Endocrine Abstracts

Background: Acromegaly is a rare disorder caused by hypersecretion of growth-hormone (GH) and insulin-like growth factor (IGF-1), the underlying lesion being most frequently a pituitary adenoma. This disease is associated with a higher risk of malignancy. We describe the clinical and biochemical particularities in a series of patients with acromegaly and papillary thyroid carcinoma (PTC).

Case study: Out of 311 acromegalic patients, five cases that associated subsequent PTC were included, resulting in a prevalence of 1.6%. Acromegaly diagnosis was sustained by clinical characteristics, hormonal assays and imaging data. The median age at diagnosis was 42 years with only female patients. One patient had GH and prolactin co-secretion. Transsphenoidal intervention was performed, with postoperative tumor remnant in all cases requiring subsequent medical treatment. Two patients also underwent Gamma knife radiosurgery. Following multimodal treatment, one patient was cured and four had controlled disease. Thyroid cancer was diagnosed at a median of 7.5 years after the diagnosis of acromegaly. All cases presented with the papillary variant. At the time of the cancer diagnosis, 2 out of 5 patients had controlled acromegaly. All five underwent total thyroidectomy and three of them received radioactive iodine. The histopathological analysis revealed four papillary thyroid microcarcinomas (PTMC). One patient had a focus of sclerosing subtype of PTC of over 10 mm, lymph node metastases, and extrathyroidal extension – this patient had co-secretion of prolactin and was the only case with poor oncological outcome. The other patients were cured.

Conclusions: Several studies indicate that a prolonged excess of IGF-1 levels has proliferative and anti-apoptotic effects on follicular thyroid cells, with a prevalence of thyroid cancer in acromegaly of 1.2-10.6% [1]. In our series, all patients were diagnosed with PTC after prolonged and persistent high levels of IGF-1 due to uncontrolled disease. Furthermore, prolactin has a potential tumorigenic role on thyroid follicles [2], the patient with GH and prolactin co-secretion being the one with an aggressive evolution of the PTC. Four patients had PTMC which is acknowledged as a very-low risk neoplasm. In conclusion, although at this point thyroid malignancies are not considered more aggressive in acromegalic patients, periodic thyroid examination is useful in identifying complications in earlier stages.

References: [1] M. Heidarpour et al, “Acromegaly and papillary thyroid carcinoma: A case series,” J Res Med Sci, vol. 24, p. 81, 2019.

[2] A. A. Tam et al, “Differentiated thyroid cancer in patients with prolactinoma,” Turk J Med Sci, p. 6.