Increased Incidence of Malignancy in Patients with Non-Functioning Pituitary Adenoma – a Nationwide Study

Presentation Number: OR21-4
Date of Presentation: April 2nd, 2017

Daniel S Olsson*1, Casper Hammarstrand1, Ing-Liss Bryngelsson2, Anna G Nilsson1, Eva Andersson3, Gudmundur Johannsson1 and Oskar Ragnarsson1
1Department of Endocrinology, Sahlgrenska University Hospital, Gothenburg, Sweden, 2Örebro University Hospital, Örebro, Sweden, 3Sahlgrenska University Hospital, Gothenburg, Sweden


We have recently shown that patients with non-functioning pituitary adenoma (NFPA) have decreased mortality due to malignant tumors (1). The aim of this nationwide study was to investigate the incidence of malignancy in a large and unselected group of patients with NFPA.

Patients diagnosed with NFPA between 1987 and 2011 were identified in National Health Registries in Sweden. The NFPA diagnosis vas validated against medical records in 17% of the patients. All diagnoses of malignancies were collected from the National Swedish Cancer Register between 1987 and 2014. Standardized incidence ratios (SIRs) with 95% confidence intervals (CI) were calculated.

Included in the analysis were 2 795 NFPA patients, 1 502 men and 1 293 women. The mean (±SD) age at diagnosis was 60±15 years for men and 56±18 years for women. Hypopituitarism was reported in 1 523 patients (55%) and diabetes insipidus (DI) in 151 patients (5%). Of 2 795 patients, 1 500 (54%) had been treated with pituitary surgery and 134 (5%) with radiotherapy. Median follow-up time was 8.6 years (range 0-28) with 26 664 patient-years included in the analysis.

In total, 448 malignancies were diagnosed in 386 patients. The expected number of malignancies from the general population was 368, resulting in a SIR of 1.22 (95% CI 1.11-1.33; P<0.0001). The incidence of neoplasm of the brain was markedly increased (SIR 5.83; 95% CI 4.03-8.14; P<0.0001). When analyzing the total incidence of malignancies excluding neoplasms of the brain, the overall SIR was still increased (SIR 1.14; 95% CI 1.03-1.26; P=0.008). The incidences of colorectal cancer (SIR 0.67; 95% CI 0.46-0.93; P=0.013) and breast cancer (SIR 0.59; 95% CI 0.37-0.89; P=0.012) were reduced. When analyzing only patients with hypopituitarism, the incidences of both colorectal and breast cancer were reduced to a similar degree. For prostate cancer the incidence was as expected (SIR 1.12; 95% CI 0.90-1.37; P=0.32). For other types of malignancy, the incidence did not differ from that in the general population.

This nationwide study showed that patients with NFPA despite having reduced mortality from malignant diseases have an increased over-all risk of developing malignancies. Apart from neoplasm of the brain no other specific malignancy type was overrepresented. In fact, the incidence of both colorectal and breast cancer was reduced. To what extent these findings are due to more frequent medical surveillance, genetic predisposition, or endocrine changes remains unknown.


Nothing to Disclose: DSO, CH, ILB, AGN, EA, GJ, OR