Pregnancy during gonadotrophin-releasing hormone agonist therapy

The impact of menopause on bone, zoledronic acid, and implications for breast cancer growth and metastasis

Recent data from the AZURE, ABCSG-12, and ZO-FAST clinical trials have challenged our understanding of the potential anticancer activity of zoledronic acid (ZOL). Although the results of these studies may appear to be conflicting on the surface, a deeper look into commonalities among the patient populations suggest that some host factors (i.e. patient age and endocrine status) may contribute to the anticancer activity of ZOL. Indeed, data from these large clinical trials suggest that the potential anticancer activity of ZOL may be most robust in a low-estrogen environment. However, this may be only part of the story and many questions remain to be answered to fully explain the phenomenon. Does estrogen override the anticancer activity of ZOL seen in postmenopausal women? Are hormones other than estrogen involved that contribute to this effect? Does the role of bone turnover in breast cancer (BC) growth and progression differ in the presence of various estrogen levels? Here, we present a review of the multitude of factors affected by different endocrine environments in women with BC that may influence the potential anticancer activity of ZOL.

Zoledronic acid in the treatment of early-stage breast cancer: is there a final verdict?

Breast cancer, which preferentially metastasizes to bone, is the most common malignancy among women worldwide and is a leading cause of death. Clinical data from large, phase 3 trials (ie, ABCSG-12, ZO-FAST, and AZURE) demonstrate significantly improved disease-free survival with zoledronic acid in some patient populations with early breast cancer. Although the interim results from the AZURE trial did not show a disease-free survival benefit with zoledronic acid in the overall patient population, subset analyses showed that zoledronic acid significantly improved disease-free survival in women with established postmenopausal status at baseline. Similarly, subset analyses of the ABCSG-12 trial showed greater benefits from zoledronic acid in patients over 40 years of age who theoretically would have achieved more complete ovarian suppression. Together, these data support a potential role for zoledronic acid beyond bone health in breast cancer and suggest that the endocrine environment may influence the anticancer potential of zoledronic acid.

Bisphosphonates: prevention of bone metastases in breast cancer

Disease recurrence and distant metastases remain challenging for patients with breast cancer despite advances in early diagnosis, surgical expertise, and adjuvant therapy. Bone is the most common site for breast cancer metastasis, and the bone microenvironment plays a crucial role in harboring disseminated tumor cells (DTCs), a putative source of late relapse in and outside bone. Therefore, agents that affect bone metabolism might not only prevent the development of bone lesions but also provide meaningful reductions in the risk of relapse both in bone and beyond. Bisphosphonates bind to mineralized bone surfaces and are ingested by osteoclasts, wherein they inhibit osteolysis, thereby preventing the release of growth factors from the bone matrix. Therefore, the bone microenvironment becomes less conducive to survival and growth of DTCs and bone lesion formation. Recent trials of zoledronic acid in the adjuvant setting in breast cancer have demonstrated reduced disease recurrence in bone and other sites in premenopausal and postmenopausal women with early breast cancer. Based on the proven effect of bone protection during adjuvant endocrine therapy, new treatment guidelines recommend the routine use of bisphosphonates to prevent bone loss during adjuvant therapy, which may likely become the standard practice.

Zoledronic acid in breast cancer: latest findings and interpretations

The intravenous nitrogen-containing bisphosphonate zoledronic acid has been shown to block multiple steps in tumor metastasis (e.g. angiogenesis, invasion, adhesion, proliferation) in preclinical and translational studies. Moreover, clinical data from the ABCSG-12 and ZO-FAST trials demonstrate significantly improved disease-free survival with zoledronic acid in the adjuvant breast cancer setting. In contrast to these two trials, recent interim results from the AZURE trial do not show a benefit from adding zoledronic acid to adjuvant therapy in the overall patient population. However, subset analyses of AZURE data show that zoledronic acid significantly improved overall survival in women who were more than 5 years postmenopausal or older than 60 years at baseline. Similarly, subset analyses of the ABCSG-12 trial data demonstrate greater benefits from zoledronic acid treatment in patients who theoretically would have achieved more complete ovarian suppression. These observations, together with the AZURE postmenopausal data, suggest that the endocrine environment may affect the potential anticancer activity of zoledronic acid. Indeed, current data support the possibility that zoledronic acid might be most effective for improving disease-free survival in the adjuvant breast cancer setting in women who are postmenopausal or have endocrine therapy-induced menopause.

Adjuvant endocrine therapy plus zoledronic acid in premenopausal women with early-stage breast cancer: 62-month follow-up from the ABCSG-12 randomised trial

BACKGROUND

Analysis of the Austrian Breast and Colorectal Cancer Study Group trial-12 (ABCSG-12) at 48 months' follow-up showed that addition of zoledronic acid to adjuvant endocrine therapy significantly improved disease-free survival. We have now assessed long-term clinical efficacy including disease-free survival and disease outcomes in patients receiving anastrozole or tamoxifen with or without zoledronic acid.

METHODS

ABSCG-12 is a randomised, controlled, open-label, two-by-two factorial, multicentre trial in 1803 premenopausal women with endocrine-receptor-positive early-stage (stage I-II) breast cancer receiving goserelin (3.6 mg every 28 days), comparing the efficacy and safety of anastrozole (1 mg per day) or tamoxifen (20 mg per day) with or without zoledronic acid (4 mg every 6 months) for 3 years. Randomisation (1:1:1:1 ratio) was computerised and based on the Pocock and Simon minimisation method to balance the four treatment arms across eight prognostic variables (age, neoadjuvant chemotherapy, pathological tumour stage; lymph-node involvement, type of surgery or locoregional therapy, complete axillary dissection, intraoperative radiation therapy, and geographical region). Treatment allocation was not masked. The primary endpoint was disease-free survival (defined as disease recurrence or death) and analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00295646; follow-up is ongoing.

FINDINGS

At a median follow-up of 62 months (range 0-114.4 months), more than 2 years after treatment completion, 186 disease-free survival events had been reported (53 events in 450 patients on tamoxifen alone, 57 in 453 patients on anastrozole alone, 36 in 450 patients on tamoxifen plus zoledronic acid, and 40 in 450 patients on anastrozole plus zoledronic acid). Zoledronic acid reduced risk of disease-free survival events overall (HR 0.68, 95% CI 0.51-0.91; p=0.009), although the difference was not significant in the tamoxifen (HR 0.67, 95% CI 0.44-1.03; p=0.067) and anastrozole arms (HR 0.68, 95% CI 0.45-1.02; p=0.061) assessed separately. Zoledronic acid did not significantly affect risk of death (30 deaths with zoledronic acid vs 43 deaths without; HR 0.67, 95% CI 0.41-1.07; p=0.09). There was no difference in disease-free survival between patients on tamoxifen alone versus anastrozole alone (HR 1.08, 95% CI 0.81-1.44; p=0.591), but overall survival was worse with anastrozole than with tamoxifen (46 vs 27 deaths; HR 1.75, 95% CI 1.08-2.83; p=0.02). Treatments were generally well tolerated, with no reports of renal failure or osteonecrosis of the jaw. Bone pain was reported in 601 patients (33%; 349 patients on zoledronic acid vs 252 not on the drug), fatigue in 361 (20%; 192 vs 169), headache in 280 (16%; 147 vs 133), and arthralgia in 266 (15%; 145 vs 121).

INTERPRETATION

Addition of zoledronic acid improved disease-free survival in the patients taking anastrozole or tamoxifen. There was no difference in disease-free survival between patients receiving anastrozole and tamoxifen overall, but those on anastrozole alone had inferior overall survival. These data show persistent benefits with zoledronic acid and support its addition to adjuvant endocrine therapy in premenopausal patients with early-stage breast cancer.

FUNDING

AstraZeneca; Novartis.

Should we still advise infertile couples to use (barrier) contraception before IVF down-regulation?

OBJECTIVE

To determine the outcome of spontaneous conceptions in women who received GnRH agonists during mid-luteal phase down-regulation before IVF treatment.

DESIGN

Retrospective analysis of case records and study of the literature.

SETTING

Two university-affiliated reproductive medicine units.

PATIENT(S)

Seventy-three women who conceived spontaneously after starting down-regulation with a GnRH agonist before controlled ovarian hyperstimulation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Course and clinical outcome of pregnancies.

RESULT(S)

Seventy-four pregnancies occurred in 73 women who received a GnRH agonist. Of these patients, 6 (8%) had a biochemical pregnancy, 6 (8%) had an ectopic pregnancy, 21 (28%) miscarried, and 41 pregnancies resulted in successfully delivered babies; there were 2 cases of congenital abnormalities.

CONCLUSION(S)

These cases, together with other published data, suggest that pregnancy outcome is not adversely affected by exposure to GnRH agonist during luteal-phase down-regulation. A central register of pregnant women who received a GnRH agonist is needed.

Pregnancy in a breast cancer patient treated with a LHRH analogue at ablative doses

A 36-year-old female diagnosed of breast cancer was treated with surgery, chemotherapy, radiotherapy and goserelin. After 17 months of uninterrupted therapy with this LHRH analogue at hormone suppressive doses, a 16-week gestation foetus was detected and the treatment was withdrawn. Although the drug was administered throughout the first 4 months of pregnancy it resulted in the term delivery of a healthy infant, and no foetal adverse effects were detected. A review of the influence of hormonal treatment for breast cancer on fertility and birth defects has been performed.