Multifocal Micropapillary Thyroid Cancer: A New Indication for Total Thyroidectomy?

Abstract

American Thyroid Association guidelines recommend total thyroidectomy (TT) for thyroid cancers 1 cm or greater. Liberal use of neck sonography has resulted in an increased incidence of papillary cancers detected at earlier stages with approximately half at the micropapillary level and occasionally multifocal. Concerns regarding the safety of routine TT, especially in young patients with favorable cancers, and the clinical significance of detected multifocal micropapillary cancers have been raised. Records of 516 consecutively treated patients with thyroid cancer were reviewed. A subset of 269 cases with well-differentiated papillary thyroid cancer (WDPTC) confined within the capsule of the involved lobe undergoing TT was analyzed. Patients were stratified according to age, tumor size, evidence of ipsilateral multifocality, and presence or absence of contralateral nonpalpable malignancy. Overall contralateral histologic malignancy was demonstrated in 46.4 per cent (125 of 269). The incidence was 34 per cent (30 of 88) of subcentimeter (less than 1 cm) tumors and significantly increased to 52 per cent (95 of 181) in tumors 1 cm or greater ( P = 0.006). This incidence significantly approached 76 per cent (13 of 17) in subcentimeter but multifocal tumors when 45 years or older ( P = 0002). One patient developed permanent hypocalcemia (0.4%). There were no recurrent nerve injuries. The incidence of bilateral cancer was significant in 1-cm or greater WDPTC. Patients with subcentimeter multifocal tumors, when older than 45 years, were even at higher risk for bilateral cancer. Because TT is advocated for patients with WDPTC 1 cm or greater, it should also be considered in those older than 45 years with ipsilateral multifocal micropapillary cancers, because it can be performed safely.