Outcome of radiotherapy for acromegaly using normalization of insulin-like growth factor I to define cure

Factors Associated with and Temporal Trends in the Use of Radiation Therapy for the Treatment of Pituitary Adenoma in the National Cancer Database

Objective  Radiation therapy represents an uncommon but important component of treatment plans for some pituitary adenomas (PAs). Although radiation therapy has been used to treat pituitary adenomas for over a century, general trends in the usage of radiation therapy for this purpose have not been reviewed. Additionally, there are few large studies evaluating how radiation therapy is used for the treatment of these benign tumors. Investigating these trends and identifying any variations in radiation therapy utilization would help to better inform treatment decisions and improve patient outcomes. Design  Present study is a retrospective analysis of cases using the National Cancer Database. Setting  The research was organized at a tertiary academic medical center. Participants  Patients were diagnosed with pituitary adenoma between 2004 and 2014 within the National Cancer Database (NCDB). Methods  Temporal trends in the usage of radiation therapy to treat pituitary adenoma were analyzed through a retrospective analysis of 77,142 pituitary adenoma cases from the NCDB between 2004 and 2014. Univariate and multivariate analyses were to examine the relationship between patient, tumor, and treatment factors, and the incorporation of radiation therapy into the treatment of pituitary adenomas. We adjusted for potential confounders such as age, sex, race, comorbidity score, facility type, and year of diagnosis. Results  A total of 77,142 patients met inclusion criteria. Inclusion of radiation therapy in pituitary adenoma treatment was 8.0% in 2004 and steadily declined to a low of 3.1% in 2014. Overall, patients were less likely to receive radiation for their pituitary adenoma over time ( p  < 0.001). Similarly, patients were found to be less likely to receive any type of treatment for PA over time ( p  < 0.001). Multivariable evaluation found patients who were female, between 54 and 64 years of age, or treated at either a Comprehensive Community Cancer Program or an Integrated Network Cancer Program were more likely to receive radiation as part of their pituitary adenoma treatment ( p  < 0.001, odds ratio [OR] = 2.01, confidence interval [CI]: 1.54-2.63; p  < 0.001, OR = 1.84, CI: 1.38-2.44, respectively). Patients were less likely to receive radiation for their PA if they were African American ( p  < 0.001, OR = 0.81, CI: 0.72-0.91). Logistic regression also identified a progressive increase in the likelihood of receiving radiation after a PA diagnosis with increasing tumor size starting with microscopic tumors, peaking at 4 to 5 cm ( p  < 0.001; OR = 15.57; CI: 12.20-19.87). Conclusion  In this sample of pituitary adenoma patients treated at NCDB institutions between 2004 and 2014, we found a steady decline in the incorporation of radiation therapy in treatment, as well as in the use of any type of intervention for PA treatment, suggesting a rise in noninterventional observation of PA.

Efficacy and safety of fractionated conformal radiation therapy in acromegaly: a long-term follow-up study

BACKGROUND AND PURPOSE

Conformal, fractionated radiation therapy (XRT) is variably used as a treatment alternative for active acromegaly patients, usually, after failed pituitary surgery. Our objective was to evaluate the long-term efficacy and safety of XRT using strict criteria of biochemical control.

SETTING, DESIGN, PATIENTS, AND METHODS

Retrospective cohort study of 94 patients (73 women, mean age at radiation 53.16 ± 12.9 years) attending a specialized multidisciplinary clinic between 1998 and 2014 with a mean duration of follow-up of 12.9 ± 7.3 years.

RESULTS

A basal growth hormone < 1 ng/mL and an IGF-1 < 1.2 × the upper limit of normal was achieved by 41% and 50.8%, respectively, at 5 years of follow-up, and by 44% and 66%, respectively, 10 years after XRT. Median tumor volume decreased significantly from 904 mm³ at baseline to 424 mm³ upon last follow-up (p = 0.01). The prevalence of central hypogonadism, central hypocortisolism, and central hypothyroidism increased from 18%, 35%, and 35% at baseline, to 38%, 53%, and 64%, respectively, after 10 years of follow-up. One patient was diagnosed with a meningioma and another one developed optic neuritis. No cerebrovascular events were recorded, and all patients are currently alive.

CONCLUSION

XRT is an effective and reasonably safe means of controlling acromegalic activity. Its main disadvantages are the time required to achieve biochemical control and the development of anterior pituitary hormone deficiencies.

The Role of Radiotherapy in Acromegaly

Radiotherapy has, historically, played a central role in the management of acromegaly, and the last 30 years have seen substantial improvements in the technology used in the delivery of radiation therapy. More recently, the introduction of highly targeted radiotherapy, or 'radiosurgery', has further increased the therapeutic options available in the management of secretory pituitary tumors. Despite these developments, improvements in primary surgical outcomes, an increase in the range and effectiveness of medical therapy options, and long-term safety concerns have combined to dictate that, although still deployed in selected cases, the use of radiotherapy in the management of acromegaly has declined steadily over the past 2 decades. In this article, we review some of the main studies that have documented the efficacy of pituitary radiotherapy on growth hormone hypersecretion and summarize the data around its potential deleterious effects, including hypopituitarism, cranial nerve damage, and the development of radiation-related intracerebral tumors. We also give practical recommendations to guide its future use in patients with acromegaly, generally, as a third-line intervention after neurosurgical intervention in combination with various medical therapy options.

Clinical experiences and success rates of acromegaly treatment: the single center results of 62 patients

BACKGROUND

This study aimed to report the clinical and outcome data from a large cohort of patients diagnosed with acromegaly and treated at our institution over a 20-year period.

METHODS

Sixty-two acromegaly patients (32 women and 30 men) treated and monitored at the endocrinology polyclinic between 1984 and 2013 were enrolled in this retrospective study. Clinical features and patients' treatment outcomes were evaluated. A level of growth hormone (GH) of <2.5 ng/ml was considered as the criterion for remission, and the normal insulin-like growth factor (IGF) range was based on gender and age.

RESULTS

The mean age at the time of diagnosis was 38.8 ± 1.4 years, the time to diagnosis was 4.5 ± 0.3 years, and the follow-up duration was 7.3 ± 0.8 years. Among patients' symptoms, growth in hands and feet and typical facial dysmorphism were the most prominent (92%). The number of patients with diabetes mellitus, hypertension and hyperprolactinemia were 22 (35%), 13 (21%) and 13 (21%), respectively. Microadenomas and macroadenomas were found in eight and 54 patients, respectively. A significant correlation was found between the initial tumor diameters and GH levels (p = 0.002). The mean GH and IGF-1 levels were 39.18 ± 6.1 ng/ml and 993.5 ± 79 ng/ml, respectively. Visual field defect was found in 16 patients (32%). Thirty-one patients were treated by transsphenoidal surgery. Four of these were cured, 10 patients developed postoperative anterior pituitary hormone deficiency, and one patient developed diabetes insipidus. Twenty patients were treated by transcranial surgery, of which two were cured, while 17 patients developed postoperative anterior pituitary hormone deficiency. In total, five of the patients who were not cured after surgery were given conventional radiotherapy, of which two were cured. Four of 15 patients, on whom Gamma Knife radiosurgery was performed, were cured. Biochemical remission was achieved in 32 of 52 patients who received octreotide treatment, and in two of five patients who received lanreotide treatment.

CONCLUSIONS

The rate of surgical success in our patients was found to be low. This could be explained by an absence of experienced pituitary surgical centers or surgeons in our region, and the fact that most patients presented late at the macroadenoma stage.

Repeat endoscopic transsphenoidal surgery for acromegaly: remission and complications

Reported biochemical remission rates following surgical intervention for acromegaly range from 38 to 83%. In patients not achieving surgical remission, few options remain, mostly limited to medical management and radiation therapy. There is debate over whether or not to offer reoperation to patients in whom surgical remission is not achieved with initial resection. Retrospective chart review was undertaken to determine all patients having acromegaly with persistently elevated GH and/or IGF-1 levels after initial pituitary adenoma resection, and who underwent reoperation using endoscopic endonasal approach at a single institution. Biochemical remission was defined as a postoperative GH level <1 ng/mL and a normal postoperative IGF-1 level in the absence of any medical therapy. In total, 14 patients underwent repeat surgical intervention for acromegaly via endoscopic transsphenoidal approach. Of the 14 patients, 8 (57%) achieved biochemical remission following repeat surgical intervention. Lower preoperative GH levels were associated with greater chance of biochemical remission (P = 0.048). New endocrinopathies were seen in 2 patients (14%), and both were transient diabetes insipidus. Meningitis occurred in 2 patients (14%); both were aseptic meningitis with no sequelae. No mortality was encountered. Repeat surgical intervention for acromegaly via endoscopic transsphenoidal approach appears safe and effective. With no mortality and minimal morbidity, repeat surgical intervention via endoscopic transsphenoidal approach appears a reasonable option for these hard-to-treat patients and should be considered for patients in whom surgical remission is not achieved with initial surgery.

Results of gamma knife radiosurgery in acromegaly

Objective. Single-session radiosurgery with Gamma Knife (GK) may be a potential adjuvant treatment in acromegaly. We analyzed the safety and efficacy of GK in patients who had previously received maximal surgical debulking at our hospital. Methods. The study was a retrospective analysis of hormonal, radiological, and ophthalmologic data collected in a predefined protocol from 1994 to 2009. The mean age at treatment was 42.3 years (range 22-67 yy). 103 acromegalic patients participated in the study. The median follow-up was 71 months (IQ range 43-107). All patients were treated with GK for residual or recurrent GH-secreting adenoma. Results. Sixty-three patients (61.2%) reached the main outcome of the study. The rate of remission was 58.3% at 5 years (95% CI 47.6-69.0%). Other 15 patients (14.6%) were in remission after GK while on treatment with somatostatin analogues. No serious side effects occurred after GK. Eight patients (7.8%) experienced a new deficit of pituitary function. New cases of hypogonadism, hypothyroidism, and hypoadrenalism occurred in 4 of 77 patients (5.2%), 3 of 95 patients (3.2%), and 6 of 100 patients at risk (6.0%), respectively. Conclusion. In a highly selected group of acromegalic patients, GK treatment had good efficacy and safety.

Therapeutic options in the management of acromegaly: focus on lanreotide Autogel

BACKGROUND

In acromegaly, expert surgery is curative in only about 60% of patients. Postoperative radiation therapy is associated with a high incidence of hypopituitarism and its effect on growth hormone (GH) production is slow, so that adjuvant medical treatment becomes of importance in the management of many patients.

OBJECTIVE

To delineate the role of lanreotide in the treatment of acromegaly.

METHODS

Search of Medline, Embase, and Web of Science databases for clinical studies of lanreotide in acromegaly.

RESULTS

Treatment with lanreotide slow release and lanreotide Autogel((R)) normalized GH and insulin-like growth factor-I (IGF-I) concentrations in about 50% of patients. The efficacy of 120 mg lanreotide Autogel((R)) on GH and IGF-I levels was comparable with that of 20 mg octreotide LAR. There were no differences in improvement of cardiac function, decrease in pancreatic beta-cell function, or occurrence of side effects, including cholelithiasis, between octreotide LAR and lanreotide Autogel(R). When postoperative treatment with somatostatin analogs does not result in normalization of serum IGF-I and GH levels after noncurative surgery, pegvisomant alone or in combination with somatostatin analogs can control these levels in a substantial number of patients.

Treatment of pituitary tumors: radiation

In this paper, the role of conventional radiotherapy and radiosurgery in the management of pituitary tumors is reviewed. After a short summary of the mechanism of action of irradiation therapy and the types of different irradiation techniques, the therapeutic effects and side effects are analyzed in patients with different types of pituitary tumors, including our own experience with conventional radiotherapy and radiosurgery in patients with acromegaly. Conventional fractionated radiotherapy has long been used to control growth and/or hormonal secretion of residual or recurrent pituitary tumors. However, patient selection for conventional radiotherapy still remains a controversial issue, because a number of potentially significant side effects, including hypopituitarism and other complications, have been described. Stereotactic radiotherapy/radiosurgery methods have several potential advantages over conventional radiotherapy, including their use in patients with residual or recurrent pituitary tumors who had previously been treated by conventional radiotherapy, but long-term follow-up data with these relatively new techniques are still limited.

Medical management of growth hormone-secreting pituitary adenomas

The primary treatment of acromegaly remains transsphenoidal adenomectomy, yet the tissue overgrowth of acromegaly often progresses following surgery, and responds to radiotherapy only after significant delay. Persistently elevated serum growth hormone (GH) and insulin-like growth factor-I (IGF-I) concentrations can be normalized in about half of post-surgery acromegalics using the pharmacologic alternatives presently available, the dopamine agonists (DA) and somatostatin (SST) analogs. Cabergoline, the most efficacious DA, normalizes IGF-I in approximately 37% of patients, whereas the long-acting SST analogs, Octreotide LAR and Lanreotide SR, do so in 66%. Significant tumor shrinkage may be attained with SST analogs in particular, and when necessary, the primary medical treatment of acromegaly may be successfully addressed with this class of drugs. Greatly enhanced efficacy is expected from the GH receptor antagonist pegvisomant, which is nearing market availability and will enable the normalization of serum IGF-I in virtually all patients treated. We review here the pharmacologic treatments of excessive GH secretion.

Current status and future opportunities for controlling acromegaly

Growth-hormone (GH) secreting adenomas, including acromegaly, account for approximately one-sixth of all pituitary adenomas and are associated with mortality rates at least twice that of the general population. The ultimate goal of therapy for acromegaly is normalization of morbidity and mortality rates achieved through removal or reduction of the tumor mass and normalization of insulin-like growth factor I (IGF-I) levels. Previously published efficacy results of current treatment modalities (surgery, conventional radiation, and medical therapy with dopamine agonists and somatostatin analogs) are often difficult to compare because of the different criteria used to define cure (some of which are now considered inadequate). For each of these modalities, pooled data from a series of acromegaly studies were reviewed for rates of IGF-I normalization, a currently accepted definition of cure. The results showed overall cure rates of approximately 10% for bromocriptine, 34% for cabergoline, 36% for conventional radiation, 50-90% for surgery for microadenomas and less than 50% for macroadenomas, and 54-66% for octreotide. These cure rates based on IGF-I normalization are generally less than those reported for cure based solely on GH levels. Novel new therapies for acromegaly include the somatostatin analog, lanreotide, Gamma Knife radiosurgery, and pegvisomant, the first in its class of new GH receptor antagonists. Although it does not appear that Gamma Knife radiosurgery results in significantly higher cure rates or fewer complications, it does provide a notable improvement in delivery compared with conventional radiation. Early studies have reported IGF-I normalization in 48% of lanreotide-treated patients and up to 97% of pegvisomant-treated.