Reduction in the size of prolactin-producing pituitary tumor after Cabergoline administration

Treatment of Prolactinoma

Prolactinomas are the commonest form of pituitary neuroendocrine tumor (PitNET), representing approximately half of such tumors. Dopamine agonists (DAs) have traditionally been the primary treatment for the majority of prolactinomas, with surgery considered the second line. The aim of this review is to examine the historical and modern management of prolactinomas, including medical therapy with DAs, transsphenoidal surgery, and multimodality therapy for the treatment of aggressive prolactinomas and metastatic PitNETs, with an emphasis on the efficacy, safety, and future directions of current therapeutic modalities. DAs have been the mainstay of prolactinoma management since the 1970s, initially with bromocriptine and more recently with cabergoline. Cabergoline normalizes prolactin in up to 85% of patients and causes tumor shrinkage in up to 80%. Primary surgical resection of microprolactinomas and enclosed macroprolactinomas performed by experienced pituitary neurosurgeons have similar remission rates to cabergoline. Aggressive prolactinomas and metastatic PitNETS should receive multimodality therapy including high dose cabergoline, surgery, radiation therapy (preferably using stereotactic radiosurgery where suitable), and temozolomide. DAs remain a reliable mode of therapy for most prolactinomas but results from transsphenoidal surgery in expert hands have improved considerably over the last one to two decades. Surgery should be strongly considered as primary therapy, particularly in the setting of microprolactinomas, non-invasive macroprolactinomas, or prior to attempting pregnancy, and has an important role in the management of DA resistant and aggressive prolactinomas.

Dopamine agonist therapy for prolactinomas: do we need to rethink the place of surgery in prolactinoma management?

The current treatment paradigm for prolactinomas involves dopamine agonist (DA) therapy as the first-line treatment, with surgical resection reserved for cases where there is DA failure due to resistance or intolerance. This review highlights how DA therapy can be optimised to overcome its increasingly recognised pitfalls, whilst also addressing the potential for expanding the use of surgery in the management of prolactinomas. The first part of the review discusses the limitations of DA therapy, namely: DA resistance; common DA side effects; and the rare but serious DA-induced risks of cardiac valvulopathy, impulse control disorders, psychosis, CSF rhinorrhoea and tumour fibrosis. The second part of the review explores the role of surgery in prolactinoma management with reference to its current second-line position and recent calls for surgery to be considered as an alternative first-line treatment alongside DA therapy. Randomised trials comparing medical vs surgical therapy for prolactinomas are currently underway. Pending these results, a low surgical threshold approach is herein proposed, whereby DA therapy remains the default treatment for prolactinomas unless there are specific triggers to consider surgery, including concern regarding DA side effects or risks in vulnerable patients, persistent and bothersome DA side effects, emergence of any serious risks of DA therapy, expected need for long-term DA therapy, as well as the traditional indications for surgery. This approach should optimise the use of DA therapy for those who will most benefit from it, whilst instituting surgery early in others in order to minimise the cumulative burden of prolonged DA therapy.

UNDERSTANDING PROLACTIN REGULATION AND DETERMINING THE EFFICACY OF CABERGOLINE AND DOMPERIDONE TO MITIGATE PROLACTIN-ASSOCIATED OVARIAN CYCLE PROBLEMS IN ZOO AFRICAN ELEPHANTS (LOXODONTA AFRICANA )

Perturbations in serum prolactin secretion, both over- and underproduction, are observed in zoo African elephants (Loxodonta africana) that exhibit abnormal ovarian cycles. Similar prolactin problems are associated with infertility in other species. Pituitary prolactin is held under constant inhibition by a hypothalamic-derived neurotransmitter, dopamine; thus, regulation by exogenous treatment with agonists or antagonists may be capable of reinitiating normal ovarian cycles. This study tested the efficacy of oral administration of cabergoline (agonist) and domperidone (antagonist) as possible treatments for hyperprolactinemia or chronic low prolactin, respectively. Hyperprolactinemic (overall mean prolactin, >30 ng/ml), acyclic elephants were administered oral cabergoline (2 mg, n = 4) or placebo (dextrose capsule, n = 4) twice weekly. Overall mean prolactin concentration decreased in treated females compared with controls (32.22 ± 14.75 vs 77.53 ± 0.96 ng/ml; P = 0.01). Interestingly, overall mean progestagen concentrations also increased slightly (P < 0.05) in treated females (0.15 ± 0.01 ng/ml) compared with controls (0.07 ± 0.01 ng/ml), but no reinitation of normal cyclic patterns was observed. Chronic low prolactin (overall mean prolactin, <10 ng/ml), acyclic females were orally administered domperidone (2 g/day, n = 4) or placebo (dextrose capsule, n = 4) for 4 wk, followed by 8 wk of no treatment (four cycles) to simulate the prolactin pattern observed in normal cycling elephants. Overall mean prolactin concentrations increased (P = 0.005) during domperidone treatment (21.77 ± 3.69 ng/ml) compared with controls (5.77 ± 0.46 ng/ml), but progestagen concentrations were unaltered. Prolactin regulation by dopamine was confirmed by expected responses to dopamine agonist and antagonist treatment. Although prolactin concentrations were successfully reduced by cabergoline, and domperidone initiated the expected cyclic prolactin pattern, neither treatment induced normal ovarian activity.

Hyperprolactinemia and prolactinomas

Any process interfering with dopamine synthesis, its transport to the pituitary gland, or its action at the level of lactotroph dopamine receptors can cause hyperprolactinemia. As described in this article, considering the complexity of prolactin regulation, many factors could cause hyperprolactinemia, and hyperprolactinemia can have clinical effects not only on the reproductive axis. Once any drug effects are excluded, prolactinomas are the most common cause of hyperprolactinemia. The most frequent symptom is hypogonadism in both genders. Medical and surgical therapies generally have excellent results, and most prolactinomas are well controlled or even cured in some cases.

Medical management of prolactin-secreting pituitary adenomas

Prolactinomas are a common cause of reproductive/sexual dysfunction. Once other causes of hyperprolactinemia have been excluded with a careful history and physical examination, routine chemistries, a pregnancy test and a TSH, imaging with MRI or CT will delineate the size and extent of the tumor. Medical therapy is the initial treatment of choice. When infertility is the primary indication for treatment, bromocriptine use has an extensive safety experience and is preferred. However, for other indications, cabergoline appears to be more efficacious and better tolerated. Transsphenoidal surgery remains an option, especially for patients with microadenomas, when medical therapy is ineffective.

Disorders of prolactin secretion

Prolactinomas are a common cause of reproductive/sexual dysfunction. Once other causes of hyperprolactinemia have been excluded with a careful history and physical examination, routine chemistries, and an assay for TSH, MR imaging, or CT will delineate the size and extent of the tumor. Medical therapy is the initial treatment of choice. When infertility is the primary indication for treatment, bromocriptine use has an extensive safety record and is preferred. For other indications, cabergoline seems to be more efficacious and better tolerated. Transsphenoidal surgery remains an option, especially for patients with microadenomas, when medical therapy is ineffective.

Cabergoline as a first-line treatment in newly diagnosed macroprolactinomas

There are few long-term studies of cabergoline (CAB) administration in patients with macroprolactinomas. All of these studies included different type of patients, such as patients with idiopathic hyperprolactinemia, microprolactinomas and previously treated or untreated macroprolactinomas. We report a study of CAB treatment conducted exclusively in patients with newly diagnosed, untreated, macroprolactinomas. Twelve patients (6 M, 6 F) with macropolactinomas were investigated prospectively for 12 months to determine the effects of prolonged treatment with CAB on serum PRL levels, tumor size, visual fields and prevalence of side effects. Nine of these patients continued therapy and follow-up for 6 or more additional months of CAB administration. Our results demonstrated that CAB decreased the volume of the tumor in all patients investigated 3 months after the initiation of treatment. Specifically, mean tumor volume was 11,327 +/- 25,187 mm3 before the study and decreased to 4281 +/- 8465 mm3 and 1544 +/- 2118 mm3 in the second and last measurement, respectively. However, these changes were not statistically significant, most probably due to the very high SD. As far as the maximum diameter is concerned, mean values was 22.8 +/- 16.9 mm before the study and decreased to 16.6 +/- 10.9 mm and 13.4 +/- 7.5 mm in the 3 months and last examination, respectively. These changes were statistically significant (p = 0.005 and p = 0.007). The mean percentage decrease of the tumor volume and maximum tumor diameter was 42.4 +/- 14.0% and 24.7 +/- 4.8% respectively in the third month and 67.2 +/- 17.3% and 35.9 +/- 11.8% in the last estimation. These differences were statistically significant, (p < 0.01 and p < 0.001, respectively). The same was also true for PRL levels, the mean of which was 14,719 +/- 20,616 before treatment and became normal in the third month (153.3 +/- 63.4) and continued to be throughout the study. Four patients had visual field defects, which improved or even completely resolved during the treatment period. Finally, the CAB doses used were particularly small, i.e., 0.5-2 mg per week. All the patients recovered from their clinical problems and symptoms. This remarkable improvement was associated with an excellent tolerability of the long-term treatment due to the low incidence of side effects. In conclusion, the results of the present study demonstrated that CAB produced tumor shrinkage and normalized PRL levels in all the patients studied. Also, clinical symptoms disappeared and visual fields improved. These beneficial effects were associated with a very high compliance rate and minimal side effects. Thus, CAB can be considered a first-line pharmacological treatment of macroprolactinomas.

Cabergoline: a first-choice treatment in patients with previously untreated prolactin-secreting pituitary adenoma

Cabergoline (CAB) treatment is an effective, safe and well tolerated approach for hyperprolactinemia. We investigated the efficacy of 24-month treatment with CAB in 37 patients with previously untreated PRL-secreting pituitary adenoma and evaluated the hormonal and neuroradiological changes after the discontinuation of long-term therapy. Eleven patients with macroprolactinoma (1M/10F) and 26 with microprolactinoma (4M/22F) started treatment taking 0.25 mg CAB twice a week for 4 weeks. The dose was increased stepwise in 0.5 mg increments until reaching lowest maximally effective and tolerated dose. CAB was withdrawn before the end of the study in 6 women who became pregnant and in one patient who showed a slight increase of the macroadenoma at MRI. During treatment, PRL levels decreased significantly in macro (11.1+/-1.1 vs 407.8+/-98.3 microg/l, p<0.001) and microprolactinomas (11.1+/-1.6 vs 193.8+/-23.4 microg/l, p<0.05) and normalized in all macro and in 23/26 microprolactinomas. In 3 cases PRL levels decreased but did not normalize because the appearance of side effects, such as nausea or hypotension, prevented the increase of the dose of CAB. The effective dose of drug correlated significantly with basal serum PRL levels (p<0.05) and with the pituitary tumor size (p<0.05). A significant decrease of the mean adenoma size was evident for macro (6.9+/-1.8 vs 16.0+/-1.8 mm, p<0.001) and microprolactinomas (3.0+/-0.5 vs 6.5+/-0.4 mm, p<0.001) at MRI. The tumor disappeared in 4 macroadenomas and in 11 microadenomas after 12 months of treatment. CAB withdrawal was followed by serum PRL increase in 13 cases after 3 months, in 6 after 6 months, in 2 after 9 months, and in one patient at the 12th month. Five patients showed normoprolactinemia with negative MRI after one year. Regular menses were restored in 7/10 macroprolactinomas and in all oligo-amenorrhoic patients with microadenoma; serum testosterone levels normalized in 2/3 hypogonadic men. Five out of 6 women become pregnant and had uneventful pregnancies which resulted in deliveries of normal babies. In conclusion, this study confirms the effectiveness and safety of CAB for patients with PRL-secreting pituitary adenoma and suggests that it can be considered a first choice treatment.

Medical treatment of prolactinomas

Prolactinomas are a common cause of reproductive and sexual dysfunction. Once other causes of hyperprolactinemia have been excluded with a careful history, physical examination, routine chemistries, and a TSH, MR imaging or computerized tomography will delineate the size and extent of the tumor. Medical therapy is the initial treatment of choice. When infertility is the primary indication for treatment, bromocriptine use has an extensive safety experience and is preferred. For other indications, however, cabergoline appears to be more efficacious and better tolerated. Transsphenoidal surgery remains an option, especially for patients with microadenomas, when medical therapy is ineffective.

The chronic administration of cabergoline normalizes androgen secretion and improves menstrual cyclicity in women with polycystic ovary syndrome

OBJECTIVE

To investigate whether the administration of the long-lasting dopaminergic drug, cabergoline, improves endocrine and clinical features of women with polycystic ovary syndrome (PCOS).

PATIENTS

Twenty-nine women participated in the study: 14 women with clinical and endocrinologic features of PCOS and 15 age- and weight-matched normal cycling women. Each subject was assigned randomly to receive either a tablet of cabergoline at the dose of 0.5 mg/wk or placebo for 4 months. Sixteen subjects (PCOS: n = 8; controls: n = 8) received cabergoline, whereas 13 (PCOS: n = 6; controls: n = 7) received placebo.

INTERVENTIONS

Both before and during the 4th month of treatment, blood samples were collected every 10 minutes from 9:00 A.M. to 3:00 P.M., 3 to 7 days after spontaneous or medroxy-progesterone acetate (MPA; 5 mg daily for 5 days)-induced menses. Follicle-stimulating hormone and androgen levels were measured in the basal samples, whereas LH levels were measured in all samples.

MAIN OUTCOME MEASURES

Menstrual cyclicity, LH pulsatility, and circulating levels of FSH, PRL, E2, total T, free T, androstenedione, 17 alpha-hydroxyprogesterone, DHEAS, and sex hormone-binding globulin.

RESULTS

Both in controls and in PCOS-affected women, cabergoline administration blunted plasma PRL levels without affecting LH pulsatility. Androgen levels were reduced in controls and normalized in PCOS. Cabergoline, but not placebo, induced menses reappearance in amenorrheic and a normalization of menstrual cyclicity in oligoamenorrheic women with PCOS.

CONCLUSIONS

The administration of cabergoline is capable to normalize androgen levels and to improve menstrual cyclicity in PCOS-affected women. Cabergoline may represent an useful treatment for menstrual irregularities of PCOS patients.

Effectiveness of cabergoline in reducing follicle-stimulating hormone and prolactin hypersecretion from pituitary macroadenoma in an infertile woman

Dopaminergic drugs have been reported to be effective in the treatment of FSH-secreting adenomas. We describe the case of a young woman suffering from amenorrhea with radiologic signs of pituitary macroadenoma. The enlargement of both ovaries with hemorrhagic and serous cysts suggest that FSH was active biologically. The short-term (13 weeks) chronic treatment with 0.5 mg cabergoline one time per week, a dopaminergic drug with long-lasting effect, was effective in reducing FSH and PRL hypersecretion and restoring the function of the pituitary ovarian axis, as confirmed by the occurrence of pregnancy.

[Treatment of prolactinoma]

Prolactinomas rank first in frequency among hormone-secreting pituitary adenomas, but their management remains controversial. The authors present a review of the literature concerning the various therapeutic methods used and their results. As regards microadenomas, opinions are divided since the results obtained with bromocriptine and with selective adenomectomy are about the same. As regards macroadenomas, surgery exposes to more frequent complications and above all to recurrences. The majority of authors is in favour of bromocriptine first followed, if necessary, by surgical excision. Pregnancy may accelerate the development of prolactinomas. This risk is minimal with microadenomas and more real with macroadenomas, requiring more radical treatment before pregnancy and close monitoring.