Frequency of High Risk Characteristics Requiring Total Thyroidectomy for 1-4 cm Well Differentiated Thyroid Cancer.

Background: The extent of thyroidectomy for low-risk well-differentiated thyroid cancer (WDTC) remains controversial. Historically, total thyroidectomy (TT) has been recommended for WDTC >= 1 cm in size. However, recent National Comprehensive Cancer Network and American Thyroid Association guidelines recognize unilateral thyroid lobectomy as a viable alternative for 1-4 cm cancers due to their otherwise favorable prognosis, with TT remaining the preferred option for tumors with unfavorable pathological characteristics. This study sought to determine how often a completion TT would be recommended based on these guidelines if lobectomy was initially performed in patients with 1-4 cm WDTC without preoperatively known risk factors. Methods: Patients who underwent thyroidectomy for 1-4 cm WDTC (January 2000 to January 2010) were retrospectively reviewed. Patients with preoperatively known high-risk characteristics, including gross extrathyroidal extension (ETE) on preoperative imaging, clinically apparent lymph node metastases, distant metastases, history of radiation, and positive family history, were excluded. The pathology specimens from the cancer-containing lobe were evaluated for features that would lead to a recommendation for TT based on current guidelines, including aggressive histology, vascular invasion, microscopic ETE, positive margins, and any positive lymph nodes within the specimen. Results: Of 1000 consecutive patients operated for WDTC, 287 would have been eligible for lobectomy as the initial operation. The mean age in this cohort was 45 years, and 80% were women. Aggressive tall-cell variant histology was found in one patient (0.5%), angio-invasion in 34 (12%), ETE in 48 (17%), positive margins in 51 (18%), and positive lymph nodes in 49 (18%) patients. Completion TT would have been recommended in 122/287 (43%) patients. Even in those with 1-2 cm cancers, completion TT would have been recommended in 52/143 (36%) patients. Conclusions: Nearly half of the patients with 1-4 cm WDTC who are eligible for lobectomy under current guidelines would require completion TT based on pathological characteristics of the initial lobe. Surgeons, endocrinologists, and patients need to balance the relative benefits, risks, and costs of initial TT versus the possible need for reoperative completion TT.