Approximately 66% of patients with medullary thyroid carcinoma do not receive a complete thyroidectomy or central neck lymph-node dissection, despite recommendations in the American Thyroid Guidelines suggesting combining the two procedures.
Previous research has shown that small medullary thyroid cancers—even those less than 1 cm in size—are 40% likely to metastasize to the lymph nodes. The performance of central neck nodal dissection in medullary carcinoma is critical to limiting the risk of such metastases.
Eric J Kuo, MD, department of surgery, UCLA David Geffen School of Medicine, and colleagues conducted a study to measure a potential association between initial neck dissection and the need for reoperation in medullary thyroid carcinoma. The population-based study consisted of 953 patients diagnosed with medullary thyroid carcinoma from 1999 to 2012. Only those who underwent thyroidectomy and had a minimum postoperative follow-up of 2 years (n = 609) were included in the final analysis.
Results were published in JAMA Surgery (online September 27, 2017; doi:10.1001/jamasurg.2017.3555).
Researchers found that despite initial central neck dissection being recommended by American Thyroid Guidelines, only 35.5% of patients (n = 216) underwent central neck dissection at the time of initial thyroidectomy. Among the entire cohort, 16.3% (n = 99) required reoperation after a median time of 6.4 months. After adjusting for multiple confounding factors, researchers found that a leading risk factor for reoperation was the presence of lymph-node metastasis (HR, 3.43; 95% CI, 2.00-5.90).
On the contrary, central and lateral neck dissection performed at the initial operation was found to be protective of the risk of reoperation (HR, 0.53; 95% CI, 0.30-0.93).
Researchers also noted that among the patients who underwent reoperation, 45.5% (n = 45) were disease free at a median follow-up of 7.7 years. Five-year disease-specific mortality for the entire patient population was 13.5% (n = 82).
Authors of the study concluded that while lymph node dissection is guideline-recommended and may decrease recurrence leading to reoperation for patients with medullary thyroid carcinoma, central neck dissection remains vastly underused.
“The low rate of adherence to American Thyroid Association (ATA) guidelines was one of the more puzzling findings of our study,” commented senior author Masha J Livhits, MD, department of surgery, UCLA David Geffen School of Medicine, in a press release (September 29, 2017). Potential contributors to this low rate of adherence, Dr Livhits believes, are lack of awareness of the guidelines and lack of awareness of medullary thyroid carcinoma diagnosis until after the operation.—Zachary Bessette