PracticeUpdate: Diabetes

CONFERENCE COVERAGE 20

Thyroid Nodule Location a Predictive Risk Factor for Malignancy Risk of malignancy four times greater for nodules in the upper pole N ew research presented at AACE 2018 has found that thyroid nodule location may be a risk factor for malignancy. Specifically, the risk of malignancy for nodules in the upper pole was four times greater than for nodules in other locations. Although previous research has found a relationship between malignancy and sonographic characteristics – including microcalcifications, hypoechoic nodules, infil- trative margins, increased vascularity, and nodules that are taller than wide. This is the first study that has explored the connection between nodule location and malignancy, according to study author Fan Zhang, MD, PhD, a resident in the Department of Internal Medicine at Brookdale Uni- versity Hospital and Medical Center in Brooklyn, New York. The retrospective, single-center study identified a higher frequency of malignancy in nodules located in the upper pole of the gland (22.2%) compared to the lower pole (4.7%) and middle pole (14.3%). After adjusting for number of thy- roid nodules, participants age, gender, body mass index, and laterality using a multiple logistic regression model, an association between nodule location and malignancy was confirmed. Data were collected prospectively, in 219 individuals with thyroid nodules who had a fine-needle aspiration biopsy between July 2016 to June 2017. Thirty-one individuals with Bethesda I (non-diagnostic) nodules were assigned for observation based on clinical grounds and excluded from analysis. In addition to participant demographics, character- istics of the thyroid nodule were examined on ultrasound. This included laterality of the nodule biopsied (left versus isthmus versus right), polarity (upper versus middle versus lower), microcalcifications, and multi-nodularity. The research team found that nodules were evenly distrib- uted between the right lobe (47.3%) and left lobe (50.5%), with the rest of the nodules located in the isthmus (2.1%). Most nodules (79.3%) were located in the lower pole of the gland as compared to 9.6% in the upper pole and 6.9% in the middle pole. Almost 40% of individuals had multi- ple nodules. Although it is not known why the upper pole poses a greater risk factor for malignancy, the answer may lie in the anatomy of the thyroid, said Dr. Zhang. She noted that veins in the upper region are what she called “more tor- tuous” and as a result they are slower to drain than the lower lobe. Given the high prevalence of thyroid nodules and the higher malignancy identified by this study, location of thyroid nodules may need to be included in ultrasound clas- sification guidelines, Dr. Zhang said. This would enhance the predictive value of malignancy, diagnostic accuracy, and reliability as an indicator to perform fine-needle aspi- ration, she noted. www.practiceupdate.com/c/68806

Nodule Size Not Linked to Risk of Thyroid Cancer Decision for surgical intervention must be individualized and not solely based on nodule size T he risk of thyroid cancer does not change in larger nodules com- pared to smaller ones, according to a study presented at AACE 2018. Researchers found that within a population of veterans the risk of thyroid cancer neither increased nor decreased for nodules ≥ 3 cm compared to smaller nodules. Studies have shown that thyroid nodules are incidentally found in 4% to 10% of the population. According to the National Cancer Institute, while nodules most are benign, there will be an estimated 53,990 new cases of thyroid cancer this year, along with an estimated 2,060 deaths from the disease. Consequently, emphasis is placed on accurately and precisely assessing the risk of nodules being cancerous, while ensuring that the methods used are safe and cost-effective. While thyroid nodules are routinely measured, studies examining the connection between thyroid nodule size and malignancy have had uncertain results. For example, a 2013 study 1 found an increased risk of cancer in nodules > 2 cm compared with those between 1.0–1.9 cm, but no increased risk with nodule size below this. However, the researchers did find that the risk of follicular carcinomas and other rare thyroid malignancies increases as nodules enlarge. In this current study the researchers, led by Ayfer Ekiz, MD, Wright State University Boonshoft School of Medicine in Dayton, evaluated malig- nancy rates in thyroid nodules ≥ 3 cm compared to those < 3 cm, as well as smaller subgroups. For purposes of the study, Dr. Ekiz and her colleagues performed a ret- rospective chart review of 450 patients at the Dayton Veterans Affairs Medical Center. All of the patients underwent fine-needle aspiration (FNA) biopsies between 2000 and 2016. Of 329 patients eligible for the study, 93 were ≥ 3 cm, while 236 were less than 3 cm. Based on FNA biopsy, the prevalence of cancer was 8.6% in the ≥ 3 cm group and 6.4% in the < 3 cm group (P = .23). Dr. Ekiz and her colleagues divided the patients into four subgroups: nod- ules < 2 cm, 2 cm to < 3 cm, 3 cm to 4 cm, and > 4 cm. The prevalence of cancer in these groups was 6.7%, 5.5%, 9.1%, and 7.9%, respectively (P = .32). There were 86 patients who underwent surgery. Based on surgical pathology, the prevalence of cancer in the ≥ 3 cm group was 33.3% compared to 30.4% in the < 3 cm group (P = .78). After dividing those patients into subgroups, the prevalence of cancer was 35.1% in the < 2 cm group, 21.1% in the 2 cm to < 3 cm group, 42.1% in the 3 cm to 4 cm group, and 18.2% in the > 4 cm group (P = .38). “Our study, the first to examine this relationship in the veteran population, found no association between nodule size and malignancy using either FNA or surgical pathology,” Dr. Ekiz and her colleagues observed. “Cur- rent clinical practice is to refer patients with larger nodules for surgical evaluation. Given our findings and prior conflicting results, the decision for surgical intervention must be individualized and not solely based on nodule size.” Reference 1. Kamran SC, Marqusee E, Kim MI, et al. Thyroid nodule size and prediction of cancer. J Clin Endocrinol Metab 2013;98:564-70. www.practiceupdate.com/c/68815

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