Pituitary Metastases: A Nationwide Study on Current Characteristics with Special Reference to Breast Cancer

Objective To investigate the contemporary presentation of pituitary metastases. Patients Thirty-eight patients diagnosed with pituitary metastases from 1996 to 2018 in Sweden. Methods Pituitary metastases were confirmed by histopathology (n = 27) or considered highly likely according to radiological findings, including rapid tumor progression (n = 11). Medical records were reviewed and sellar images reexamined centrally. Results Breast and lung cancers were the most common primary tumors, in 45% and 21% of patients, respectively. Sixty-seven percent of breast cancers overexpressed human epidermal growth factor receptor 2 (HER2); 53% of pituitary metastases from breast cancers appeared ≥10 years after diagnosis of the primary tumor. At presentation, 71% appeared to have ACTH deficiency, 65% had TSH deficiency, and 26% had diabetes insipidus. Fatigue, nausea/vomiting, loss of appetite, weight loss, myalgia, and/or arthralgia were reported in 47% of patients with morning cortisol <100 nmol/L vs 23% with cortisol ≥200 nmol/L. Sixteen patients had visual field defects, and eight had diplopia. Intrasellar and suprasellar tumor growth was the most frequent finding. Initially, a pituitary adenoma was considered the etiology in 18% of patients. Radiotherapy, pituitary surgery, and chemotherapy were used in 68%, 68%, and 11% of patients, respectively. One and 2 years after diagnosis of pituitary metastases, 50% and 26% of patients were alive. Conclusion Pituitary metastases may be mistaken for pituitary adenomas and can appear late, especially in breast cancer. Breast cancers overexpressing HER2 seem prone to metastasize to the pituitary. Hypocortisolism may be misdiagnosed as cancer-related malaise. An increased awareness of pituitary metastases and undiagnosed pituitary failure can improve management in these patients.