Use of letrozole versus clomiphene citrate combined with gonadotropins in intrauterine insemination cycles: a pilot study

A comparison of oral versus injectable ovarian stimulation in IUI in women ≥38 years of age with decreased ovarian reserve

PURPOSE

To compare pregnancy rates of oral ovarian hyperstimulation agents (clomiphene citrate (CC) and letrozole) versus injectable agents (gonadotropins) in intrauterine insemination (IUI) in the older reproductive age group with diminished ovarian reserve.

METHODS

A retrospective cohort study was performed among 210 women 38-43 years of age undergoing IUI with controlled ovarian hyperstimulation (COH) at a single academic institution between 2009 and 2018.

RESULTS

A total of 335 IUI cycles met inclusion criteria. Gonadotropins were the most frequently used ovarian hyperstimulation agent (n = 264), followed by CC (n = 38) and letrozole (n = 33). Mean age of the cohort was 40.5 (±1.6) years (range 38-43) did not differ significantly among groups (p = 0.41). Mean AFC and number of mature follicles on day of ovulation trigger also did not differ among groups (p = 0.98, p = 0.10). Overall clinical pregnancy rate was 7.5% per cycle, and rates for CC, letrozole, and gonadotropins respectively were 5.3%, 9.1%, 7.5% per cycle (p = 0.347). There was one multiple gestation pregnancy (twins), which was in a patient stimulated with gonadotropins.

CONCLUSION

This is the first study to compare CC, letrozole, and gonadotropins in older reproductive age women with decreased ovarian reserve. The findings reveal that COH/IUI in older women with decreased ovarian reserve is a viable option (clinical pregnancy rate of 7.5% per cycle), and suggest that oral stimulation agents may be the first-line option, with letrozole having conferred the highest clinical pregnancy rate, 9.1%, which is notable given the typical poor fecundability of this population. However, larger population studies are needed to support this.

[Does fertility treatment increase the risk of breast cancer? Current knowledge and meta-analysis]

OBJECTIVE

The objective of this review was to assess the level of risk of breast cancer for women exposed to ovulation-inducing therapy (OIT).

METHODS

The 25 selected studies were extracted from the PUBMED database from January 2000 until March 2016 with the following key-words: "fertility agents", "infertility treatments", "clomiphene citrate", "buserelin", "ovarian stimulation", "assisted reproductive technology" and "breast cancer". Our meta-analysis was performed using Review Manager software, Cochrane Collaboration, 2014. The results were calculated by type of OIT, as well as globally.

RESULTS

The analysis of these published epidemiological studies confirms that exposition to OIT is not a breast cancer risk factor, but the results are contradictory. Two studies have shown a significantly increased risk of breast cancer in a population of infertile women, while two others have found a significant decrease of this risk. The twenty others did not show any impact of IOT over this risk. Our meta-analysis of 20 selected studies has not identified a significant association between exposition to OIT and breast cancer risk (relative risk=0,96; IC 95: (0,81-1,14) for cohort studies and odds ratio=0,94; IC 95% (0,81-1,10) for case-control studies).

CONCLUSION

Exposition to OIT is not an identified risk factor for breast cancer. A message reassuring about a possible risk of OIT-related breast cancer should be given to these women. Exposition to OIT is therefore not an indication of increased breast surveillance.

A Study of Controlled Ovarian Stimulation with Clomiphene Citrate or Letrozole in Combination with Gonadotropins and IUI in Unexplained Infertility

Aim:

To compare the effect of clomiphene citrate (CC) + human menopausal gonadotropin (hMG) with letrozole + hMG on size, number of follicles, endometrial thickness, serum levels of oestradiol and progesterone and pregnancy rate.

Settings and Design:

Non-randomised interventional study.

Patients and Methods:

A total number of 60 patients in the age group of 20–35 years with unexplained infertility were divided into two groups, 30 in each. Group A received CC + hMG and group B received letrozole + hMG. In both the groups, ovulation was triggered by hCG followed by intrauterine insemination.

Results:

The number of follicles on day 8 were significantly higher in the CC + hMG group than that in the letrozole + hMG group. Serum oestradiol level was significantly higher in the CC + hMG group on day 10 and on the day of hCG administration. Pregnancy rate in the CC + hMG group was 23.3% and 13.3% in the letrozole + hMG group.

Conclusion:

The sequential protocol was cost-effective. CC + hMG could be a preferred ovarian stimulation protocol in couples with unexplained infertility with the added advantage of having no significant complications in properly monitored cycles.

Cost effectiveness of letrozole and purified urinary FSH in treating women with clomiphene citrate-resistant polycystic ovarian syndrome: a randomized controlled trial

We aimed to compare the cost effectiveness of letrozole versus purified urinary follicle stimulating hormone (FSH) in treating patients with clomiphene citrate (CC)-resistant polycystic ovary syndrome (PCOS). This was a randomized trial conducted in Cairo University and Beni-Suef University Hospitals, Egypt. A cohort of 140 eligible women was randomized to receive either letrozole 2.5 mg twice daily for five days, or FSH using a graduated regimen starting with a dose of 75 IU. Treatment was repeated for three months if pregnancy did not occur. There were no significant differences between the two treatments in the cumulative clinical pregnancy rate (30% vs. 34%; p = 0.578), cumulative ovulation rate (47% vs. 57%; p = 0.236), miscarriage rate (9% vs. 4%, p > 0.999) or multiple pregnancy rate (0% and 8%, p = 0.491) but the FSH cycles were 4.8 times more expensive. Letrozole and FSH were both effective in treating women with CC-resistant PCOS but letrozole was more cost effective.Study registration number: NCT02304107.

T2 breast cancer presenting with diffuse liver metastases and hepatic failure following fertility treatment. Cautionary report

•

Metastatic breast cancer presenting with liver failure is rare.

•

This case had fertility treatments with clomiphene for an undisclosed duration before presenting with a T2 tumour with diffuse hepatic metastases.

•

The extent of metastases was not consistent with the duration of the t2 tumour of 3months.

•

The rapidity of progression and demise within a week of presentation is remarkable.

•

This would be a cautionary report emphasizing the need for increased screening and surveillance during fertility treatments.

Background

Diffuse hepatic metastases with hepatic failure as a presentation of a T2 breast cancer is rare. This is also remarkable seeing our case had been on fertility treatments before presentation. There are no documented reports of breast cancer patient on fertility treatment presenting with diffuse hepatic metastases and liver failure.

Case summary

A 41 year old Para 1 Nigerian woman being managed for secondary infertility with an extended use of clomiphene presented with a 3 months history of a left breast lump, nipple bleeding and later, yellowness of eyes, right hypochondrial pain malaise and drowsiness. Abdominal USS showed an enlarged liver with diffuse metastatic nodules. Liver function tests showed persistently elevating liver enzymes and serum bilirubin. Serology showed Hepatitis B negative. She was diagnosed with a T2 left invasive ductal carcinoma, Er−, Pr+ Her2+ with deteriorating liver function from diffuse hepatic metastases She had chemotherapy but succumbed barely a week of presentation.

Conclusion

Breast cancer screening for patients before fertility treatments and continual surveillance while on such treatment is highly recommended.

A comparison of the efficacy of two doses of letrozole alone or with continuous recombinant follicle-stimulating hormone for ovulation induction in anovulatory women

AIMS

To determine the efficacy of letrozole alone or with recombinant follicle-stimulating hormone (rFSH) for ovarian induction in anovulatory women.

METHODS

A total of 322 patients undergoing intrauterine insemination (IUI) were included in this retrospective study. Letrozole (2.5 or 5.0 mg) was administered from days 5 to 9 of menses, alone or followed with rFSH started on day 9 until the day of human chorionic gonadotropin administration. A single IUI was performed 24 h after ovulation.

RESULTS

The number of follicles, endometrial thickness and serum estradiol levels were significantly higher in the letrozole + rFSH groups than in the letrozole-alone groups (p < 0.05), but no significant difference was found between the two doses of letrozole, whether alone or with rFSH. Women treated with 5.0 mg/day of letrozole + rFSH required a total dose of rFSH similar to women treated with 2.5 mg/day of letrozole + rFSH (230.77 ± 118.29 vs. 258.55 ± 130.13 IU, respectively; p = 0.205). There was no significant difference in pregnancy rates between the two doses of letrozole, whether alone or with rFSH.

CONCLUSION

Treatment with letrozole + rFSH was more efficacious than letrozole alone for pregnancy in the IUI program; however, the effect of 5.0 mg/day of letrozole versus 2.5 mg/day of letrozole on ovulation was equivalent, regardless of whether rFSH was used.

Letrozole stimulation in endometrial preparation for cryopreserved-thawed embryo transfer in women with polycystic ovarian syndrome: a pilot study

OBJECTIVE

To study the efficiency of letrozole, an aromatase inhibitor, in endometrial preparation for cryopreserved-thawed embryo transfer (FET) in women with polycystic ovarian syndrome (PCOS).

DESIGN

Retrospective observational study.

PATIENTS

One hundred and twenty patients with PCOS who met the inclusion criteria for the study.

MEASUREMENTS

We assessed in vitro fertilization outcomes in one hundred and twenty patients with PCOS (148 cycles) who were prepared for and underwent FET between June 2011 and December 2012. Patients were prepared for FET using artificial hormone cycles induced with oestrogen and progesterone supplementation (n = 76), letrozole stimulation (n = 40) or hMG stimulation (n = 32).

RESULTS

There were no differences in demographic characteristics between the groups, except that the letrozole group had a higher incidence of embryo transfer failure in the past. The letrozole stimulation group had a significantly higher maximal endometrial thickness and significantly higher rates of clinical pregnancy per transfer, ongoing pregnancy per transfer and implantation, compared with the artificial and hMG stimulation groups. Differences in these parameters between the artificial and hMG stimulation groups were not significant.

CONCLUSION

Using letrozole stimulation in endometrial preparation for cryopreserved-thawed embryo transfer in patients with PCOS may be associated with better outcomes than using hormonal manipulation or hMG stimulation.

Sequential clomiphene citrate/hMG versus hMG for ovulation induction in clomiphene citrate-resistant women

OBJECTIVE

This study was designed to compare sequential clomiphene citrate/hMG regimen to hMG regimen for ovulation induction in clomiphene citrate-resistant women.

STUDY DESIGN

A comparative prospective study.

PATIENTS AND METHODS

Ninety infertile women were randomized to receive either sequential CC/hMG regimen (45 women) or low-dose step-up protocol of hMG (45 women). All participants had received at least six consecutive cycles of clomiphene citrate for ovulation induction within the last year before inclusion in this study, but they did not conceive. The CC/hMG regimen group received clomiphene citrate 100 mg/day for 5 days, followed by hMG 75 IU for 4 days. The hMG group received low-dose step-up protocol for 10-14 days. To detect the number and size of the follicles, TVS was done on cycle day 8 and repeated daily or every other day according to follicular development. When one to three follicles reached a diameter ≥18 mm, hCG injection was scheduled. Before hCG injection, the E2 level and endometrial thickness were evaluated. β-hCG levels were measured on cycle day 22.

RESULTS

There was no significant difference between the two studied groups regarding the demographic data, sperm parameters, and day 3 FSH, LH and estradiol. Also, there was no significant difference between the two studied groups regarding endometrial thickness, number of mature follicles, peak of E2 before hCG injection and number of cases that developed ovarian cyst or OHSS. The dose of gonadotropins used was significantly low in the CC/hMG group compared to the hMG group (295.2 ± 75.5 vs. 625.3 ± 65.0, respectively), and the pregnancy rate was significantly high in the CC/hMG group compared to the hMG group [12 (26.7 %) vs. 3 (6.7 %), respectively, p < 0.05].

CONCLUSION

The sequential CC/hMG regimen is as effective as hMG regimen for ovulation induction, produces satisfactory pregnancy results and reduces the treatment cost.

Randomized comparison of superovulation with letrozole vs. clomiphene citrate in an IUI program for women with recently surgically treated minimal to mild endometriosis

OBJECTIVE

To evaluate pregnancy rates with letrozole and clomiphene citrate (CC) alone for superovulation in an intrauterine insemination program for women with recently surgically treated minimal to mild endometriosis.

DESIGN

A randomized controlled trial following the CONSORT criteria.

SETTING

University teaching hospital and a private practice setting.

PATIENTS

136 women with primary infertility due to minimal to mild endometriosis who did not achieve pregnancy after six to 12 months following laparoscopic treatment.

INTERVENTIONS

Superovulation using 5 mg letrozole/day (69 women, 220 cycles) or 100 mg CC/day (67 women, 213 cycles) for five days combined with intrauterine insemination up to four cycles.

MAIN OUTCOME MEASURES

Clinical pregnancy rate per cycle, cumulative pregnancy rate after four cycles, number of follicles, serum estradiol, endometrial thickness on the day of human chorionic gonadotropin administration, serum progesterone, miscarriage and live birth rates.

RESULTS

The clinical pregnancy rate per cycle and the cumulative pregnancy rate after four cycles were comparable (15.9 vs. 14.5% and 64.7 vs. 57.2%; p=0.82, p=0.71 in letrozole and CC groups, respectively). Two twin pregnancies occurred in the CC/intrauterine insemination group. Miscarriage and live birth rates were comparable (11.4 vs. 12.9% and 44.9 vs. 40.3%; p=0.47, p=0.62 in letrozole and CC groups, respectively). The total number of follicles and serum estradiol on the day of human chorionic gonadotropin administration were significantly increased in the CC group.

CONCLUSIONS

Superovulation with letrozole is not more effective than clomiphene citrate alone in an intrauterine insemination program for women with minimal to mild endometriosis who did not achieve pregnancy after six to 12 months following laparoscopic treatment. ClinicalTrials.gov ID: NCT01334762.

Effects of a non-steroidal aromatase inhibitor on ovarian function in cattle

Effects of the non-steroidal aromatase inhibitor letrozole on ovarian function in cattle were determined. The hypothesis that letrozole would arrest growth of the dominant follicle, resulting in emergence of a new follicular wave at a predictable post-treatment interval, was tested. Heifers were assigned randomly to four groups 4 days after follicular ablation (~2½ days after wave emergence) and given intravenous doses of 500 (n = 9), 250 (n = 10), or 125 µg kg–1 (n = 10) letrozole or phosphate-buffered saline (controls; n = 10). Blood was collected and ovarian structures were monitored daily by transrectal ultrasonography. Plasma concentrations of LH and FSH were measured by radioimmunoassay; plasma concentrations of letrozole were determined by high-performance liquid chromatography tandem mass spectrometry. A single intravenous dose of letrozole did not induce regression of the dominant follicle present at the time of treatment, nor did it directly affect FSH release. Conversely, treatment with letrozole increased endogenous concentrations of LH and extended the lifespan of the dominant follicle, which delayed the next FSH surge and subsequent follicular wave emergence. Letrozole continues to have potential as a non-steroidal treatment for controlling ovarian function in cattle.

Effect of infertility treatment and pregnancy-related hormones on breast cell proliferation in vitro

BACKGROUND

Breast cancer development involves a series of mutations in a heterogeneous group of proto-oncogenes/tumor suppressor genes that alter mammary cells to create a microenvironment permissive to tumorigenesis. Exposure to hormones during infertility treatment may have a mutagenic effect on normal mammary epithelial cells, high-risk breast lesions and early-stage breast cancers. Our goal was to understand the association between infertility treatment and normal and cancerous breast cell proliferation.

METHODS

MCF-10A normal mammary cells and the breast cancer cell lines MCF-7 [estrogen receptor (ER)-positive, well differentiated] and HCC 1937 (ER-negative, aggressive, BRCA1 mutation) were treated with the weak ER activator clomiphene citrate and hormones that are increased during infertility treatment. Direct effects of treatment on cell proliferation and colony growth were determined.

RESULTS

While clomiphene citrate had no effect on MCF-10A cells or MCF-7 breast cancer cells, it decreased proliferation of HCC 1937 versus untreated cells (P= 0.003). Estrogen had no effect on either MCF-10A or HCC 1937 cells but, as expected, increased cell proliferation (20-100 nM; P≤0.002) and colony growth (10-30 nM; P< 0.0001) of MCF-7 cells versus control. Conversely, progesterone decreased both proliferation (P= 0.001) and colony growth (P= 0.01) of MCF-10A cells, inhibited colony size of MCF-7 cells (P= 0.01) and decreased proliferation of HCC 1937 cells (P= 0.008) versus control. hCG (100 mIU/ml) decreased both proliferation (P ≤ 0.01) and colony growth (P ≤ 0.002) of all three cell lines.

CONCLUSIONS

Although these data are preclinical, they support possible indirect estrogenic effects of infertility regimens on ER-positive breast cancer cells and validate the potential protective effect of pregnancy-related exposure to hCG.

Aromatase inhibitors for female infertility: a systematic review of the literature

Ovulation induction remains a milestone in the treatment of women with anovulatory infertility. Clomiphene citrate (CC) is considered the first line treatment for induction of ovulation in women with polycystic ovary syndrome (PCOS), while it may be used for ovulation induction in unexplained infertility. Aromatase inhibitors (AI) have been introduced as a new treatment option that could challenge CC for ovulation induction. A systematic review of the literature was conducted in order to highlight the efficacy and safety of AI in female infertility. Current data from randomized and non-randomized trials suggest that AI may have a role in ovulation induction regimens in PCOS patients, as well as for ovarian stimulation, since they achieve comparable clinical pregnancy rates to CC. Furthermore, when combined with gonadotrophins, AI improve the ovarian response of poor responders and reduce the gonadotrophin dose required. However, the current review is based on small trials with a limited number of patients. If solid data from future large adequately powered randomized trials support current evidence regarding efficacy and safety, AI might offer a new treatment choice for infertile women.

Comparison of letrozole with continuous gonadotropins and clomiphene-gonadotropin combination for ovulation induction in 1387 PCOS women after clomiphene citrate failure: a randomized prospective clinical trial

PURPOSE

Letrozole, though reported to be an effective ovulation inducing agent, warrants larger randomized trials. The purpose of this study is to compare the efficacy of letrozole with that of rFSH and clomiphene citrate(CC)/rFSH for ovarian stimulation in IUI cycles.

METHODS

Randomized, prospective, single-blinded clinical trial. 1387 PCOS women after CC failure were randomized into three groups: Group A received letrozole, Group B received CC with two doses rFSH and Group C received continuous rFSH day 2 onwards until hCG injection.

RESULTS

Group A, B and C had an ovulation rate of 79.30%, 56.95% and 89.89% and cycle cancellation rate of 20.70%, 43.05% and 10.11%, respectively. Pregnancy rates in Group A, B and C were 23.39%, 14.35% and 17.92%, while the miscarriage rates were 13.80%, 16.67% and 14.52%, respectively.

CONCLUSION

Letrozole appears to be a suitable ovulation inducing agent in PCOS women with CC failure and is found to be most effective when baseline estradiol level >60 pg/ml.

Use of letrozole in assisted reproduction: a systematic review and meta-analysis

BACKGROUND

Letrozole is the third-generation aromatase inhibitor (AI) most widely used in assisted reproduction. AIs induce ovulation by inhibiting estrogen production; the consequent hypoestrogenic state increases GnRH release and pituitary follicle-stimulating hormone (FSH) synthesis.

METHODS

A systematic search of the literature was performed for both prospective and retrospective studies. Meta-analyses of randomized clinical trials (RCTs) were performed for three comparisons: letrozole versus clomiphene citrate (CC), letrozole + FSH versus FSH in intrauterine insemination (IUI) and letrozole + FSH versus FSH in IVF. In the absence of RCTs, non-randomized studies were pooled.

RESULTS

Nine studies were included in the meta-analysis. Four RCTs compared the overall effect of letrozole with CC in patients with polycystic ovary syndrome. The pooled result was not significant for ovulatory cycles (OR = 1.17; 95% CI 0.66–2.09), or for pregnancy rate per cycle (OR = 1.47; 95% CI 0.73–2.96) or for pregnancy rate per patient (OR = 1.37; 95% CI 0.70–2.71). In three retrospective studies which compared L + FSH with FSH in ovarian stimulation for IUI, the pooled OR was 1.15 (95% CI 0.78−1.71). A final meta-analysis included one RCT and one cohort study that compared letrozole + gonadotrophin versus gonadotrophin alone: the pooled pregnancy rate per patient was not significantly different (OR = 1.40; 95% CI 0.67–2.91).

CONCLUSIONS

Letrozole is as effective as other methods of ovulation induction. Further randomized-controlled studies are warranted to define more clearly the efficacy and safety of letrozole in human reproduction.

RETRACTED: Anastrozole or letrozole for ovulation induction in clomiphene-resistant women with polycystic ovarian syndrome: a prospective randomized trial

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the ASRM Publications Committee. Several reports of randomized clinical trials were recently the subject of an investigation conducted by the publications committee of the ASRM. The committee reviewed concerns related to the validity of data reported in those reports. The committee noted significant duplication of data reported in this manuscript with data reported in another report (PMID: 19732888; https://doi.org/10.1016/j.fertnstert.2009.07.985) pertaining to a different study group that could not be explained. As we cannot vouch for the validity of the data, we have issued a retraction of this paper.

Comparison of the efficacy of the aromatase inhibitor letrozole and clomiphen citrate gonadotropins in controlled ovarian hyperstimulation: a prospective, simply randomized, clinical trial

OBJECTIVE

To study the efficacy of the aromatase inhibitor letrozole in controlled ovarian hyperstimulation (COH).

MATERIAL AND METHODS

In this prospective simply randomized clinical trial, one hundred forty patients with unexplained infertility undergoing intrauterine insemination (IUI) therapy were randomized to receive either letrozole or clomiphene citrate (CC)-gonadotropin. The patients were selected among patients referred to one university hospital and one private infertility clinic. A letrozole dose of 5 mg/day (n = 70) was given on days 3-7 of the menstrual cycles. Clomiphen citrate a dose of 100 mg/day was given like letrozole but combined with human menopausal gonadotropin (hMG) dose of 75 IU/ml administered every day starting on day 6. Ovulation was triggered with urinary hCG (10,000 IU) when the leading follicle(s) reached 18 mm in diameter. A single IUI was performed 36 hours later. The luteal phase was supplemented with micronized progesterone vaginally. Ovarian stimulation response (E2 levels and number of follicles) was primary outcome.

RESULTS

There were no differences in demographic characteristics between groups. The number of mature follicles (1.8 +/- 0.7 vs. 2.46 +/- 2.3; P = 0.042) and serum E2 level on the day of hCG (310 +/- 135.4 vs. 1,670.7 +/- 1021.8 pg/ml, respectively; P < 0.0001) were significantly lower in letrozole group. A significantly higher endometrial thickness was observed at the time of hCG administration in patients that received letrozole (9.7 +/- 1.6 mm vs. 7.8 +/- 2 mm; P < 0.001). Clinical pregnancy rates also were significantly higher in letrozole group (32.8% vs. 14.3%, respectively; P < 0.01).

CONCLUSION

The aromatase inhibitor letrozole appears to constitute a good alternative to CC-gonadotropin in patients with unexplained infertility undergoing COH cycles combined with IUI therapy.

Effect of letrozole at 2.5 mg or 5.0 mg/day on ovarian stimulation with gonadotropins in women undergoing intrauterine insemination

OBJECTIVE

To determine the effect of combined therapy of letrozole (2.5 mg or 5.0 mg) with recombinant follicle-stimulating hormone (FSH) in comparison with the administration of recombinant FSH alone in an intrauterine insemination (IUI) program.

DESIGN

Retrospective study.

SETTING

Assisted fertilization program in a specialized infertility center.

PATIENT(S)

110 women undergoing IUI and gonadotropin therapy.

INTERVENTION(S)

Recombinant FSH alone administered from day 3 or combined with letrozole, 2.5 or 5.0 mg/day, on days 3 to 7, and gonadotropins starting on day 7 of the menstrual cycle. Transvaginal ultrasound examinations were done until the dominant follicle reached 18 mm in diameter. Ovulation was triggered with 10,000 IU of human chorionic gonadotropin (hCG), and IUI performed 30 to 40 hours later.

MAIN OUTCOME MEASURE(S)

Recombinant FSH dose required, number of follicles greater than 14 mm and 18 mm, endometrial thickness, pregnancy rates, miscarriages, and characteristics of newborns.

RESULT(S)

Women treated with FSH and 5.0 mg/day of letrozole required a lower dose of FSH than the group cotreated with 2.5 mg/day of letrozole or with FSH alone. Throughout most of the follicular phase, the endometrial thickness was statistically significantly less in both letrozole cotreatment groups compared with the FSH control group. By the day of hCG administration, the endometrial thickness was comparable among all the groups. The pregnancy rates were the same with recombinant FSH alone or combined with letrozole.

CONCLUSION(S)

In terms of cost-effectiveness, 5.0 mg/day of letrozole is more effective than the 2.5 mg/day in cotreatment with no adverse effect on pregnancy rate or outcome.

Letrozole: present and future role in the treatment of breast cancer

State of the art hormonal therapy for women with breast cancer has evolved over the last few years. Tamoxifen used to be the gold standard for adjuvant treatment of postmenopausal women with hormone-sensitive early breast cancer and also for patients with metastatic disease in whom hormonal manipulation was considered, but the introduction of third generation aromatase inhibitors has changed this concept. This article discusses the clinical implications of recent trials with one of the aromatase inhibitors letrozole, including pharmacokinetic and pharmacodynamic data as well as recent data on relative benefits and side effects compared with other available hormonal agents. Relevant ongoing clinical-translational trials evaluating this agent are also discussed.

RETRACTED: Clomiphene citrate or letrozole for ovulation induction in women with polycystic ovarian syndrome: a prospective randomized trial

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the ASRM Publications Committee Several reports of randomized clinical trials were recently the subject of an investigation conducted by the publications committee of the ASRM. The committee reviewed concerns related to the validity of data reported in those reports. The committee noted significant duplication of data reported in this manuscript with data reported in another journal (PMID 17364286; https://doi.org/10.1080/00016340601090337) and another publication in Fertility and Sterility (PMID: 18692823; https://doi.org/10.1016/j.fertnstert.2008.06.013) pertaining to different study groups that could not be explained. As we cannot vouch for the validity of the data, we have issued a retraction of this paper.

New advances in ovulation induction

PURPOSE OF REVIEW

To review recent advances in ovulation induction.

RECENT FINDINGS

Aromatase inhibitors can replace clomiphene citrate as ovulation-inducing substances. The most widely used aromatase inhibitor for this purpose is letrozole and the optimal dose is 5 mg daily for 5 days. Compared to clomiphene citrate, it is associated with a thicker endometrium and a better pregnancy rate. It is as effective as gonadotropin but yet less expensive. The overall rates of congenital malformation among newborns conceived after infertility treatment with letrozole or clomiphene citrate are similar. When letrozole is combined with gonadotropin, it leads to lower gonadotropin requirements with pregnancy rates comparable to gonadotropin treatment alone. Another promising aromatase inhibitor is anastrazole. Recent evidence suggests that luteinizing hormone activity in human menopausal gonadotropin modifies follicular development so that fewer intermediate-sized follicles develop. Compared to the use of follicular stimulating hormone only, human menopausal gonadotropin is associated with less ovarian hyperstimulation.

SUMMARY

Aromatase inhibitors are alternative drugs to clomiphene or gonadotropin for ovulation induction or superovulation.