Cancer Incidence in Patients with Acromegaly: A cohort study and meta-analysis of the literature

Context: Acromegaly has been associated with increased risk of cancer morbidity and mortality, but research findings remain conflicting and population-based data are scarce. We therefore examined whether patients with acromegaly are at higher risk of cancer.

Design: A nationwide cohort study (1978-2010) including 529 acromegaly cases was performed. Incident cancer diagnoses and mortality were compared to national rates estimating standardized incidence ratios (SIRs). A meta-analysis of cancer SIRs from 23 studies (including the present one) was performed.

Results: The cohort study identified 81 cases of cancer after exclusion of cases diagnosed within the first year (SIR 1.1 [95% confidence interval (CI): 0.9-1.4]). SIRs were 1.4 [95% CI: 0.7-2.6] for colorectal cancer, 1.1 [95% CI: 0.5-2.1] for breast cancer, and 1.4 [95% CI: 0.6-2.6] for prostate cancer. While overall mortality was increased in acromegaly (SIR 1.3 [95% CI: 1.1-1.6]), cancer-specific mortality was not. The meta-analysis yielded a SIR of overall cancer of 1.5 [95% CI: 1.2-1.8]. SIRs were elevated for colorectal cancer: 2.6 [95% CI: 1.7-4.0], thyroid cancer: 9.2 [95% CI: 4.2-19.9], breast cancer: 1.6 [1.1-2.3], gastric cancer: 2.0 [95% CI: 1.4-2.9], and urinary tract cancer: 1.5 [95% CI: 1.0-2.3]). In general, cancer SIR was higher in single-center studies and in studies with < 10 cancer cases.

Conclusions: Cancer incidence rates were slightly increased in acromegaly patients in our study and this was supported by the meta-analysis of 23 studies, although it also suggested the presence of selection bias in some earlier studies.