Whether cancer risk in acromegaly is increased remains controversial. Also, the risk of benign tumors has been little studied.
To investigate the incidence of benign and malignant tumors in acromegaly in a nationwide population-based study.
Adult patients diagnosed with acromegaly between 1987 and 2017 were identified in the Swedish National Patient Registry. The diagnoses of benign and malignant tumors were recorded. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) for neoplasms with 95% confidence intervals (CIs) were calculated using the Swedish general population as reference.
The study included 1296 patients (52% women). Mean (SD) age at diagnosis was 51.6 (14.7) years. Median (range) follow-up time was 11.7 (0-31) years. Overall, 186 malignancies were identified in acromegalic patients compared to 144 expected in the general population (SIR 1.3; 95% CI, 1.1-1.5). The incidence of colorectal and anal cancer (SIR 1.5; 95% CI, 1.0-2.2), and renal and ureteral cancer (SIR 4.0; 95% CI, 2.3-6.5) was increased, whereas the incidence of malignancies of the respiratory system, brain, prostate, and breast was not. Only three cases of thyroid cancer were recorded. Mortality due to malignancies was not increased (SMR 1.1; 95% CI, 0.9-1.4). Incidence of benign tumors was increased more than 2-fold (SIR 2.4; 95% CI, 2.1-2.7).
Patients with acromegaly had an increased risk of both benign and malignant tumors including colorectal and anal cancer, and renal and ureteral cancer. Whether this is associated with acromegaly itself or due to more intensive medical surveillance remains to be shown.

© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society.