Role of radiotherapy in the management of acromegaly

Radiotherapy in acromegaly: Long-term brain parenchymal and vascular magnetic resonance changes

BACKGROUND

Radiation therapy (RT) effectiveness on hormonal reduction is proven in acromegaly; however, collateral long-term effects are still undetermined. This transversal neuroimaging study on a large cohort of acromegalic patients aimed to investigate the rate of parenchymal and vascular changes after RT.

MATERIALS AND METHODS

Thirty-six acromegalic patients underwent RT (RT+) after unsuccessful surgery and were compared to RT- acromegalic patients matched for age, gender, adenoma features, clinical and surgical history. All patients underwent magnetic resonance angiography (MRA) to investigate intracranial artery abnormalities and FLAIR sequence to assess white matter changes according to the Wahlund scale.

RESULTS

RT+ acromegalic patients had a higher rate of controlled disease (29/36 vs. 12/36, P<0.001). RT+ acromegalic patients had MRI/MRA evaluation 15.3±9.6 years after RT. RT+ acromegalic patients had a significantly higher Wahlund score than RT- acromegalic patients (6.03±6.41 vs. 2.53±3.66, P=0.006) due to increased white matter signal abnormalities at the level of the temporal lobes, the basal ganglia (insula) and the infratentorial regions, bilaterally. Among RT+ patients one died because of temporo-polar anaplastic astrocytoma, one suffered from a stroke due to right internal carotid artery occlusion, one presented with cystic degeneration of the temporal poles. Long-dated RT (>10 years before MR evaluation) was associated with a higher rate of RT-related white matter changes (P=0.0004).

CONCLUSIONS

RT seems to have created a cohort of patients with brain parenchymal changes whose clinical and cognitive impact is still unknown. These patients might require a prolonged MRI and MRA follow-up to promptly detect delayed RT-related complications and minimize their clinical consequences.

Octreotide long-acting repeatable for acromegaly

Acromegaly remains a therapeutic challenge for the endocrinologist. Among the available therapeutic options, octreotide long-acting repeatable (Sandostatin(®) LAR(®), Novartis) plays a chief role, both as a primary therapy and as an adjuvant treatment after unsuccessful surgery. A plethora of papers and a meta-analysis have demonstrated its efficacy in: control of clinical picture; achievement of safe growth hormone and normal age-matched IGF-I levels (both factors associated with restoration of normal life expectancy) in 60-70% of patients; control of tumor volume (with real shrinkage in over half of cases); and halt or reversal of most acromegaly-associated comorbidities. Treatment is well tolerated in most patients and can be safely prolonged for many years if required.

Long-term effects of radiotherapy on cardiovascular risk factors in acromegaly

OBJECTIVE

Radiation therapy (RT) is a useful adjuvant tool for acromegalic patients not cured by surgery and/or not responding to pharmacotherapy. However, its specific effects on cardio- and cerebrovascular morbidity are still on debate.

DESIGN

Retrospective analysis of 42 acromegalic patients cured after conventional radiotherapy (CRT, n=31) or radiosurgery by gamma-knife (GKRS, n=11) followed for a median period of 16.5 years (range: 2-40). Totally, 56 patients cured by surgery alone, with similar GH/IGF1 levels and duration of disease remission, served as control group.

METHODS

Changes in cardiovascular risk factors, such as body mass index, glucose metabolism, insulin resistance, blood pressure, and lipid profile (pre-defined primary end point) and occurrence of new major cardio- and cerebrovascular events (secondary end point) during follow-up.

RESULTS

The number of obese, hypertensive, and dyslipidemic subjects increased over time only in patients cured with RT. In contrast, the glucose response to the oral glucose tolerance test and the percentage of subjects with glucose alterations improved only in controls. As expected, the percentage of patients with pituitary failure was deeply higher among RT patients than among controls (86 vs 30%, P<0.0005). Despite these findings, a similar number of RT patients and controls developed major cardio- or cerebrovascular events (4/42 vs 3/56, P: NS). No differences were found between CRT and GKRS subgroups.

CONCLUSIONS

Previous RT seems to be associated with a worse metabolic profile in acromegalic patients studied after a long-term follow-up. Nevertheless, a direct link between RT and cardiovascular events remains to be proven.

Efficacy and tolerability of gamma knife radiosurgery in acromegaly: a 10-year follow-up study

OBJECTIVE

The long-term efficacy and safety of stereotactic radiosurgery by gamma knife (GK) still remain unknown. The aim of the study was to investigate the long-term efficacy and tolerability of GK in acromegalic patients.

DESIGN AND PATIENTS

Retrospective analysis for a median follow-up of 10 years. Thirty-five acromegalic patients from two referral centres in Milan submitted to GK (median margin dose: 20 Gy, median % isodose: 50) between 1995 and 2004.

MAIN OUTCOME MEASURES

GH/IGF-I secretion, anterior pituitary function, radiological imaging and ophthalmological data.

RESULTS

Cure rate improved over time (up to 46% at 10 years), as did the proportion of patients achieving control on somatostatin analogues (from 12.5% at baseline to 50% at 10 years). Normal IGF-I values were observed in 82% of patients at their last visit. No visual impairment, disease recurrence, tumour growth or secondary cerebral tumour occurred. Half of the patients developed one or more new deficiencies, while two patients normalized their prior failures. In particular, new onset of clinical or subclinical hypoadrenalism occurred in 12/30 patients (40%), hypothyroidism in 3/28 (11%), hypogonadism in 2/15 (13%) and GH deficiency in 2/35 (6%). GH value at the time of GK was the best negative predictor of cure and margin dose was the best positive predictor of new hypopituitarism.

CONCLUSIONS

Over a 10-year period after GK radiosurgery, an increasing percentage of patients achieve cure, or adequate control of the disease on pharmacological therapy, at the expense of increasing novel pituitary deficiencies.

Effects of lanreotide Autogel on growth hormone, insulinlike growth factor 1, and tumor size in acromegaly: a 1-year prospective multicenter study

OBJECTIVE

To evaluate the safety and effectiveness of lanreotide Autogel on growth hormone and insulinlike growth factor 1 (IGF-1) concentrations and tumor size in patients with acromegaly.

METHODS

Between September 2004 and March 2006, patients with active acromegaly who had not previously been treated with somatostatin analogues or received irradiation were enrolled in a 1-year, prospective, open, multicenter study. Lanreotide Autogel was injected subcutaneously starting with 90 mg every 4 weeks for 2 cycles and then individually titrated, aiming for safe growth hormone concentrations (<2.5 ng/mL) and normal age-matched IGF-1 concentrations. Tumor shrinkage, clinical score, pituitary function, and safety parameters were evaluated.

RESULTS

Twenty-seven patients (15 women, 12 men) were enrolled. One patient withdrew because of treatment intolerance, and 5 proceeded to neurosurgery 6 months into the study. Lanreotide Autogel was the primary treatment in 19 patients (4 with microadenoma, 15 with macroadenoma) and the adjuvant treatment in 8 patients in whom it followed a previous unsuccessful neurosurgery. In the 26 patients, safe growth hormone values were achieved in 11 (42%), normal IGF-1 values in 14 (54%), and both targets were achieved in 10 (38%). Tumors shrank in 16 of the 22 patients (73%) in whom tumor shrinkage could be evaluated. The maximal vertical diameter of the tumor decreased by a mean of 24% (range, 0% to 50%), from 14.4 +/- 8.4 mm to 10.4 +/- 7 mm, and tumor volume decreased by a mean of 44% (range, 0% to 76%), from 2536 mm3 (range, 115-7737 mm(3)) to 1461 mm(3) (range, 63-6217 mm(3)) (both P<.015). Symptom scores and lipid levels significantly improved. In the 26 patients, glucose metabolism deteriorated in 3 (12%) and improved in 4 (15%). New biliary alterations appeared in 26%. Pituitary function and safety parameters did not change.

CONCLUSIONS

Lanreotide Autogel treatment, titrated for optimal hormonal control, effectively controls IGF-1 and growth hormone levels, shrinks tumors, reduces acromegalic symptoms, and is well tolerated.

An audit of treatment outcome in acromegalic patients attending our center at Bergamo, Italy

BACKGROUND

Acromegaly is a chronic disease impacting on morbidity and mortality. Increased mortality is reverted after the achievement of hormonal targets. The relative role of treatment options is still matter of debate.

METHODS

A retrospective chart review was performed on all the acromegalic patients attending our center along the last 20 years.

RESULTS

Data about 159 patients (83 F) were retrieved and analyzed: 18% had been lost to follow-up, while follow-up was >5 years in 79%. Growth hormone (GH) at diagnosis was 24 microg/L (median, range 3-239). Pituitary MRI showed a macro-, micro-adenoma or no lesion in 73.6, 22.9, and 3.5%, respectively. Hyperprolactinemia (hyperPRL) was present in 20.8%. Ninety-six and 29 patients had been treated by neurosurgery (NS) and irradiated (RT), respectively. Drugs had been employed in 149 patients (in 58 as the only treatment). At the last evaluation, 22% of patients were cured (hypopituitarism and GH deficiency in 6.3%), 37.1% were controlled by ongoing pharmacological treatment, 22.6% had discordant GH and Insulin-like growth factor I (IGF-I) values, and 18.2% had still active disease (median follow-up in this last group was 9 months). By evaluating the outcome with a multimodal approach, safe GH and normal IGF-I had been achieved in 78 and 63.5% of the whole series, 80.5 and 59.7% in patients submitted to NS (and adjuvantly treated with drugs), 95.8 and 91.7% in those submitted to NS + RT (and drugs as well), 70.2 and 55.2% in those treated only with drugs (increased to 82.2 and 60.9% if considering only patients treated with modern long-acting drugs). Hypopituitarism had occurred in 25, 66.6, and 13.8% in the three groups, respectively. At multivariate analysis, previous RT and NS were significant positive predictors of cure, whereas previous NS, follow-up, and year of diagnosis were significant positive predictors of control. Diabetes was a negative predictor both of cure and control. Sex, age, baseline GH levels, hyperPRL, tumor size, extrasellar extension, and invasiveness were not independent predictors of either cure or control.

CONCLUSION

This series seems to indicate that a multimodal approach can achieve control of disease in most patients.

Nanomedicines in the treatment of acromegaly: focus on pegvisomant

This article examines the role of pegvisomant in the treatment of acromegaly. This syndrome, caused by excessive growth hormone (GH) secretion by a pituitary adenoma, is associated with a doubled mortality rate and poor quality of life. Pituitary microsurgery has long been the first choice of treatment since it cures many patients, especially those with localized tumors. Adjuvant irradiation was given if insulin-like growth factor-I (IGF-I) or GH did not normalize. The introduction of long-acting slow- release somatostatin analogs was a breakthrough for adjuvant treatment, although not always effective. Rather, targeting excessive GH production, muting the GH signal at its receptor, was a totally different approach. The development of GH antagonists (by mutation ofglycine at position 120) and other modifications to enhance receptor binding, and subsequent pegylation of the molecule led to the development of B2036. After pegylation of B2036 at 5 positions the distribution volume is restricted and its serum half-life considerably increased. In short-term clinical studies performed in selected, mostly pretreated, acromegalic patients, IGF-I normalized in the majority of cases. Combination therapy with long-acting somatostatin analogs and weekly rather than daily pegvisomant injections appears to be successful in one clinical study and might limit the high cost of pegvisomant. Long-term efficacy and safety has to be demonstrated. The drug does not cross the blood-brain barrier, and whether it distributes freely into the extracellular space of other organs than the liver has not been investigated, which might have implications for persistent local IGF-I production under unrestrained GH concentrations.