O3315: Thyroid Cancer beyond the Sistrunk Procedure: a Retrospective Review

Background: Thyroglossal duct cysts (TDC) are embryological remnants of a failed obliteration of the thyroglossal duct, which forms during the development of the thyroid gland. The incidence of TDC is 7% worldwide and clinically presents in childhood as a neck mass. TDC carcinomas (TDCC) are rare, with a reported incidence of 1-2% of TDCs. The current recommended treatment for TDC is surgical excision, known as a Sistrunk procedure. The Sistrunk has been shown to reduce recurrence rate, but its impact on preventing thyroid cancer remains unclear. Therefore, we aim to elucidate the relationship between Sistrunk and thyroid cancer incidence, which is important for clinical care and risk stratification.

Methods: The analysis was performed using the US Collaborative Network on TriNetX, an aggregated, de-identified platform with 68 Health Care Organizations (HCOs) and over 120 million patients. Three cohorts were defined — those without TDC, those with TDC and a Sistrunk procedure, and those with TDC and without Sistrunk procedure. TDC and thyroid cancer were based on the presence of one or more ICD encounter diagnosis codes for TDC (ICD10CM:Q89.2) or thyroid cancer (ICD10CM:C73). Sistrunk procedure was based on the presence of a CPT code for excision of thyroglossal duct cyst or sinus (CPT60280) or SNOMED code for Sistrunk operation for thyroglossal cyst (SNOMED 274995003). Characteristics of the cohorts (age, gender, and race) were balanced using propensity score matching. Thyroid malignancy was the outcome of interest.

Results: There was a total of 23,484,406 patients in the final cohort who matched inclusion and exclusion criteria. Results demonstrated that patients with TDC, regardless of Sistrunk procedure, had a statistically significant higher risk of thyroid cancer as compared to controls (TDC with Sistrunk vs. control OR=12.20(7.32, 20.34)) (TDC without Sistrunk vs. control OR = 13.17 (9.98,17.39)). The likelihood of developing thyroid cancer among TDC patients with and without Sistrunk was not statistically significant (OR= 1.21 (0.97, 1.50).

Conclusion: TDC themselves rarely develop into carcinoma. However, the relationship between Sistrunk procedures and thyroid malignancy is poorly understood. We demonstrated that TDCs are strongly associated with developing thyroid cancer, regardless of Sistrunk procedure. This suggests that excision procedures fail to mitigate risk, and the association between TDC and thyroid malignancy may be driven by the TDC itself. Therefore, patients with TDC should have increased longitudinal surveillance as part of care management.