Beta human chorionic gonadotropin (beta-hCG) expression in pituitary adenomas: relationship to endocrine function and tumour recurrence

Abstract

The beta subunit of human chorionic gonadotropin (beta-hCG) is a marker of malignancies. Recent studies have also reported its expression in pituitary adenomas, although its significance is unclear. In this retrospective study, the authors quantitatively investigated the immunohistochemical expression of beta-hCG in 123 patients undergoing surgery for pituitary adenomas and explored its relationship to the rest of the endocrine function, tumour recurrence and Ki-67 nuclear labelling. Based on the endocrine profile and immunohistochemistry, the pituitary adenomas were grouped into non-functioning (NFPA; N = 78) and functioning pituitary adenomas (N = 45). The latter included, 20 growth hormone (GH), 12 prolactin (PRL), 8 adreno-corticotrophin hormone (ACTH) and 5 mixed GH-PRL-producing adenomas. Ninety-three (76%) tumours were classified as primary and 30 (24%) tumours classified as recurrent adenomas. Immunohistochemically, 107 (87%) of pituitary adenomas expressed beta-hCG, which was more common in NFPA (91%) than functioning pituitary adenomas (80%). beta-hCG expression was not different between primary (86%) and recurrent pituitary adenomas (90%) and it was also not related to raised Ki-67 labelling. But, Ki-67 labelling was raised in recurrent pituitary adenomas (33%), compared to primary pituitary adenomas (11%). Although, beta-hCG is expressed in the majority of pituitary adenomas, more especially in NFPA, it is un-related to the risk of tumour recurrence or cellular proliferation as measured by Ki-67 nuclear labelling. The high incidence of beta-hCG expression in pituitary adenomas may provide a target for specific beta-hCG-directed tumour therapies in the future.