Thyroid lobectomy is sufficient for differentiated thyroid cancer with upgraded risk after surgery

BACKGROUND: It is difficult to reliably distinguish between American Thyroid Association (ATA) low-risk and intermediate-risk differentiated thyroid cancer (DTC) before surgery. Therefore, physicians are faced with a dilemma regarding the necessity and timing of completion total thyroidectomy (CT) after thyroid lobectomy (TL). We evaluated proper surgical methods by analyzing oncologic outcomes of TL in patients with DTC whose risk had been upgraded after surgery. METHODS: We retrospectively reviewed the medical records of 1,702 patients with DTC who underwent TL and ipsilateral central lymph node (LN) dissection between January 2006 and December 2011. The patients were classified into Group A (n=1,159; low risk; ≤5 central LN metastases or the absence of pathologic microscopic capsular invasion) and Group B (n=543; upgraded intermediate risk after surgery; >5 central LN metastases or the presence of pathologic microscopic capsular invasion). We analyzed their clinicopathological characteristics and recurrence-free survival. RESULTS: All 32 patients who experienced recurrence underwent CT. After the first operation, the duration until reoperation in Groups A and B were 8.00±2.74 (range, 3.42–12.17) and 5.10±3.09 (range, 1.25–11.67) years, respectively. There was no significant difference in recurrence rates, disease-related mortality rates, or 10-year recurrence-free survival rates between the two groups. The mean follow-up durations in Groups A and B were 10.22±1.58 and 10.13±1.47 years, respectively. Univariate analysis showed that sex, age, tumor size, multifocality, extrathyroidal extension (ETE), and number of central LN metastases were not associated with recurrence after TL, although the rate of central LN metastases was. Multivariate analysis showed that sex, age, tumor size, multifocality, ETE, central LN metastases, and the number of central LN metastases were not associated with recurrence after TL, although multifocality was. CONCLUSIONS: TL with prophylactic central compartment neck dissection (CCND) is sufficient for patients with DTC whose risk is upgraded after surgery because they have a good prognosis at long-term follow-up. Larger-scale randomized clinical trials are required to confirm our findings.