Prolactin-Secreting Pituitary Adenomas: Epidemiology and Natural History

Abstract

Prolactinomas are the most common functioning pituitary adenoma and may arise sporadically or present in the context of genetic syndromes (multiple endocrine neoplasia type 1 [MEN-1], familial isolated pituitary adenomas [FIPA]). Their prevalence and incidence have increased in recent years, due to improved awareness and diagnostic methods, and are estimated at about 50 per 105 and 2 per 105 persons, respectively. Prolactinomas are rare in children and adolescents, and little is known about their epidemiology in the elderly. Prolactinomas display clear sex differences in terms of size and age at diagnosis, with a greater proportion of macroadenomas in men, who are usually diagnosed at an older age compared to women. There may also be an effect of menopause on tumor size. Information about the natural history of prolactinomas comes from older studies conducted in women, but they seem to have limited growth potential in this population. Despite the elevated levels of estrogen, pregnancy does not appear to promote tumor growth in most patients. Prolactinomas may be more aggressive in patients with MEN-1 and FIPA, although recently published data suggest that their clinical behavior in MEN-1 may actually be similar to that of sporadic prolactinomas.