Radiation techniques for acromegaly

Radiotherapy (RT) remains an effective treatment in patients with acromegaly refractory to medical and/or surgical interventions, with durable tumor control and biochemical remission; however, there are still concerns about delayed biochemical effect and potential late toxicity of radiation treatment, especially high rates of hypopituitarism. Stereotactic radiotherapy has been developed as a more accurate technique of irradiation with more precise tumour localization and consequently a reduction in the volume of normal tissue, particularly the brain, irradiated to high radiation doses. Radiation can be delivered in a single fraction by stereotactic radiosurgery (SRS) or as fractionated stereotactic radiotherapy (FSRT) in which smaller doses are delivered over 5-6 weeks in 25-30 treatments. A review of the recent literature suggests that pituitary irradiation is an effective treatment for acromegaly. Stereotactic techniques for GH-secreting pituitary tumors are discussed with the aim to define the efficacy and potential adverse effects of each of these techniques

DOES ACROMEGALY REALLY PREDISPOSE TO AN INCREASED PREVALENCE OF GASTROINTESTINAL TUMORS

OBJECTIVE The few published prospective studies suggest a strong association of colonic tumours with acromegaly, but include small numbers of patients. In addition, the upper gastrointestinal tract of these patients has never been prospectively studied. The aim of the present study was to investigate the incidence of gastric and colonic tumours in a large cohort of acromegalic patients. DESIGN Acromegalic patients consecutively admitted to an Endocrinology Department for diagnosis and followup, were submitted to gastroscopy and colonoscopy, to identify those harbouring gastrointestinal tumours. PATIENTS Over a 5-year period, 54 out of 61 patients (78% with active disease) received colonoscopy and 42 out of 61 gastroscopy. No patient had a past history of gastrointestinal malignancy. MEASUREMENTS All polypoid lesions found at colonoscopy and gastroscopy were separately recorded and biopsied. RESULTS No case of gastrointestinal cancer or gastric polyp was discovered. Nineteen patients (35%) had 1-8 colonic polyps, including 5 (9.3%) with adenomas. When compared to patients with a normal colon, those with polyps were significantly older (44.5 +/- 14.2 vs 52.1 +/- 10.9 years, P = 0.047), but the duration of acromegaly (10.8 +/- 8.4 vs 10.9 +/- 7.1 years, P = 0.9) and the number of patients with active disease were similar in both groups. CONCLUSIONS Acromegalic patients do not have an increased incidence of gastric tumours. The observed significant variation in the prevalence of colonic adenomas (9-35%, P = 0.03) and cancer (0-15%, P = 0.017), between our patients and those of the published prospective studies with similar demographic characteristics, suggest that environmental and hereditary factors may be more important than the presence of acromegaly

Assessment of GH reserve before and after successful treatment of adult patients with Cushing's syndrome.

OBJECTIVE: Several studies have demonstrated impaired GH secretion in patients with active Cushing's syndrome (CS). It has been suggested that persistence of GH deficiency, despite treatment of cortisol excess, may delay the recovery of these patients and therefore temporary treatment with GH may have some benefit. However, the time course of restoration of GH secretion after successful treatment of CS has only been investigated in a limited number of mostly paediatric reports. The aim of the present study was the evaluation of GH reserve in adult patients with CS before and after correction of cortisol excess. DESIGN AND PATIENTS: Sixteen patients (12 females, four males) with CS aged 44.7 +/- 5.05 years were recruited. These included seven patients with Cushing's disease, four patients with ectopic ACTH secretion and five patients with adrenal adenoma. All patients were evaluated before any therapeutic intervention. Twelve patients were successfully treated following appropriate surgery and these were further studied. The combined pyridostigmine/GHRH test was used to assess GH reserve in these patients. In a proportion of cases an insulin tolerance test (ITT) was also used. RESULTS: Before any therapeutic intervention, an impaired GH response to PD/GHRH was noted in all patients. Restoration of GH response at 6 months was observed in six patients (50%); at 12 months in two; at 18 months in one patient. Two of the patients with no restoration of GH response at 12 months did not accept further investigation. Only one patient did not achieve an adequate GH response even when tested 30 months following cure of CS. Restoration of GH reserve was more commonly observed in those patients in whom there was recovery of the HPA axis. There was a good correlation between peak GH levels to PD + GHRH and ITT. No statistically significant difference was revealed in IGF-I levels between pre- and post-treatment evaluation. CONCLUSIONS: Adult patients with active Cushing's syndrome demonstrate a profound suppression of stimulated GH secretion. In the majority of these patients the disruption of GH secretion is normalized within a year after successful treatment of endogenous cortisol excess

Megavoltage pituitary irradiation lowers but seldom leads to safe GH levels in acromegaly: a long-term follow-up study

Radiotherapy (RT) has long been used in the treatment of acromegaly, but confusion regarding the definition of biochemical cure has hampered interpretation of previous reports on the outcome of this treatment. In the present study we present additional data using the currently accepted criteria of biochemical cure in a large group of patients followed up by our department. Forty-six acromegalic patients were treated with external beam megavoltage RT and followed up for a mean of 7.6 years (range 2-22 years). Only four patients had had previous surgical treatment by either transsphenoidal or transfrontal routes. Following RT, mean basal GH levels decreased from 30.9 ng/ml (5-96 ng/ml) to 11.5 ng/ml (1-36 ng/ml) at 10 years of follow up with a further fall to 6.1 ng/ml (1-29 ng/ml) in those patients followed up for more than 10 years. As a result, although mean GH levels of less than 5 ng/ml were achieved in 9/28 (30.1%) at 5 years, 6/19 (31.6%) at 10 years, and in 6/11 (54.5%) of those patients followed up for more than 10 years post-RT, only 0/28 (0%), 7/28 (25%), 4/19 (21%) and 1/11 (1%) achieved GH levels of 12.5 ng/ml at 2, 5, 10 and >10 years following RT. Thus, in the whole series only 10/48 (20.8%) patients showed a decrease of GH level to less than 2.5 ng/ml at their latest follow up. Hypopituitarism as a result of RT was only infrequently observed in this series; gonadal deficiency developed in 12 (26.6%) patients, thyrotrophin (TSH) deficiency in 3 (6.6%) and adrenocorticotrophin deficiency in 2 (4.4%). In conclusion, megavoltage RT is an effective treatment for the control of GH hypersecretion in acromegaly, with a continuing lowering effect for several years following RT, but seldom leads to safe GH levels

Evaluation of GH reserve in patients with adrenal incidentalomas and biochemical evidence of subclinical autonomous glucocorticoid hypersecretion.

OBJECTIVE: Although it is well established that overt hypercortisolism in patients with active Cushing's syndrome leads to a profound suppression of stimulated GH secretion, the role of subclinical autonomous glucocorticoid hypersecretion (SAGH), currently detected with increasing frequency in patients with adrenal incidentalomas, on GH secretory reserve has received little attention. The aim of the present study was to evaluate whether SAGH in patients presented with adrenal incidentalomas has a negative effect on GH secretory reserve. DESIGN AND PATIENTS: Sixteen patients with overt Cushing's syndrome (CS) and 36 patients with adrenal incidentalomas were investigated. The latter group was further divided in 23 patients who demonstrated an adequate suppression of cortisol levels (of < 70 nmol/l) following the low-dose dexamethasone suppression test (LDDST) and in 13 patients, who failed to suppress (cortisol levels post-LDDST > 70 nmol/l). The former group was defined as normocortisolaemic (NC) and the latter group as representing patients with SAGH. The combined pyridostigmine + GHRH test (PD + GHRH) was used to assess the GH secretory reserve of these patients. RESULTS: Peak GH levels following PD + GHRH administration were significantly lower in CS patients compared to both the NC and SAGH group of patients with adrenal incidentalomas (2.2 +/- 0.7 vs. 18.9 +/- 2.6 and 21.5 +/- 3.6 microg/l, respectively, P < 0.05); no difference was observed in peak GH responses between the NC and SAGH group of patients. A subnormal GH response (defined as GH(max) < 12.8 microg/l) was observed in all 16 patients with CS. However, only seven NC and three SAGH patients failed to respond adequately. Correlation analysis revealed a negative correlation between peak GH response to PD + GHRH and plasma cortisol concentrations in CS patients (R =-0.6, P = 0.012), while in patients with adrenal incidentalomas such a correlation was absent. Contrary to patients with CS in whom body mass index (BMI) was not correlated to peak GH, a significant negative correlation between peak GH response to PD + GHRH and BMI was disclosed in patients with adrenal incidentalomas (R =-0.49, P = 0.003). In these patients, again contrary to CS patients, a significant negative correlation was also found between peak GH post PD + GHRH and age (R = -0.46, P = 0.002). CONCLUSIONS: In conclusion, our results provide evidence that, contrary to patients with overt CS, SAGH does not affect the GH secretory response to provocative stimulation

Tumors metastatic to the pituitary gland: Case report and literature review

Tumors metastatic to the pituitary gland are an unusual complication of systemic cancer typically seen in elderly patients with diffuse malignant disease. Breast and lung are the commonest sites of the primary tumor, whereas diabetes insipidus is the most frequent symptom at presentation. Their rarity and usually indolent course, as well as the lack of specific clinical and radiological features, impede their differentiation from other more common sellar area lesions, particularly when history of malignancy is absent. Management of these patients may also be very difficult because the prognosis depends on the course of the primary neoplasm. A 68-yr-old man, with no history of malignancy, presented with recent onset of hypopituitarism, mild diabetes insipidus, headaches, left oculomotor nerve palsy, and progressive bilateral deterioration of visual acuity and visual fields. Magnetic resonance imaging revealed a large sellar mass compressing the optic chiasm and invading the left cavernous sinus, whereas a prolactin elevation at 438.6 ng/ml (19.73 nmol/liter) was noted. Decompression of the sellar region was attempted, and pathology disclosed a metastatic hepatocellular carcinoma. On postoperative investigation, primary liver tumor was identified and confirmed by biopsy. The patient improved transiently but died 3 months after diagnosis because of deterioration of the liver disease. The relevant literature is reviewed in light of this unusual case, illustrating the problems in the diagnosis and management of patients with metastasis to the pituitary