Pituitary adenomas in northern Sweden: a study on therapy choices and the risk of second primary tumours.

OBJECTIVES

To present the incidence of pituitary adenomas in northern Sweden and to determine whether the incidence of second primary tumours differs from the incidence in the general population or might be related to radiotherapy.

DESIGN

A retrospective register study.

PATIENTS

A total of 546 patients with pituitary adenomas were identified in the Cancer Registry of northern Sweden between 1958 and 2004. Only patients with histopathological verification and/or endocrine activity of the adenoma and more than 12 months of follow-up were included, resulting in 376 patients in the study.

MEASUREMENTS

The number of patients receiving surgery and/or radiotherapy and presenting second primary tumours were registered. Standard incidence ratios (SIRs) between the observed and the expected incidence of second primary tumours were calculated.

RESULTS

The total number of person-years at risk for a second primary tumour was 4730. Fifty-four out of 376 (14%) patients had 63 second primary tumours. Forty patients had second primary tumours diagnosed more than 12 months after diagnosis of the pituitary adenoma (expected 42.6, SIR 0.94, 95% CI 0.67-1.28). A significantly increased incidence of second primary tumours was seen in 42 men with GH-secreting adenomas. Ten second tumours were found (expected 4.55, SIR 2.20, 95% CI 1.05-4.04). A total of 261 patients received radiotherapy and 31 second primary tumours occurred after radiotherapy (expected 32.9, SIR 0.94, 95% CI 0.64-1.34). Three second primary intracranial tumours appeared within the irradiation volume (expected 0.85, SIR 3.51, 95% CI 0.71-10.36).

CONCLUSIONS

No significant increase was found in the incidence of second primary tumours in general in patients with pituitary adenomas. An increased incidence of second primary tumours was seen in men with GH-secreting adenomas.