Evaluating the projected surgical impact of reclassifying noninvasive encapsulated follicular variant of papillary thyroid cancer as noninvasive follicular thyroid neoplasm with papillary-like nuclear features

Background: The reclassification of noninvasive encapsulated follicular variant of papillary thyroid cancer to noninvasive follicular thyroid neoplasm with papillary-like nuclear features will reduce nonefficacious and potentially harmful care. Reclassification is estimated in 18.6% of patients with papillary thyroid carcinoma; we aimed to quantify the implications of this change.

Methods: Pathology reports from April 2006 to April 2016 were reviewed to isolate cases that would have been designated as neoplasm with papillary-like nuclear features. Of the 1,335 cases of papillary thyroid carcinomas, 194 cases (14.5%) met criteria. Cases in which neoplasm with papillary-like nuclear features was found in combination with other thyroid malignancies (n = 25) and cases of prior thyroid lobectomy (n = 5) were excluded. Demographic, pathologic, treatment, and follow-up data were assessed for the remaining 164 potential neoplasm with papillary-like nuclear features cases. Logistic regression analysis was performed to evaluate association between fine-needle aspiration result and index procedure.

Results: Of the 164 patients with tumors who met neoplasm with papillary-like nuclear features criteria, fine-needle aspiration results were nondiagnostic (2%), benign (18%), atypia/follicular lesion of undetermined significance (26%), follicular neoplasm or suspicious for follicular neoplasm (20%), suspicious for malignancy (19%), malignant (6%), and not obtained (9%). Eighty-five (52%) patients underwent total thyroidectomy. A "suspicious for malignancy" fine-needle aspiration result was associated with undergoing total thyroidectomy versus thyroid lobectomy (P = .006). Thyroid lobectomy was the index procedure for 79 patients (48%); of these patients, 54% (n = 43, 3.2% of all patients with papillary thyroid carcinomas) underwent subsequent total thyroidectomy, and 24% received postoperative radioactive iodine treatment. There were no recurrences among the 125 patients with >3 months of follow-up.

Conclusion: The reclassification of noninvasive encapsulated follicular variant of papillary thyroid cancer as neoplasm with papillary-like nuclear features will decrease nonefficacious treatment and reduce costs. However, the impact of this change with regard to extent of surgery was limited to 3.2% of patients with papillary thyroid carcinomas compared with the projected potential impact on 18.6%.