Acromegaly and thyroid cancer: analysis of evolution in a series of patients.

Background: Acromegaly is associated with higher morbidity and mortality mainly due to cardiovascular disease. Data on the incidence and evolution of thyroid cancer in acromegaly are controversial. Our objective was to describe the characteristics of a group of acromegalic patients with differentiated thyroid carcinoma (DTC) and analyze their evolution.

Methods: This is a retrospective multicenter study of 24 acromegalic patients with DTC. The AJCC Staging System 8th Edition was used for TNM staging, and the initial risk of recurrence (RR), initial response and response at the end of follow-up (RFU) were defined according to the 2015 ATA Guidelines. As a control group, 92 patients with DTC without acromegaly were randomly included. Statistical analyses were done using SPSS Statistics 20.0.

Results: Median age of patients at diagnosis of acromegaly was 49.5 years (range 12-69). The median delay in diagnosis of acromegaly was 3 years (range 0.5-23). Mean baseline IGF-1 level was 2.9 ± 1.1 ULN. Median age at DTC diagnosis was 51.5 years (18-69). At the moment of diagnosis of DTC, 58.3% of the patients had active acromegaly. Median time from DTC diagnosis to acromegaly control was 1.25 years (0.5-7). Mean DTC tumor diameter of the biggest lesion was 14.6 ± 9.2 mm, being multifocal in 37.5%. All tumors were papillary carcinomas, two cases being of an aggressive variety. Lymph node dissection was performed in 8 out of 24 patients and 62.5% had metastases. Only one patient had distant metastases. Radioiodine ablation was given to 87.5% of patients. Nineteen patients (79%) were stage I, four (17%) stage II and one (4%) stage IVb. Initial RR was low in 87% (21/24), intermediate in 9% (2/24) and high in 4% (1/24) patient. RFU was: 83% (19/23) patients with no evidence of disease, 9% (2/23) with indeterminate response, 4% (1/23) with biochemical incomplete response and 4% (1/23) with structural incomplete response, at a median time of FU of 36.5 months. When comparing RFU between acromegalics and controls no statistically significant differences were found.

Conclusions: Patients with acromegaly and DTC mostly had a low initial RR. When compared with the control group, we found that DTC patients with acromegaly did not have a worse evolution.