MON-510 Patients with Large Multinodular Goiters Operated for Presumed Benign - Large or Growing Thyroid Nodules, Have a High Likelihood of Significant Synchronous Thyroid Cancers

Introduction: Despite the current state of evidence suggesting that thyroid nodules’ size should not be the sole criterion for the decision to undergo thyroidectomy, many patients are still operated for large, or growing nodules. In order to ascertain whether this is a justifiable approach, we performed the present study. Methods/ Subjects: We reviewed the data from two prospectively collected databases of patients undergoing thyroid surgery in two tertiary referral centers, one in the USA (A) and the other one in Greece (B) over 14 consecutive years. We collected data on the preoperative surgical indication, FNA cytology and surgical pathology. We included subjects with multinodular goiters, operated solely for large or growing thyroid nodules, who did not have any known or presumed thyroid cancer, or indications of high risk for malignancy (FNA suspicious for thyroid cancer, follicular neoplasm, suspicious for follicular neoplasm, FLUS/AUS, cellular specimen), family history of thyroid cancer or prior neck radiation exposure. Results: We reviewed 5523 consecutive cases of thyroid surgery (A:2711, B:2812). After excluding n=3059 subjects, we included n=2464 subjects in the present analysis. Overall 535 thyroid cancers were identified (21.7%): 349 (65.2%) were microcarcinomas (<1cm), 161 (30.0%) were macrocarcinomas (≥1cm) and 25 of undetermined size. The histology was consistent with papillary cancer (PTC) n=500, follicular cancer (FTC) n=14, Hurthle cell cancer (HCC) n=9, medullary cancer (MTC) n=4, thyroid lymphoma n=1 and mixed histology cancers n=4. In n=68 (2.75%) cases, a thyroid cancer was found in the large or growing thyroid nodule, which was the original indication for surgery. The cancers were multifocal in n=165 subjects; there was extrathyroidal extension in n=61, capsular invasion was present in n=80, lymph node involvement in n=35 and bone metastasis in n=2 subjects. Conclusions: Although the likelihood of identifying a clinically relevant thyroid cancer in a large or growing nodule, in the absence of risk enhancing features, is low; the risk of synchronous, clinically important, thyroid cancers is high in patients with large multinodular goiters. Therefore, more precise screening strategies are urgently needed to identify the patients, who would clearly benefit from thyroid surgery and protect those who do not need to be operated on.