Clinical use of aromatase inhibitors (AI) in premenopausal women

Incidence and Predictive Factors for Recovery of Ovarian Function in Amenorrheic Women in Their 40s Treated With Letrozole

PURPOSE

This prospective study assessed the impact of 2 years of aromatase inhibitor (AI) therapy on the incidence of ovarian function recovery (OFR) in women age 40 to 49 with estrogen receptor-positive breast cancer who were premenopausal at diagnosis and who underwent chemotherapy-induced amenorrhea during adjuvant treatment.

PATIENTS AND METHODS

Women age 40 to 49 with estrogen receptor-positive breast cancer who had ceased menstruating with adjuvant cyclophosphamide-based chemotherapy, had postmenopausal serum estradiol (E2), and had received tamoxifen for ≥ 1 year were treated with letrozole (2.5 mg) daily for ≥ 2 years. Serum follicle-stimulating hormone (FSH) and E2 were measured at baseline and over 2 years. A general linear model was used to assess serial FSH by OFR. Logistic regression was used to assess baseline predictors and OFR.

RESULTS

The study enrolled 177 women (145 women age 45 to 49 years and 32 women age 40 to 44 years). Of 173 evaluable patients, 67 (39%; 95% CI, 31% to 46%) regained ovarian function; 11 of these patients (6%; 95% CI, 3% to 10%) resumed menses, and 56 of these patients (32%; 95% CI, 25% to 39%) developed premenopausal E2 without menses. Among AI-naïve patients, serial FSH significantly increased over time (P < .001), did not vary significantly by OFR status (P = .55), but showed mild evidence of a decrease after month 12 for those who resumed menses (P = .0989). Age less than 45 years and inhibin B were significant multivariable baseline predictors of OFR.

CONCLUSION

These results emphasize the challenge in determining definitive menopause in women with chemotherapy-induced amenorrhea. The risk of OFR during treatment with AIs in amenorrheic women in their 40s is high, and AI therapy should be avoided in these patients.

Chemotherapy-induced ovarian toxicity in patients affected by endocrine-responsive early breast cancer

Cytotoxic chemotherapy may variably affect ovarian function depending on age and ovarian reserve at diagnosis, type of chemotherapy and use of tamoxifen. Ascertaining whether a premenopausal patient with endocrine-responsive early breast cancer and chemotherapy-induced amenorrhea has reached menopause is essential not only in order to provide accurate information on residual fertility, but also to appropriately prescribe endocrine therapy. Indeed, aromatase inhibitors are contraindicated in women with residual ovarian reserve. However, the diagnosis of menopause in patients with chemotherapy-induced amenorrhea is challenging, since clinical features, follicle-stimulating hormone and estradiol levels may be inaccurate to this aim. Recent studies demonstrated that the anti-müllerian hormone may improve the assessment of ovarian reserve residual to chemotherapy in women with early breast cancer. Herein, we review the incidence of amenorrhea and menopause induced by cytotoxic chemotherapy in women affected by early breast cancer and the suggested mechanisms that sustain these side-effects. Furthermore, it has been scrutinized the potential of new markers of ovarian reserve that may facilitate the selection of appropriate endocrine treatment for premenopausal women who develop amenorrhea following adjuvant chemotherapy for early breast cancer.

Recognizing menopause in women with amenorrhea induced by cytotoxic chemotherapy for endocrine-responsive early breast cancer

Cytotoxic anticancer treatment may induce amenorrhea or menopause to a variable extent. These side effects may not only impair or impede fertility but also cause sexual dysfunction, bone loss, and menopausal symptoms, with a strikingly negative effect on quality of life in many women. Aromatase inhibitors (AIs) are a recommended adjuvant endocrine treatment option in postmenopausal patients affected by early breast cancer (EBC) but are contraindicated in premenopausal women and in those with residual ovarian function. Women over 40 years of age with chemotherapy-induced amenorrhea (CIA) and routine hormonal levels consistent with menopause may receive an AI as adjuvant endocrine treatment. For these women, the tools available to identify menopause do not appear to be completely reliable. This review focused on the pathophysiology of ovarian toxicity induced by cytotoxic agents and on potentially useful methods to diagnose chemotherapy-induced menopause in patients treated with adjuvant chemotherapy for endocrine-responsive EBC. Moreover, practical approaches are proposed to distinguish true menopausal women, who would benefit from AIs, from those with transient or persistent CIA.

The advantage of letrozole over tamoxifen in the BIG 1-98 trial is consistent in younger postmenopausal women and in those with chemotherapy-induced menopause

Letrozole, an aromatase inhibitor, is ineffective in the presence of ovarian estrogen production. Two subpopulations of apparently postmenopausal women might derive reduced benefit from letrozole due to residual or returning ovarian activity: younger women (who have the potential for residual subclinical ovarian estrogen production), and those with chemotherapy-induced menopause who may experience return of ovarian function. In these situations tamoxifen may be preferable to an aromatase inhibitor. Among 4,922 patients allocated to the monotherapy arms (5 years of letrozole or tamoxifen) in the BIG 1-98 trial we identified two relevant subpopulations: patients with potential residual ovarian function, defined as having natural menopause, treated without adjuvant or neoadjuvant chemotherapy and age ≤ 55 years (n = 641); and those with chemotherapy-induced menopause (n = 105). Neither of the subpopulations examined showed treatment effects differing from the trial population as a whole (interaction P values are 0.23 and 0.62, respectively). Indeed, both among the 641 patients aged ≤ 55 years with natural menopause and no chemotherapy (HR 0.77 [0.51, 1.16]) and among the 105 patients with chemotherapy-induced menopause (HR 0.51 [0.19, 1.39]), the disease-free survival (DFS) point estimate favoring letrozole was marginally more beneficial than in the trial as a whole (HR 0.84 [0.74, 0.95]). Contrary to our initial concern, DFS results for young postmenopausal patients who did not receive chemotherapy and patients with chemotherapy-induced menopause parallel the letrozole benefit seen in the BIG 1-98 population as a whole. These data support the use of letrozole even in such patients.

Letrozole and norethisterone acetate versus letrozole and triptorelin in the treatment of endometriosis related pain symptoms: a randomized controlled trial

BACKGROUND

When aromatase inhibitors are used to treat premenopausal women with endometriosis, additional drugs should be used to effectively down-regulate gonadal estrogen biosynthesis. This randomized prospective open-label study compared the efficacy in treating pain symptoms and the tolerability of letrozole combined with either norethisterone acetate or triptorelin.

METHODS

Women with pain symptoms caused by rectovaginal endometriosis were treated with letrozole (2.5 mg/day) and were randomized to also receive either oral norethisterone acetate (2.5 mg/day; group N) or intramuscular injection of triptorelin (11.25 mg every 3 months; group T). The scheduled length of treatment was 6 months. A visual analogue scale and a multidimensional categorical rating scale were used to assess the severity of pain symptoms. The volume of the endometriotic nodules was estimated by ultrasonography using virtual organ computer-aided analysis. Adverse effects of treatment were recorded.

RESULTS

A total of 35 women were randomized between the two treatment protocols. Significantly more patients in group N rated their treatment as satisfactory or very satisfactory (64.7%) as compared to group T (22.2%; p=0.028). The intensity of both non-menstrual pelvic pain and deep dyspareunia significantly decreased during treatment in both study groups, though no statistically meaningful difference between the two groups was apparent. Reduction in the volume of endometriotic nodules was significantly greater in group T than in group N. Interruption of treatment due to adverse effects significantly differed between the groups, with 8 women in group T (44.4%) and 1 woman in group N (5.9%) interrupting treatment (p=0.018). Similarly, 14 women included in group T (77.8%) and 6 women included in group N (35.3%) experienced adverse effects of treatment (p=0.018). During treatment, mineral bone density significantly decreased in group T but not in group N.

CONCLUSIONS

Aromatase inhibitors reduce the intensity of endometriosis-related pain symptoms. Combining letrozole with oral norethisterone acetate was associated with a lower incidence of adverse effects and a lower discontinuation rate than combining letrozole with triptorelin.

Plasma 25-hydroxyvitamin D and risk of breast cancer in the Nurses' Health Study II

Introduction

Experimental evidence indicates vitamin D may play an important role in breast cancer etiology but epidemiologic evidence to date is inconsistent. Vitamin D comes from dietary intake and sun exposure and plasma levels of 25-hydroxyvitamin D (25(OH)D) are considered the best measure of vitamin D status.

Methods

We conducted a prospective nested case-control study within the Nurses' Health Study II (NHSII). Plasma samples collected in 1996 to 1999 were assayed for 25(OH)D in 613 cases, diagnosed after blood collection and before 1 June 2007, and in 1,218 matched controls. Multivariate relative risks (RR) and 95% confidence intervals (CI) were calculated by conditional logistic regression, adjusting for several breast cancer risk factors.

Results

No significant association was observed between plasma 25(OH)D levels and breast cancer risk (top vs. bottom quartile multivariate RR = 1.20, 95% CI (0.88 to 1.63), P-value, test for trend = 0.32). Results were similar when season-specific quartile cut points were used. Results did not change when restricted to women who were premenopausal at blood collection or premenopausal at diagnosis. Results were similar between estrogen receptor (ER)+/progesterone receptor (PR)+ and ER-/PR- tumors (P-value, test for heterogeneity = 0.51). The association did not vary by age at blood collection or season of blood collection, but did vary when stratified by body mass index (P-value, test for heterogeneity = 0.01).

Conclusions

Circulating 25(OH)D levels were not significantly associated with breast cancer risk in this predominantly premenopausal population.

Aromatase inhibitors in the treatment of bladder endometriosis

BACKGROUND

Aromatase inhibitors have recently been proposed for the treatment of endometriosis; however, no previous study examined the effects of these agents on pain and urinary symptoms of premenopausal women with bladder endometriosis.

CASE

Two premenopausal patients with bladder endometriosis were treated with letrozole (2.5 mg/day), norethisterone acetate (2.5 mg/day), elemental calcium and vitamin D3 for 6 months. The double-drug regimen quickly improved pain and urinary symptoms in both patients. One patient had no significant adverse effect and continued the therapy for 14 months. The other patient developed myalgia and severe arthralgia; pain and urinary symptoms recurred few months after the interruption of the 6-month treatment and the patient underwent laparoscopic partial cystectomy.

CONCLUSION

Aromatase inhibitors improve pain and urinary symptoms in patients with bladder endometriosis; however, severe side effects of treatment may occur. These agents should be administered only to patients who refuse surgery and fail to respond to other therapies.

Use of aspirin, other nonsteroidal anti-inflammatory drugs, and acetaminophen and risk of breast cancer among premenopausal women in the Nurses' Health Study II

BACKGROUND

The use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) is widespread for treatment of common symptoms such as headaches, muscular pain, and inflammation. In addition, the chemopreventive use of NSAIDs is increasingly common for heart disease and colon cancer. Evidence of a protective association with breast cancer risk has been inconsistent, and few data exist for premenopausal women.

METHODS

We assessed the associations for use of aspirin, other NSAIDs, and acetaminophen with breast cancer risk among premenopausal women in the prospective Nurses' Health Study II. In total, 112,292 women, aged 25 to 42 years and free of cancer in 1989, were followed up until June 2003. Multivariate relative risks and 95% confidence intervals were calculated by Cox proportional hazards models, adjusting for age and other important breast cancer risk factors.

RESULTS

Overall, 1345 cases of invasive premenopausal breast cancer were documented. Regular use of aspirin (> or = 2 times per week) was not significantly associated with breast cancer risk (relative risk, 1.07; 95% confidence interval, 0.89-1.29). Regular use of either nonaspirin NSAIDs or acetaminophen also was not consistently associated with breast cancer risk. Results did not vary by frequency (days per week), dose (tablets per week), or duration of use. Furthermore, associations with each drug category did not vary substantially by estrogen and progesterone receptor status of the tumor.

CONCLUSION

These data suggest that the use of aspirin, other NSAIDs, and acetaminophen is not associated with a reduced risk of breast cancer among premenopausal women.

Optimizing the antihormonal treatment and prevention of breast cancer

The incidence of breast cancer is rising throughout the world. Breast cancer is slowly becoming more prevalent in countries which previously had low rates of cancer as well as becoming a leading cause of cancer death in some countries. Fortunately, a large number of these tumors are estrogen receptor (ER) positive and respond to anti-hormonal adjuvant therapy which until recently has been 5 years of tamoxifen treatment. Unfortunately, a significant number of patients develop recurrent cancers and the recurrent tumors are resistant to tamoxifen treatment. In addition, because of tamoxifen's selective estrogenic actions, there have been reports of venous thrombosis, endometrial cancer, and strokes in patients receiving tamoxifen therapy. Thus, there are other novel therapies such as aromatase inhibitors that block estrogen production in postmenopausal women or fulvestrant that destroys the estrogen receptor. This paper will summarize the therapeutic options for anti-hormonal therapy, the role of anti-hormonal agents in advanced breast cancer, and adjuvant therapy and the current status of chemoprevention with selective ER modulators.

Strategies for the Prevention of Treatment-Related Bone Loss in Women Receiving Adjuvant Hormonal Therapy

More than 220,000 women will be diagnosed with breast cancer this year, and approximately 75% of these women will be long-term survivors of this disease. Survival has improved largely because of advances in adjuvant hormone therapy and chemotherapy, as well as early detection strategies. Because most women will receive adjuvant treatment, and the majority will survive cancer, it is increasingly important to understand the resultant toxicities and to devise monitoring and treatment strategies to avoid adverse long-term effects. Loss of bone mineral density leading to osteoporosis and increased risk of fracture as well as other morbidities is a well known complication of estrogen suppression associated with use of aromatase inhibitors (AIs) in postmenopausal women, and ovarian suppression with GnRH agonists or chemotherapy in premenopausal women. Hormone receptor positivity is increasingly frequent with increasing patient age, so that a large number of women already at risk for osteopenia associated with menopause are at risk for further bone loss caused by adjuvant hormone therapy with AIs. This article will review data on bone mineral density loss and risk of fracture in the large, randomized phase III trials comparing tamoxifen to AIs using the upfront, switching or extended hormone therapy approach. Data from prophylactic bisphosphonate intervention trials in both post- and premenopausal women will be discussed. Ongoing trials are described.

Combined ovarian ablation and aromatase inhibition as first-line therapy for hormone receptor-positive metastatic breast cancer in premenopausal women: report of three cases

Aromatase inhibitors have become well established for the treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer and for adjuvant hormonal therapy for primary breast cancer. Benefit of aromatase inhibition has not yet been extended to premenopausal women. Ovarian ablation by oophorectomy, ovarian radiation or hormonal suppression is the initial recommended treatment for hormone receptor-positive metastatic breast cancer in premenopausal women. The addition of tamoxifen improves the benefit of ovarian ablation/ovarian suppression. Addition of aromatase inhibitors to luteinizing hormone-releasing hormone analogs has been reported to significantly decrease circulating estrogens and produce tumor responses in only a very small number of patients over the last 15 years. We treated three premenopausal patients with hormone receptor-positive metastatic breast cancer with combined oophorectomy or ovarian irradiation and anastrozole. One patient remained free of progression for 4 years, while the other two remained free of progression for more than 5 and 3 years, respectively. We also note that monthly zoledronic acid for 4 years produced sclerosis of vertebral body metastasis. We conclude that combined ovarian ablation and aromatase inhibition is a feasible treatment modality that deserves more attention and further investigation for hormone receptor-positive metastatic breast cancer in premenopausal women.

Inadvertent Use of Aromatase Inhibitors in Patients with Breast Cancer with Residual Ovarian Function: Cases and Lessons

Aromatase inhibitors (AIs) are important adjunctive therapy for postmenopausal women with hormone receptor-positive, early-stage breast cancer. At the present time, AIs have no role for the management of breast cancer in premenopausal women. We report on several cases of the inadvertent use of AI therapy among women with residual ovarian function. A common experience in these cases was the onset of chemotherapy-related amenorrhea before initiation of AI therapy, which confounded assessment of true menopausal status. We believe clinicians should be aware of the potential ovarian reserve among women with treatment-related amenorrhea so as to avoid use of AI therapy in patients in whom there is uncertainty about menopausal status.

Review: aromatase inhibitors for ovulation induction

CONTEXT

For the last 40 yr, the first line of treatment for anovulation in infertile women has been clomiphene citrate (CC). CC is a safe, effective oral agent but is known to have relatively common antiestrogenic endometrial and cervical mucous side effects that could prevent pregnancy in the face of successful ovulation. In addition, there is a significant risk of multiple pregnancy with CC, compared with natural cycles. Because of these problems, we proposed the concept of aromatase inhibition as a new method of ovulation induction that could avoid many of the adverse effects of CC. The objective of this review was to describe the different physiological mechanisms of action for CC and aromatase inhibitors (AIs) and compare studies of efficacy for both agents for ovulation induction.

EVIDENCE ACQUISITION

We conducted a systematic review of all the published studies, both controlled and noncontrolled, comparing CC and AI treatment, either alone or in combination with gonadotropins, for ovulation induction or augmentation, identified through the Entrez-PubMed search engine.

EVIDENCE SYNTHESIS

Because of the recent acceptance of the concept of using AIs for ovulation induction, few controlled studies were identified, and the rest of the studies were pilot or preliminary comparisons. Based on these studies, it appears that AIs are as effective as CC in inducing ovulation, are devoid of any antiestrogenic side effects, result in lower serum estrogen concentrations, and are associated with good pregnancy rates with a lower incidence of multiple pregnancy than CC. When combined with gonadotropins for assisted reproductive technologies, AIs reduce the dose of FSH required for optimal follicle recruitment and improve the response to FSH in poor responders.

CONCLUSIONS

Preliminary evidence suggests that AIs may replace CC in the future because of similar efficacy with a reduced side effect profile. Although worldwide experience with AIs for ovulation induction is increasing, at present, definitive studies in the form of randomized controlled trials comparing CC with AIs are lacking.

Aromatase inhibitors in the adjuvant treatment of postmenopausal women with early stage breast cancer

This article summarizes the current data regarding the use of the aromatase inhibitors as adjuvant hormonal therapy for postmenopausal women with early stage breast cancer. The article focuses on the five major trials examining the use of these drugs and their toxicity in the adjuvant setting. The data currently available suggest that the aromatase inhibitors are efficacious, either as upfront therapy or after a course of tamoxifen. Ongoing trials will compare these approaches and guide the use of these agents in the years to come.