disease, patients with cN0 disease had significantly smaller tumors, lower rates of multifocality, and less extrathyroidal extension. Persistency rates at 1 year were 6.7 % in the cN0 group and 47 % in the N1 group, and at last follow-up, 3.6 and 33.5 %, respectively (p = 0.001 for both time points). Within the cN0 group, those with persistent disease at 1 year (n = 15) had significantly larger tumors and higher stimulated thyroglobulin. Only six had structural residual disease, four of them lymph node metastases. All patients with persistent disease were initially treated with total thyroidectomy and radioiodine. Recurrence occurred in only three patients. After 8.3 ± 3.8 years of follow-up, eight patients with cN0 had persistent disease, three of them biochemical. Higher American Joint Committee of Cancer stage and extrathyroidal extension were the only factors that predicted disease persistence at the last follow-up in this group.

Patients with cN0 PTC and no distant metastases are usually disease free after thyroidectomy with/without radioactive iodine and do not need further interventions. The initial staging in these patients is a valid prognostic factor for disease outcomes.