Pituitary tumors in the elderly

The proportion of elderly subjects is growing in Western countries and, as a consequence, several diseases are now recognized with increasing frequency in the older segment of the population. Pituitary tumors are no exception to the rule. However, the presentation, diagnosis and management of pituitary tumors in the elderly, defined as patients older than 65 or 70 years depending on the different authors, have received little attention in the literature, probably because of the difficulty in collecting large series of elderly patients with adequate follow-up. In this issue of European Journal of Endocrinology, Turner and coworkers (1) report on a series of consecutive patients aged over 65 years seen at an Endocrinology Department over the last 20 years. All types of pituitary lesion are included, but pituitary adenomas were by far the commonest. Since the study population was recruited from an Endocrinology Department, it is very likely that a referral bias played a role in the frequency of the different types of pituitary tumors, because patients with meningioma of the sellar region, suprasellar craniopharyngioma or intracavernous aneurysm of the carotid artery are usually referred directly to a Neurosurgical Department. Notwithstanding, the paper raises some interesting questions. Is the incidence of pituitary adenomas in the elderly rising? A populationbased study reported a significant increase in incidence in 1970–1989 compared with 1950–1969, but subjects aged over 65 years showed an opposite trend (2). These data were interpreted as reflecting an improved endocrinological and neuroradiological diagnostic capacity that also led to an earlier discovery of pituitary tumors (2). In another epidemiological study performed in Japan and covering the period from 1989 to 1995 (3), the age-adjusted incidence of pituitary adenomas in people more than 70 years old was 2.36 per 100 000, not significantly different from that occurring in people less than 70 years old (1.91 per 100 000). However, there was a sex-related difference in elderly people, since men showed an increase and women a decrease in the age-adjusted incidence of pituitary adenomas. The data of Turner and coworkers, showing an increase in the number of elderly patients diagnosed in the period 1991–1995 in comparison with the period 1981– 1985 (1), apparently seem to confirm the results of the Japanese study. If this trend is confirmed in future epidemiological studies, there are two likely explanations: on the one hand the already mentioned rising proportion of elderly subjects, and on the other the higher incidence in elderly subjects of medical conditions, such as cerebrovascular disease or dementia, that are always more frequently investigated by neuroimaging techniques. If the latter proves correct, the percentage of the so-called ‘pituitary incidentaloma’ should increase specifically in this age group. Is the frequency of the various subtypes of pituitary adenomas in the elderly different from that in the other age groups? The answer is probably yes, but there is a surprising absence of specific epidemiological data on this point. Even the study of Turner and coworkers fails to provide this information, although it could have been examined by comparing the percentage of the different adenoma types in the elderly with that observed in the rest of the patient population seen at the local Endocrine Clinic during the same period. The comparison with autopsy studies is not convincing. It is well known that the frequency of pituitary adenomas found in unselected autopsies is very high, approaching 25% in some series (4), in sharp contrast to the low incidence of clinically relevant tumors. It is, thus, highly debatable whether the pathogenesis of both conditions is similar. Notwithstanding, clinical series of pituitary adenomas in the elderly (1, 5, 6) reveal a higher frequency of nonfunctioning adenomas and a marked underrepresentation of hypersecreting tumors, especially prolactinomas. The latter is not surprising, since signs of prolactin hypersecretion in elderly subjects are not relevant and, usually, only large macroprolactinomas are diagnosed in this age group because of the symptoms of mass effect. Despite several refinements in hormonal and neuroradiological tools, there is still a delay of years between the onset of specific symptoms and the diagnosis of pituitary adenomas. Several factors contribute to make misdiagnosis of pituitary tumors more likely in elderly people. Hypogonadism is one of the earliest symptom in nonfunctioning adenomas, but its presence in postmenopausal women is clinically silent, whereas in the male it is often ascribed to misconception about the physiological decline of sexual function with increasing age. Other symptoms of pituitary hypofunction, such as those due to hypothyroidism and hypoadrenalism, may not be so apparent in the elderly; moreover, the interpretation of endocrine and biochemical tests may not be typical of that found in a younger population (7). European Journal of Endocrinology (1999) 140 378–380 ISSN 0804-4643