Cabergoline versus bromocriptine for the treatment of giant prolactinomas: A quantitative and systematic review

Diagnosis and management of prolactin-secreting pituitary adenomas: a Pituitary Society international Consensus Statement

This Consensus Statement from an international, multidisciplinary workshop sponsored by the Pituitary Society offers evidence-based graded consensus recommendations and key summary points for clinical practice on the diagnosis and management of prolactinomas. Epidemiology and pathogenesis, clinical presentation of disordered pituitary hormone secretion, assessment of hyperprolactinaemia and biochemical evaluation, optimal use of imaging strategies and disease-related complications are addressed. In-depth discussions present the latest evidence on treatment of prolactinoma, including efficacy, adverse effects and options for withdrawal of dopamine agonist therapy, as well as indications for surgery, preoperative medical therapy and radiation therapy. Management of prolactinoma in special situations is discussed, including cystic lesions, mixed growth hormone-secreting and prolactin-secreting adenomas and giant and aggressive prolactinomas. Furthermore, considerations for pregnancy and fertility are outlined, as well as management of prolactinomas in children and adolescents, patients with an underlying psychiatric disorder, postmenopausal women, transgender individuals and patients with chronic kidney disease. The workshop concluded that, although treatment resistance is rare, there is a need for additional therapeutic options to address clinical challenges in treating these patients and a need to facilitate international registries to enable risk stratification and optimization of therapeutic strategies.

Surgical Management of Giant Prolactinomas: A Descriptive Study

Introduction

Giant prolactinoma (GP) is a rare pituitary lactotropic cell tumor larger than 4 cm in its widest dimension, and is less likely than a smaller prolactinoma to achieve prolactin normalization on dopamine agonist (DA) monotherapy. There is a paucity of data on the circumstances and outcomes of second-line management of GP with surgery. Herein, our institution's experience with the surgical management of GPs is described.

Methods

A single-center retrospective analysis was conducted of patients who underwent surgery for giant prolactinoma from 2003 to 2018. A chart review was conducted for demographic data, clinical features, laboratory and radiographic findings, operative and pathology reports, perioperative management, and clinical outcomes in follow-up. Descriptive statistics were used.

Results

Of 79 prolactinoma cases, 8 patients had GP with a median age of 38 years (range 20-53), 75% (6/8) were male, with a median largest tumor dimension of 6 cm (range 4.6-7.7), and a median prolactin level of 2,500 μg/L (range 100->13,000). Six patients had transsphenoidal surgery for dopamine agonist (DA) resistance or intolerance. Two patients had a craniotomy for a missed diagnosis; one was due to the hook effect. No tumor resections were complete by either surgical approach; all had persistent hyperprolactinemia requiring postoperative DA therapy, and two patients had an additional craniotomy procedure for further tumor debulking. There was no recovery of pituitary axes and postoperative deficits were common. Remission as defined by prolactin normalization occurred in 63% (5/8) at a median time of 36 months (range 14-63 months) on DA therapy after surgery with a follow-up of 3-13 years.

Conclusions

GPs infrequently require surgical resection, which is generally incomplete and requires adjuvant therapy. Given the rarity of surgery for GPs, multi-institutional or registry studies would yield clearer guidance on optimal management.

A case of acute hydrocephalus due to a giant prolactinoma rescued by transventricular neuroendoscopic tumorectomy

Background

A giant prolactinoma extending to the suprasellar area and causing hydrocephalus may be life-threatening and should be treated promptly. A case of a giant prolactinoma with acute hydrocephalus that underwent transventricular neuroendoscopic tumor resection followed by cabergoline administration is presented.

Case Description

A 21-year-old man had a headache lasting for about a month. He gradually developed nausea and disturbance of consciousness. Magnetic resonance imaging showed a contrast-enhanced lesion that extended from the intrasellar space to the suprasellar space and into the third ventricle. The tumor obstructed the foramen of Monro and caused hydrocephalus. A blood test showed marked elevation of prolactin (16,790 ng/mL). The tumor was diagnosed as a prolactinoma. The tumor in the third ventricle had formed a cyst, and the cyst wall blocked the right foramen of Monro. The cystic component of the tumor was resected using an Olympus VEF-V flexible neuroendoscope. The histological diagnosis was pituitary adenoma. The hydrocephalus improved rapidly and his consciousness became clear. After the operation, he was started on cabergoline. The tumor size subsequently decreased.

Conclusion

Prompt partial resection of the giant prolactinoma by transventricular neuroendoscopy resulted in early improvement of hydrocephalus with less invasiveness, allowing subsequent treatment with cabergoline.

Brusatol Inhibits Tumor Growth and Increases the Efficacy of Cabergoline against Pituitary Adenomas

Cabergoline (CAB) is the first choice for treatment of prolactinoma and the most common subtype of pituitary adenoma. However, drug resistance and lack of effectiveness in other pituitary tumor types remain clinical challenges to this treatment. Brusatol (BT) is known to inhibit cell growth and promote apoptosis in a variety of cancer cells. In our present studies, we investigate the effects of BT on pituitary tumor cell proliferation in vitro and in vivo. BT treatment resulted in an increase in Annexin V-expressing cells and promoted the expression of apoptosis-related proteins in rat and human pituitary tumor cells. Investigation of the mechanism underlying this effect revealed that BT increased the production of reactive oxygen species (ROS) and inhibited the phosphorylation of 4EBP1 and S6K1. Furthermore, treatment with a combination of BT and CAB resulted in greater antitumor effects than either treatment alone in nude mice and pituitary tumor cells. Collectively, our results suggest that the BT-induced ROS accumulation and inhibition of mTORC1 signaling pathway leads to inhibition of tumor growth. Combined use of CAB and BT may increase the clinical effectiveness of treatment for human pituitary adenomas.

Giant Prolactinoma Presenting With Facial Nerve Palsy and Hemiparesis

Background

Giant prolactinomas are an exceedingly uncommon type of pituitary adenomas that usually occur in men, and cause extremely high prolactin levels and mass-related symptoms. Rarely, patients may experience neurological deficits resembling ischemic events.

Methods

We describe an unusual case of a young man who presented with stroke-like symptoms and was found to have a giant prolactinoma.

Clinical Case

A 25-year-old man presented with left facial droop and gradually progressing upper and lower extremity weakness for evaluation of stroke. He reported recent weight gain and erectile dysfunction. Physical examination revealed left homonymous hemianopsia, left VII nerve palsy, and left hemiparesis. Magnetic resonance imaging of the brain showed an enormous mass in the sella turcica, which invaded the sphenoid sinus and right side of the skull base. Prolactin level was elevated at 13 580 ng/mL, and the testosterone level was low. The patient was started on cabergoline and had marked improvement in his symptoms in a few months. Fifteen months after starting treatment, he has had more than 90% reduction in tumor volume and a 93% reduction in prolactin level.

Conclusion

Giant prolactinomas are uncommon and present with compressive symptoms that can be mistaken for a stroke. Our case is a unique report of a facial nerve palsy and hemiparesis secondary to giant prolactinoma in the absence of stroke or pituitary apoplexy.

The Role of Dopamine Agonists in Pituitary Adenomas

Dopamine agonist therapy is the primary therapy for prolactin-secreting adenomas and usually results in normoprolactinemia, eugonadism, and tumor reduction. Cabergoline is superior to bromocriptine with regard to efficacy and tolerance. Withdrawal of cabergoline can be attempted in patients with normal prolactin levels on low doses of medication and evidence of radiographic tumor involution. Dopamine agonists have been used off label in patients with acromegaly, Cushing disease, and nonfunctioning adenomas. A trial of cabergoline monotherapy can be effective in patients with biochemically mild acromegaly. Cabergoline combination with somatostatin receptor ligands or pegvisomant improves insulin-like growth factor level 1 in majority of patients.

Treatment of Pituitary and Other Tumours with Cabergoline: New Mechanisms and Potential Broader Applications

Cabergoline is a dopamine agonist that has been used as the first-line treatment option for prolactin-secreting pituitary adenomas for several decades. It not only suppresses hormone production from these prolactinomas, but also causes tumour shrinkage. Recent studies revealed some novel mechanisms by which cabergoline suppresses tumour cell proliferation and induces cell death. In this article, we review the most recent findings in cabergoline studies, focusing on its anti-tumour function. These studies suggest the potential broader clinical use of cabergoline in the treatment of other tumours such as breast cancer, pancreatic neuroendocrine tumours, and lung cancer.

Giant Prolactinomas

Prolactin-secreting adenomas (prolactinomas) are the most common secreting adenomas of the pituitary. Microprolactinomas (diameter <10 mm) are frequently diagnosed in women, whereas macroprolactinomas (maximum diameter ≥10 mm) are generally seen in men. Most macroprolactinomas measure between 10 and 40 mm. Giant prolactinomas, measuring >40 mm, are rare, accounting for only 1-5% of all prolactinomas. Although generally benign, giant prolactinomas are aggressive and invasive, extending into the suprasellar region and also involving the cavernous sinuses. The optic chiasm is frequently involved, which leads to visual damage, and patients occasionally suffer from ophthalmoplegia. Long-term (usually lifetime) therapy with high-dose dopamine agonists (cabergoline or bromocriptine), together with pituitary surgery in some cases and radiotherapy if required, can achieve biochemical remission, tumor control, and clinical improvement in most patients.

Cabergoline for the treatment of bromocriptine-resistant invasive giant prolactinomas

PURPOSE

Few studies have specifically focused on the effect of cabergoline on invasive giant prolactinomas (IGPs) resistant to bromocriptine. This study aims to evaluate whether cabergoline could be used as an effective therapy for patients with bromocriptine-resistant IGPs.

METHODS

This retrospective study included 15 patients with bromocriptine-resistant IGPs who received treatment at our department during 2007-2015. Cabergoline was administered in all 15 patients, with the dose adjusted depending on the prolactin response of each patient. Parameters for outcome assessment included prolactin level, pituitary function, tumor size, improvement of the clinical symptoms, visual field defects, drug tolerance, and disease recurrence.

RESULTS

Cabergoline was effective for the treatment of the patients with bromocriptine -resistant IGPs as represented by normalization of the prolactin level in 12/15 patients; improvement or normalization of the pituitary function in 4/5 patients with hypopituitarism; significant reduction in tumor size in 14/15 patients; and relief of the clinical symptoms in 11/15 patients. All 15 patients showed good tolerance to cabergoline. In addition, no recurrence was observed during the mean follow-up period of 63.47 (range 30-145) months.

CONCLUSIONS

Data of this retrospective study demonstrate that cabergoline is an excellent option for the treatment of patients with bromocriptine-resistant IGPs.