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OBJECTIVE Evidence for American Thyroid Association (ATA) risk stratification stems largely from studies involving patients undergoing total thyroidectomy. We aimed to assess the risk of recurrence according to the present ATA risk stratification system in patients who underwent lobectomy. DESIGN Retrospective cohort study. PATIENTS Patients who underwent thyroid lobectomy for 1-4 cm-sized papillary thyroid carcinoma (n = 571). MEASUREMENTS Disease-free survival (DFS) was compared according to the ATA risk stratification, and specific lymph node (LN) characteristics were evaluated to modify the ATA criteria with a higher predictability for recurrence. RESULTS Based on the ATA risk stratification, 439 patients (61.1%) were classified into intermediate- or high-risk group, and consideration for completion thyroidectomy is suggested by ATA guidelines for these patients. However, no significant differences were found in DFS among the low-, intermediate- and high-risk groups (P = .9). In contrast, when patients were stratified according solely to the LN criteria from the ATA risk stratification, only 127 patients (22.2%) had intermediate risk (intermediate-N1a) and exhibited significantly poorer DFS than those with N0 disease (P = .035). Modifying the intermediate-N1a criteria by adding the extranodal extension (ENE) status and omitting the clinical nodal disease enabled the subclassification of 19 patients (3%) with a high risk for recurrence. CONCLUSIONS The present study suggests that risk stratification based solely on LN metastases is more reasonable for predicting structural persistence/recurrence following lobectomy than that based on the overall ATA criteria. Considering the ENE status can assist in selecting patients with a high risk of recurrence to minimize further treatments.

SummaryObjective Previous studies did not focus on the differences in the extent of cervical lymph node (LN) dissection according to coexistent Hashimoto's thyroiditis (HT) in patients with papillary thyroid carcinoma (PTC) and its clinical impact. We aimed to determine whether extensive cervical LN dissection is responsible for favourable clinical outcomes in PTC patients with HT and whether the coexistence of HT itself has an independent protective effect regardless of LN status. Design Retrospective cohort study. Patients 1369 patients with PTC who underwent total thyroidectomy with central compartment neck dissection. Measurements Metastatic LN ratio, defined as number of metastatic LNs divided by number of removed LNs, was used to evaluate the extent of LN dissection as well as the status of LN metastasis. Disease-free survival and dynamic risk stratification were compared for clinical outcomes. Results Presence of HT did not lower the risk of cervical LN metastasis (61.6% in patients with HT vs 65.1% in patients without HT, P = .292). Patients with HT had significantly larger numbers of removed LNs than patients without HT (11 vs 8, respectively, P

The link between chronic lymphocytic thyroiditis (CLT) and papillary thyroid carcinoma (PTC) is widely recognized. Considering the strong association between raised antithyroidperoxidase antibody (TPOAb) and CLT, we postulated that the preoperative TPOAb can predict the prognosis of PTC, particularly for recurrence. A total of 2,070 patients who underwent total thyroidectomy for classical type PTC with tumor size ≥1 cm and with available data on preoperative TPOAb and TgAb were enrolled to compare disease-free survival (DFS) according to the presence of preoperative TPOAb, TgAb, and coexistent CLT. Patients with positive preoperative TPOAb had a significantly better DFS compared to patients without positive preoperative TPOAb (hazard ratio (HR) 0.53; 95% confidence interval (CI) 0.30-0.94, p = 0.028) while no difference in DFS was found according to preoperative TgAb status. Positive preoperative TPOAb was an independent prognostic factor for structural persistent/recurrent disease after adjustment for major preoperative risk factors such as age, sex, and tumor size (HR 0.52, 95% CI 0.28-0.99, p = 0.048). Although the coexistence of CLT lowered the risk for structural persistence/recurrence in univariate analysis (HR 0.52, 95% CI 0.31-0.86, p = 0.012), it was not an independent favorable prognostic factor by multivariate analysis (HR 0.65, 95% CI 0.38-1.10, p = 0.106). However, when coexistent CLT was combined with positive preoperative TPOAb, it indicated an independent protective role in structural persistent/recurrent disease (HR 0.39, 95% CI 0.16-0.98, p = 0.045). Our study clearly showed that presence of preoperative TPOAb can be a novel prognostic factor in predicting structural persistence/recurrence of PTC.