Endocrine Abstracts

Objective: Thyroid cancer (TC) screening in acromegaly is a controversial topic. The Endocrine Society opposes routine TC screening in acromegaly patients without a palpable nodule, and the American Thyroid Association does not consider acromegaly to be a high-risk condition for developing TC. However, acromegaly is associated with an increased risk of TC, and some centers opt for thyroid ultrasound screening even in the absence of palpable thyroid nodules. Being one of the supporters of this strategy, we aimed to present the characteristics of our acromegaly patients with a diagnosis of differentiated TC.

Methods: This was a single-center retrospective cohort study. Among our registry of 395 adult acromegaly patients diagnosed between 1998 to 2022, thirty-one (17 female, 14 male) with a histopathological diagnosis of differentiated TC were evaluated.

Results: The prevalence of differentiated TC in our acromegaly cohort was 7.8%, with a slight female predominance (55%). The mean age (±standard deviation) at the onset of acromegaly symptoms and at acromegaly diagnosis were 38.3±12.1 and 41.8±11.4 years, respectively. The mean time between the two occasions was 3.1±4.2 years. The mean age at TC diagnosis was 47.5±10.5 years. The mean time since acromegaly diagnosis to TC was 5.7±6.8 years. Three patients were diagnosed with TC within the two years prior to being diagnosed with acromegaly, three were diagnosed within a year of being diagnosed with acromegaly, and seven were diagnosed >10 years after being diagnosed with acromegaly. None of the patients had consistently normal IGF-I levels until TC diagnosis. Twenty patients (64.5%) had multiple fine needle aspiration biopsies until being diagnosed with TC. Except for one patient, all were treated with total thyroidectomy; the remaining patient underwent hemithyroidectomy. The mean tumor size was 1.3±1.2 cm, ranging between 2 mm to 5 cm. The most common TC subtype was papillary TC (29, 93.5%). Fifteen patients had multicentric, while ten had bilateral TCs. Cervical lymph nodes were involved in three patients. Vascular invasion and positive surgical margins were identified in three and two patients, respectively. Fifteen patients received radioactive iodine treatment, with a median dose of 100 mCi (range: 50-150 mCi). In four patients, there was another primary malignant neoplasm in addition to TC. There was no TC-related death.

Conclusions: Papillary TC is common in acromegaly patients. While routine thyroid nodule screening has the disadvantage of increasing the risk of overdiagnosis, thyroid ultrasound monitoring would be beneficial, particularly in patients with persistently elevated IGF-I levels.