Detection and yield of thyroid cancer surveillance in adults with PTEN hamartoma tumour syndrome.

Thyroid cancer surveillance (TCS) with ultrasound (US) is advised for PTEN hamartoma tumour syndrome (PHTS) patients due to increased thyroid cancer (TC) risk. However, data supporting TCS guidelines are scarce. We aimed to assess the detection and yield of annual TCS with US in adult PHTS patients without a TC history and to evaluate the impact of a reduced US interval on the TCS yield. A retrospective cohort study was conducted, including adult PHTS patients and medical record data between 2005 and 2021. The yield from annual TCS was compared with hypothetical biennial and triennial TCS after two initial US with annual interval by counting delayed detection of nodular growth, thyroid adenoma, and TC. During 279 follow-up years, 84 patients (median age 40 years) underwent 349 US. Thyroidectomy was performed in 6/84 (7%) patients, revealing a minimally invasive follicular TC in one patient aged 22 and a thyroid adenoma in two patients aged 21 and 53. Multiple thyroid nodules were diagnosed in 73/84 (87%) patients (median age 36 years). Nodular growth was detected in 9/56 (16%) patients, and its detection would have been delayed in 4-7% US rounds with biennial TCS, and in 2-6% US rounds with triennial TCS. US-based thyroiditis and indeterminate non-malignant lymph nodes were found in 8/74 (11%) and 7/72 (10%) patients, respectively. Following our findings combined with the literature, we propose starting TCS before age 18 and reducing the follow-up frequency after the initial two US from annual to biennial if no suspicious findings are detected.