Long-term relationship of ovulation-stimulating drugs to breast cancer risk

Fertility drugs and cancer: a guideline

Methodological limitations in studying the association between the use of fertility drugs and cancer include the inherent increased risk of cancer in women who never conceive, the increased risk of cancer because of factors (endometriosis and unopposed estrogen) associated with infertility, the low incidence of most of these cancers, and that the diagnosis of cancer is typically several years after fertility drug use. On the basis of available data, there does not appear to be an association between fertility drugs and breast, colon, or cervical cancer. There is no conclusive evidence that fertility drugs increase the risk of uterine cancer, although women with infertility are at higher risk of uterine cancer. There are insufficient data to comment on the risk of melanoma and non-Hodgkin lymphoma associated with fertility drug use. Women should be informed that there may be an increased risk of invasive and borderline ovarian cancers and thyroid cancer associated with fertility treatment. It is difficult to determine whether this risk is related to underlying endometriosis, female infertility, or nulliparity.

The association between endometriosis and risk of endometrial cancer and breast cancer: a meta-analysis

PURPOSE

Endometriosis (EMS) is confirmed pathophysiologically to be an estrogen-dependent disease, similar to endometrial hyperplasia/cancer and breast cancer. Epidemiological and biological data on endometriosis might explain links between endometriosis and these cancers. We sought to identify the differences in the risk of endometrial cancer and breast cancer between women with and women without endometriosis.

METHODS

We searched PubMed, EMBASE, the Cochrane Library, and four Chinese databases (CNKI, VIP, WanFang, CBM) to identify relevant studies published online between January 2011 and March 2021. In our meta-analysis, we used the Newcastle-Ottawa Scale (NOS) to evaluate the design and quality of all studies, and we calculated the pooled risk ratio (RR) using the random model. The Q test and I2 were used to evaluate the degree of heterogeneity of eligible studies. We used funnel plots and Begg's and Egger's tests to assess publication bias.

RESULTS

Of the 1369 articles, we finally included 14 cohort studies and seven case-control studies. Data from large cohort and case-control studies indicate that women with endometriosis had an increased risk of both endometrial cancer [RR, 1.662; 95% CI, (1.148-2.407)] and breast cancer [RR, 1.082; 95% CI, (1.001-1.169)].

CONCLUSION

Endometriosis can increase the risk of endometrial cancer and breast cancer, and women with endometriosis are recommended to receive routine screening in long-term management.

OUP accepted manuscript

Background

The significance of exogenous hormone manipulation as part of fertility treatment and its relationship to the development of breast cancer remains uncertain. Several historical reviews have been performed with conflicting results. This study is an updated meta-analysis to determine whether there is a causal relationship between different fertility treatments and breast cancer.

Methods

The study report is based on the guidelines of PRISMA and Meta-Analysis of Observational Studies in Epidemiology. Studies published within the last 20 years were included to reflect up to date in vitro fertilization (IVF) practice. This study was prospectively registered on PROSPERO on 07/04/2021, registration identification CRD42021247706. The primary outcome of the study was to determine whether there is an increased incidence of breast cancer in women treated with hormonal fertility treatment. The secondary outcomes were to determine whether fertility treatments were individually associated with excess breast-cancer risk.

Results

Overall, 25 studies, including 617 479 participants, were eligible for inclusion. There was no significant breast-cancer risk association with fertility treatment (compared with general and subfertility reference groups). Summary odds ratio of all included studies was 0.97 (95 per cent c.i. 0.90 to 1.04). Women who received six or more IVF cycles did not have an increased risk of breast cancer. Similarly, there was no excess breast-cancer risk associated with clomiphene, human chorionic gonadotropin, gonadotropin analogues and progesterone when examined individually. Comparably, there was no significant association between fertility treatment and excess breast-cancer risk in patients with more than 10 years’ follow-up. Summary odds ratio was 0.97 (95 per cent c.i. 0.85 to 1.12).

Conclusion

This meta-analysis did not find a significant association between fertility treatments and excess breast-cancer risk. Women considering IVF should be informed that it does not appear to increase breast-cancer risk.

Association between fertility treatments and breast cancer risk in women with a family history or BRCA mutations: a systematic review and meta-analysis

Women with hereditary breast cancer factors are more likely to be infertile and tend to receive fertility treatments. The safety of fertility treatments that contain hormone-related medications for ovarian stimulation has gained wide attention; however, evidence of the safety of fertility treatments is limited. This study aims to assess the association between fertility treatments and the incidence rate of breast cancer in women with a family history of breast cancer or BRCA mutations. A literature search was conducted in PubMed, Cochrane Library, and Embase. Studies concerning the effect of fertility treatments on breast cancer risk in genetically susceptible women were included. The fixed and random effects models were used to estimate the summary effects. Risk Of Bias In Non-randomized Studies - of Interventions instrument was used to assess the risk of bias in the included studies. A total of 5,282 studies were screened. Five cohort studies and three case-control studies were included. Breast cancer risk was not significantly increased by fertility treatments in general genetically susceptible women [pooled odds ratio (OR) 1.18, 95% confidence interval (CI) 0.96-1.45], women with a family history of breast cancer (pooled OR 1.35, 95% CI 0.97-1.89), or women with BRCA mutations (pooled OR 1.02, 95% CI 0.74-1.4). In subgroup analyses, there was no significant increase in breast cancer risk whether in BRCA1 mutation carriers (pooled OR 1.18, 95% CI 0.81-1.72), BRCA2 mutation carriers (pooled OR 0.54, 95% CI 0.09-3.34), or in the women treated with in vitro fertilization (pooled OR 0.75, 95% CI 0.51-1.1), clomiphene citrate (pooled OR 1.07, 95% CI 0.78-1.45) or gonadotropins (pooled OR 1.32, 95% CI 0.8-2.18). This is the first meta-analysis concerning the impact of fertility treatments on breast cancer risk in genetically susceptible women. Despite the finding that fertility treatment did not significantly increase breast cancer risk in genetically susceptible women, large prospective cohorts with more detailed information are required. Further investigations are needed to explore subtypes of breast cancer, genetic background of hormone-related breast cancer, and the association between BRCA mutations and the incidence of hormone receptor-positive breast cancer.

REGISTRATION NUMBER

PROSPERO(CRD42021281336).

The Impact of Exogenous Estrogen Exposure on the Characteristics and Outcome of Estrogen Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Early-Stage Breast Cancer

INTRODUCTION

The impact of exogenous estrogen exposure on breast cancer characteristics and outcomes is not well described. We aimed to investigate the effect of prior treatment with oral contraceptives (OCT), hormone replacement therapy (HRT), and fertility treatments on early-stage, estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer.

METHODS

This is a single-center retrospective cohort study comprising all women with ER-positive, HER2-negative, early breast cancer whose tumors were sent to Oncotype DX analysis between 2005 and 2012. Data on prior exposures to OCT, HRT, and fertility treatments were collected. The impact of these exposures on prespecified histopathological features was assessed including tumor size, nodal status, intensity of the hormonal receptors, grade, Oncotype recurrence score, Ki67, and lymphovascular and perineural invasion. The impact of these exposures on disease-free survival (DFS) and overall survival (OS) was also evaluated.

RESULTS

A total of 620 women were included, of which 19% had prior exposure to OCT, 30% to HRT, and 11% to fertility treatments. OCT use was associated with smaller (≤1 cm) tumors (p = 0.023) and were less likely to have grade 3 disease (p = 0.049). No other associations were found between exogenous estrogen exposure and tumor characteristics. Median follow-up was 10.4 years. Ten-year DFS was 85.7%, and it was not influenced by exogenous exposure. Ten-year OS was 90.2%, and OCT was associated with improved OS in univariate analysis (HR = 0.31, 95% CI: 0.11-0.85), but this difference did not remain significant in multivariate analysis (p = 0.275).

CONCLUSION

The impact of exogenous estrogen exposure on ER-positive, HER2-negative early breast cancer characteristics is limited. In the long term, none of the evaluated exposures had negative effect on DFS and OS.

Risk of breast cancer in women treated with ovarian stimulation drugs for infertility: a systematic review and meta-analysis

OBJECTIVE

To evaluate the evidence addressing the association between the use of ovarian stimulation drugs and the risk of breast cancer.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Women without any previous history of breast cancer undergoing ovarian stimulation.

INTERVENTION(S)

Electronic databases were searched from 1990 until January 2020. All cohort studies reporting new incidences of breast cancer in infertile women using ovarian stimulating drugs were included. Treated (exposed) infertile women were compared with the unexposed general population with unexposed infertile women as controls.

MAIN OUTCOME MEASURE(S)

New diagnosis of breast cancer within an infertile and general population after exposure to ovarian stimulation drugs.

RESULT(S)

Overall, the quality of evidence was very low because of the serious risk of bias and indirectness (nonrandomized studies). There was no significant increase in the risk of breast cancer among women treated with any ovarian stimulation drug for infertility compared with that in unexposed controls from the general population and the infertile population (pooled odds ratio 1.03, 95% Confidence interval 0.86 to 1.23, 20 studies, I² = 88.41%, very low quality of evidence). Furthermore, no significant increase in the risk of breast cancer was found with the use of clomiphene citrate or gonadotropins, alone or in combination.

CONCLUSION(S)

The current study found that the use of clomiphene citrate and gonadotropins in infertile women was not associated with an increased risk of breast cancer.

Fertility treatment and cancers-the eternal conundrum: a systematic review and meta-analysis

STUDY QUESTION

Does fertility treatment (FT) significantly increase the incidence of breast, ovarian, endometrial or cervical cancer?

SUMMARY ANSWER

Overall, FT does not significantly increase the incidence of breast, ovarian or endometrial cancer and may even reduce the incidence of cervical cancer.

WHAT IS KNOWN ALREADY

Infertility affects more than 14% of couples. Infertility and nulliparity are established risk factors for endometrial, ovarian and breast cancer, yet the association with FT is more contentious.

STUDY DESIGN, SIZE, DURATION

A literature search was carried out using Cochrane Library, EMBASE, Medline and Google Scholar up to December 2019. Peer-reviewed studies stating cancer incidence (breast, ovarian, endometrial or cervical) in FT and no-FT groups were identified. Out of 128 studies identified, 29 retrospective studies fulfilled the criteria and were included (n = 21 070 337).

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the final meta-analysis, 29 studies were included: breast (n = 19), ovarian (n = 19), endometrial (n = 15) and cervical (n = 13), 17 studies involved multiple cancer types and so were included in each individual cancer meta-analysis. Primary outcome of interest was cancer incidence (breast, ovarian, endometrial and cervical) in FT and no-FT groups. Secondary outcome was cancer incidence according to specific fertility drug exposure. Odds ratio (OR) and random effects model were used to demonstrate treatment effect and calculate pooled treatment effect, respectively. A meta-regression and eight sub-group analyses were performed to assess the impact of the following variables, maternal age, infertility, study size, outliers and specific FT sub-types, on cancer incidence.

MAIN RESULTS AND THE ROLE OF CHANCE

Cervical cancer incidence was significantly lower in the FT group compared with the no-FT group: OR 0.68 (95% CI 0.46-0.99). The incidences of breast (OR 0.86; 95% CI 0.73-1.01) and endometrial (OR 1.28; 95% CI 0.92-1.79) cancers were not found to be significantly different between the FT and no-FT groups. Whilst overall ovarian cancer incidence was not significantly different between the FT and no-FT groups (OR 1.19; 95% CI 0.98-1.46), separate analysis of borderline ovarian tumours (BOT) revealed a significant association (OR 1.69; 95% CI 1.27-2.25). In further sub-group analyses, ovarian cancer incidence was shown to be significantly higher in the IVF (OR 1.32; 95% CI 1.03-1.69) and clomiphene citrate (CC) treatment group (OR 1.40; 95% CI 1.10-1.77), respectively when compared with the no-FT group. Conversely, the incidences of breast (OR 0.75; 95% CI 0.61-0.92) and cervical cancer (OR 0.58; 95% CI 0.38-0.89) were significantly lower in the IVF treatment sub-group compared to the no-FT group.

LIMITATIONS, REASONS FOR CAUTION

The large, varied dataset spanning a wide study period introduced significant clinical heterogeneity. Thus, results have to be interpreted with an element of caution. Exclusion of non-English citations, unpublished work and abstracts, in order to ensure data accuracy and reliability was maintained, may have introduced a degree of selection bias.

WIDER IMPLICATIONS OF THE FINDINGS

The results for breast, ovarian, endometrial and cervical cancer are reassuring, in line with previously published meta-analyses for individual cancers but the association between IVF and CC treatment and an increase in ovarian cancer incidence requires additional work to understand the potential mechanism driving this association. In particular, focusing on (i) discriminating specific treatments effects from an inherent risk of malignancy; (ii) differential risk profiles among specific patient sub-groups (refractory treatment and obesity); and (iii) understanding the impact of FT outcomes on cancer incidence.

STUDY FUNDING/COMPETING INTEREST(S)

This study did not receive any funding. The authors have no financial, personal, intellectual and professional conflicts of interest to declare.

PROSPERO REGISTRATION NUMBER

CRD42019153404.

Cost effectiveness of in vitro fertilisation and preimplantation genetic testing to prevent transmission of BRCA1/2 mutations

STUDY QUESTION

Is it cost-effective to use in vitro fertilisation and preimplantation genetic testing of monogenic defects (IVT/PGT-M) to prevent transmission of BRCA1/2 mutations to second-generation new births in comparison with naturally conceived births?

SUMMARY ANSWER

In this cost-effectiveness analysis, we found that IVF/PGT-M is cost-effective for BRCA1 and BRCA2 mutation carriers if using a willingness to pay of $50 000 per quality-adjusted life-year (QALY).

WHAT IS KNOWN ALREADY

Carriers of a BRCA1 or BRCA2 mutation have a significantly increased risk of several types of cancer throughout their lifetime. The cost of risk reduction, screening and treatment of cancer in this population is high. In addition, there is a 50% chance of passing on this genetic mutation to each child. One option to avoid transmission of an inherited deleterious gene to one's offspring involves in vitro fertilisation with preimplantation genetic testing.

STUDY DESIGN, SIZE, DURATION

We implemented a state transition model comparing the healthcare impact of a cohort of healthy children born after IVF/PGT-M, who have a population risk of developing cancer, to a cohort of naturally conceived live-births, half of whom are carriers of the BRCA mutation. Transition probabilities are based on published sources, a lifetime horizon and a perspective of a provincial Ministry of Health in Canada.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The target population is the second-generation new births who have at least one parent with a known BRCA1 or BRCA2 mutation.

MAIN RESULTS AND THE ROLE OF CHANCE

At a willingness-to-pay threshold of $50 000 per QALY, IVF/PGT-M is a cost-effective intervention for carriers of either BRCA mutation. For BRCA1, the incremental cost-effectiveness ratio (ICER) for IVF/PGT-M is $14 242/QALY. For BRCA2, the ICER of intervention is $12 893/QALY. Probabilistic sensitivity analysis results show that IVF/PGT-M has a 98.4 and 97.3% chance of being cost-effective for BRCA1 and BRCA2 mutation carriers, respectively, at the $50 000/QALY threshold.

LIMITATIONS, REASONS FOR CAUTION

Our model did not include the short-term negative effect of IVF/PGT-M on the woman's quality of life; in addition, our model did not consider any ethical issues related to post-implantation genetic testing.

WIDER IMPLICATIONS OF THE FINDINGS

In countries in which the healthcare of a large segment of the population is covered by a single payer system such as the government, it would be cost-effective for that payer to cover the cost of IVF/PGT-M for couples in which one member has a BRCA mutation, in order to avoid the future costs and disutility of managing offspring with an inherited BRCA mutation.

STUDY FUNDING/COMPETING INTEREST(S)

Dr Wong's research program was supported by the Canadian Institutes of Health Research (CIHR), the Natural Sciences and Engineering Research Council (NSERC), the Canadian Liver Foundation and an Ontario Ministry of Research, Innovation and Science Early Researcher Award. All authors declared no conflict of interests.

Endometriosis and cancer: a systematic review and meta-analysis

BACKGROUND

Endometriosis is an often chronic, inflammatory gynaecologic condition affecting 190 million women worldwide. Studies have reported an elevated cancer risk among patients with endometriosis. However, prior research has included methodologic issues that impede valid and robust interpretation.

OBJECTIVE AND RATIONALE

We conducted a meta-analysis of studies investigating the association between endometriosis and cancer risk and analysed the results by methodologic characteristics. We discuss the implications of cancer screening in patients and management challenges faced by clinicians.

SEARCH METHODS

We searched PubMed and Embase databases for eligible studies from inception through 24 October 2019. We included cohort and case-control studies examining the association between endometriosis and cancer risk; cross-sectional studies and case reports were excluded. Publications had to present risk/rate/odds estimates with 95% CI. Random effects meta-analysis was used to estimate summary relative risks (SRR) and CIs. Heterogeneity across studies was assessed by the Q test and I2 statistics, and publication bias using Egger's and Begg's tests. Risk of bias and quality of the included studies were assessed using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool.

OUTCOMES

Forty-nine population-based case-control and cohort studies were included. Twenty-six studies were scored as having a 'serious'/'critical' risk of bias, and the remaining 23 'low'/'moderate'. Cancer-specific analyses showed a positive association between endometriosis and ovarian cancer risk (SRR = 1.93, 95% CI = 1.68-2.22; n = 24 studies) that was strongest for clear cell (SRR = 3.44, 95% CI = 2.82-4.42; n = 5 studies) and endometrioid (SRR = 2.33, 95% CI = 1.82-2.98; n = 5 studies) histotypes (Pheterogeneity < 0.0001), although with significant evidence of both heterogeneity across studies and publication bias (Egger's and Begg's P-values < 0.01). A robust association was observed between endometriosis and thyroid cancer (SRR = 1.39, 95% CI =1.24-1.57; n = 5 studies), a very small association with breast cancer (SRR = 1.04, 95% CI =1.00-1.09; n = 20 studies) and no association with colorectal cancer (SRR = 1.00, 95% CI =0.87-1.16; n = 5 studies). The association with endometrial cancer was not statistically significant (SRR = 1.23, 95% CI =0.97-1.57; n = 17 studies) overall and wholly null when restricted to prospective cohort studies (SRR = 0.99, 95% CI =0.72-1.37; n = 5 studies). The association with cutaneous melanoma was also non-significant (SRR = 1.17, 95% CI =0.97-1.41; n = 7 studies) but increased in magnitude and was statistically significant when restricted to studies with low/moderate risk of bias (SRR = 1.71, 95% CI = 1.24-2.36, n = 2 studies). The most robust finding both in terms of statistical significance and magnitude of effect was an inverse association with cervical cancer (SRR = 0.68, 95% CI =0.56-0.82; n = 4 studies); however, this result has a high potential to reflect heightened access to detection of dysplasia for women who reached an endometriosis diagnosis and is thus likely not causal. Several additional cancer types were explored based on <4 studies.

WIDER IMPLICATIONS

Endometriosis was associated with a higher risk of ovarian and thyroid, and minimally (only 4% greater risk) with breast cancer, and with a lower risk of cervical cancer. However, this meta-analysis confirms that: a majority of studies had severe/critical risk of bias; there is impactful heterogeneity across studies-and for ovarian cancer, publication bias; and causal inference requires temporality, which in many studies was not considered. We discuss the implications of these potential associations from the perspectives of patients with endometriosis, clinicians involved in their care, and scientists investigating their long-term health risks.

Executive Summary of the Early-Onset Breast Cancer Evidence Review Conference

The Centers for Disease Control and Prevention launched the Bring Your Brave campaign to increase knowledge about early-onset breast cancer, defined as breast cancer in women aged 18-45 years. The American College of Obstetricians and Gynecologists convened a panel of experts in breast disease from the Society for Academic Specialists in General Obstetrics and Gynecology to review relevant literature, validated tools, best practices, and practice guidelines as a first step toward developing educational materials for women's health care providers about early-onset breast cancer. Panel members conducted structured literature reviews, which were then reviewed by other panel members and discussed at an in-person meeting of stakeholder professional and patient advocacy organizations in April 2019. This article summarizes the relevant literature, existing guidance, and validated tools to guide health care providers in the prevention, early detection, and special considerations of early-onset breast cancer. Substantive knowledge gaps were noted and summarized to provide guidance for future research.

A Cohort Study of Breast Cancer Risk after 20 Years of Follow-Up of Women Treated with Fertility Drugs

BACKGROUND

Using a nationwide cohort of Danish women, we investigated the association between use of fertility drugs and risk of breast cancer.

METHODS

The study cohort included women ages 20 to 44 years and living in Denmark between January 1, 1995 and December 31, 2011. Information on fertility status, use of fertility drugs, breast cancer, covariates, and vital status was obtained from the Danish Infertility Cohort and various Danish national registers. Cox proportional hazard regression models were applied to estimate hazard ratios (HR) and 95% confidence intervals (CI), adjusted for potential confounders.

RESULTS

Of the 1,330,852 women included, 96,782 (7.3%) were infertile, and 20,567 (1.5%) were diagnosed with breast cancer during a median follow-up of 20.9 years. Compared with fertile women, infertile women who had used any fertility drugs did not have an increased hazard for breast cancer overall (HR = 1.02; 95% CI, 0.95-1.10), or for any of the histologic types (ductal, lobular, or mucinous) of breast cancer. Furthermore, no associations were observed between use of specific types of fertility drugs and breast cancer.

CONCLUSIONS

No convincing associations between use of fertility drugs and breast cancer were observed after two decades of follow-up.

IMPACT

Our results do not support a marked association between fertility drugs and breast cancer and are therefore reassuring for infertile women treated with fertility drugs.

Do the Fertility Drugs Increase the Risk of Cancer? A Review Study

Aim: All over the world, many couples cannot conceive a child and have problems with pregnancy. Ovulation-inducing drugs are among the most important drugs used for the treatment of infertility. In recent years, there have been many debates about the relationship between fertility medication and cancer. Due to the lack of comprehensive study of this matter, and as understanding the relationship between the use of fertility drugs and cancer is of importance, the present study was conducted to investigate the relationship between infertility drugs and cancer in women. Materials and Methods: To determine the relationship between infertility treatment and cancer, a comprehensive search was carried out in databases such as; Medline, Web of Science Core Collection, and Scopus using keywords words; "infertility," "ovulation induction," "cancer," "infertility treatment," "ART," "tumor," "controlled ovarian stimulation," "fertility agents," and "neoplasms." Full-text, English language, and original articles were included in this study. Results: In total, 81 articles were entered into the study. The relationship between fertility medications and breast, ovary, endometrial, uterus, colon, thyroid, skin, cervical, and non-Hodgkin's lymphoma cancers were studied. Although the relationship between fertility medications and cancer is theoretically justifiable, most studies have shown that risk of cancer will not increase after fertility treatment. Conclusion: The results of this study did not show that fertility medications increase the risk of cancer among users. In summary, the relationship between infertility treatment and cancer incidence remains an open question.

Mortality in Women Treated With Assisted Reproductive Technology-Addressing the Healthy Patient Effect

In previous studies, investigators have reported reduced mortality among women undergoing assisted reproductive technology (ART) treatment, possibly related to selection of healthy women into ART treatment. Our aim in this study was to explore the impact of relevant selection factors on the association between ART treatment and mortality and to explore effect modification by parity. Women treated with ART in fertility clinics in Denmark during 1994-2009 (n = 42,897) were age-matched with untreated women from the background population (n = 204,514) and followed until December 31, 2010. With adjustment for relevant confounders, the risk of death was lower among ART-treated women during the first 2 years after ART treatment (hazard ratio (HR) = 0.68, 95% confidence interval (CI): 0.63, 0.74), but there was no apparent difference after 10 years (HR = 0.92, 95% CI: 0.79, 1.07). Having children prior to ART treatment was associated with markedly reduced mortality (HR = 0.45, 95% CI: 0.38, 0.53), possibly due to better health among fertile women. While the frequencies of previous medical and psychiatric diagnoses among ART-treated and untreated women were similar, differences in disease severity could explain the reduced mortality among ART-treated women, as poor prognosis would make initiation of ART treatment unlikely. The survival advantage among ART-treated women is likely a selection phenomenon rather than a biological phenomenon.

Use of fertility medications and cancer risk: a review and update

PURPOSE OF REVIEW

There is increasing use of fertility medications for ovulation induction and ovarian stimulation for in-vitro fertilization in the treatment of female infertility. In this review, recent literature regarding the association between fertility medication and cancer risk is reviewed.

RECENT FINDINGS

Several important publications have recently addressed the relationship between use of fertility medications and cancer risk. There are methodological limitations to many of these studies, including unique challenges in studying rare cancers that often develop several years after the time of fertility medication exposure. Although infertility per se is a risk factor for some female cancers, including breast, endometrial and ovarian cancer, most studies do not show a significant risk of these cancers with the use of fertility medications. Some studies, however, have shown a possible increased relative risk of borderline ovarian cancer, although the increased absolute risk is small without a clear causal relationship.

SUMMARY

The collective data regarding the risk of developing cancer from use of fertility medications are reassuring, although several methodological issues in these studies limit definitive conclusions.

Long-term breast cancer risk following ovarian stimulation in young egg donors: a call for follow-up, research and informed consent

In the USA and other countries, oocyte donation is gaining increasing importance. Although sufficient data exist on procedure-associated short-term risks for oocyte donors, such as ovarian hyperstimulation syndrome, long-term follow-up studies of egg donors are lacking and their health risks are unknown. The lack of information may be misleadingly interpreted as lack of risk. Long-term hormone replacement therapy is recognized as a risk factor for breast cancer; the breast cancer risk of ovarian stimulation for egg donors is unknown but is a possibility. This commentary describes five individual cases of egg donors who developed breast cancer (four out of five women in their 30s) despite negative genetic testing results. Additionally, we summarize available studies of breast cancer in infertile women who experienced IVF. We emphasize the need to create egg donor registries that will facilitate long-term studies on egg donors. Until this information is available, we call for more realistic explanations to egg donors about the lack of knowledge of long-term risks as well as more transparent informed consent documents.

Safety of clomiphene citrate: a literature review

Clomiphene citrate (CC) is a nonsteroidal compound and induces ovulation indirectly. The wide usage of the CC raises a question; is it safe or not? In the light of this question, this review aimed to highlight all researches and insights into the association between the use of CC and risk of genotoxicity, cytotoxicity, embryotoxicity, teratogenicity and risk of different cancer types. We conducted a MEDLINE/PubMed, Scopus, Web of Science, Google Scholar search. After a careful screening process of all authors, 32 of these articles were considered as appropriate, and reviewed. Our evaluations showed that CC has genotoxic, cytotoxic, embryotoxic and teratogenic properties. There is no association between the use of CC and risk of ovarian, breast, uterine, cervix, endometrium, lung, colorectal cancer, and lymphoma. However, risk increased especially after 6 cycles of use and especially in nulligravid women. The use of CC should be restricted to 6 cycles. Moreover, malignant melanoma and thyroid cancer risk was found to be higher among CC treated women in almost all studies. Further works should be conducted especially in animal models to assess its risk features.

Oncofertility in sarcoma patients

Treatment for sarcoma can significantly decrease fertility, both due to the irradiation of gonads, and the impact of chemotherapy on gametogenesis. Infertility in cancer survivors causes significant regret and decreased quality of life in their adulthood. As this cancer mainly affects children and young adults, fertility preservation is an essential part of survivorship care, however it remains one of the least implemented services in adolescent and young adult cancer patients. Success of fertility preservation is highly dependent on the referral prior to oncologic treatment. Early patient counseling with possible consult with oncofertility specialists should be offered to every oncologic patient in reproductive age or younger. There are several options available and in continuous evolution for fertility preservation. Cryopreservation of sperm and oocytes constitutes nowadays the standard of care, and should be offered to all patients. Other methods currently under development will potentially bring in the future reliable options for fertility preservation in a wider range of patients, such as those in pre-pubertal age at the time of diagnosis, or with an insufficient sperm count for semen banking. These include testicular sperm extraction (TESE), autologous ovarian tissue transplant, and in vitro maturation of gametes. Novel therapies such as molecular-targeted agents offer a safer toxicity profile regarding fertility, but further research is required to evaluate their impact on the long term, both alone and in combination therapies. Difficulties to access fertility preservation and its costs remain a significant impediment for many patients in need. Warranting access to all sarcoma patients should be a priority in all healthcare professionals involved in their care.

[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.

Long-term effects of repeated superovulation on the uterus and mammary gland in rhesus monkeys

PURPOSE

The aim of this study is to evaluate the effect of repeated controlled ovarian hyperstimulation (COH) on the structure and function of the uterus and mammary gland.

METHODS

Three adult female rhesus monkeys were superovulated up to four times, and three spontaneously ovulating monkeys were used as controls. After a 5-year period, the uterus and mammary gland tissue samples were collected for examination of their structure and function. Further, the expression of certain tumor markers was examined to assess the cancer risk for each organ.

RESULTS

Expression of Wnt7a (associated with the functional/developmental status of the uterus) was significantly decreased in the uterus of superovulated monkeys, and decreased expression of proliferation marker PCNA was found in uterine cells. Meanwhile, abnormal Golgi-derived secretory vesicles with an irregular shape were observed in the mammary glands of the superovulated monkeys, and decreased PCNA expression together with increased expression of caspase-3 (an apoptosis marker) was indicated in the mammary cells. The expression of tumor molecular markers of the uterus and mammary gland was not significantly different between the two groups.

CONCLUSIONS

Repeated COH affects the expression of the uterine development-related gene several years later, and uterine cells exhibited a low proliferation status. The ultrastructure of the mammary gland epithelial cells was abnormal, and the cells exhibited both low proliferation and high apoptosis status. Cancer risk for these organs was not observed. Given that primates are the closest relatives of humans, the results obtained from this study provide more intuitive information for optimization of clinical COH.

Cancer Risk in Women Treated with Fertility Drugs According to Parity Status-A Registry-based Cohort Study

Background: Long-term safety of assisted reproductive techniques (ART) is of interest as their use is increasing. Cancer risk is known to be affected by parity. This study examined the risk of cancer after fertility treatment, stratified by women's parity.Methods: Data were obtained from all women (n = 1,353,724) born in Norway between 1960 and 1996. Drug exposure data (2004-2014) were obtained from the Norwegian Prescription Database (drugs used in ART and clomiphene citrate). The Medical Birth Registry of Norway provided parity status. HRs were calculated for all site cancer, breast, cervical, endometrial, ovarian, colorectal, central nervous system, thyroid cancer, and malignant melanoma.Results: In 12,354,392 person-years of follow-up, 20,128 women were diagnosed with cancer. All-site cancer risk was 1.14 [95% confidence interval (95% CI), 1.03-1.26] and 1.10 (95% CI, 0.98-1.23) after clomiphene citrate and ART exposure, respectively. For ovarian cancer, a stronger association was observed for both exposures in nulliparous (HR, 2.49; 95% CI, 1.30-4.78; and HR, 1.62; 95% CI, 0.78-3.35) versus parous women (HR, 1.37; 95% CI, 0.64-2.96; and HR, 0.87; 95% CI, 0.33-2.27). Elevated risk of endometrial cancers was observed for clomiphene citrate exposure in nulliparous women (HR, 4.49; 95% CI, 2.66-7.60 vs. HR, 1.52; 95% CI, 0.67-3.42). Risk was elevated for breast cancer in parous women exposed to clomiphene citrate (HR, 1.26; 95% CI, 1.03-1.54) for thyroid cancer and among nulliparous women after ART treatment (HR, 2.19; 95% CI, 1.08-4.44).Conclusions: Clomiphene citrate appears associated with increased risk of ovarian and endometrial cancer. Elevations in risks of breast and thyroid cancer were less consistent across type of drug exposure and parity.Impact: Continued monitoring of fertility treatments is warranted. Cancer Epidemiol Biomarkers Prev; 26(6); 953-62. ©2017 AACR.

Polycystic ovary syndrome and risk of endometrial, ovarian, and breast cancer: a systematic review

Background

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder with an estimated prevalence of 4–21% in reproductive aged women. The altered metabolic and hormonal environment among women with PCOS may increase their risk of some types of cancer.

Methods

We performed a comprehensive review of the literature using numerous search terms for all studies examining the associations between polycystic ovary syndrome and related characteristics and cancer published in English through October 2016. This review summarizes the epidemiological findings on the associations between PCOS and endometrial, ovarian, and breast cancers and discusses the methodological issues, complexities, and underlying mechanisms of these associations.

Results

We identified 11 individual studies and 3 meta-analyses on the associations between PCOS and endometrial cancer, 8 studies and 1 meta-analysis for ovarian cancer, and 10 studies and 1 meta-analysis for breast cancer. Multiple studies reported that women with PCOS were at a higher risk for endometrial cancer; however, many did not take into account body mass index (BMI), a strong and well-established risk factor for endometrial cancer. The association with ovarian cancer was less clear, but a potentially increased risk of the borderline serous subtype was reported by two studies. No consistent association between PCOS risk and breast cancer was observed.

Conclusion

The associations between PCOS and endometrial, ovarian, and breast cancer are complex, with the need to consider many methodological issues in future analyses. Larger well-designed studies, or pooled analyses, may help clarify these complex associations.

Fertility drugs and cancer: a guideline

Methodological limitations in studying the association between the use of fertility drugs and cancer include the inherent increased risk of cancer in women who never conceive, the low incidence of most of these cancers, and that the age of diagnosis of cancer typically is many years after fertility drug use. Based on available data, there does not appear to be a meaningful increased risk of invasive ovarian cancer, breast cancer, or endometrial cancer following the use of fertility drugs. Several studies have shown a small increased risk of borderline ovarian tumors; however, there is insufficient consistent evidence that a particular fertility drug increases the risk of borderline ovarian tumors, and any absolute risk is small. Given the available literature, patients should be counseled that infertile women may be at an increased risk of invasive ovarian, endometrial, and breast cancer; however, use of fertility drugs does not appear to increase this risk.

Cancer and fertility preservation: international recommendations from an expert meeting

In the last years, thanks to the improvement in the prognosis of cancer patients, a growing attention has been given to the fertility issues. International guidelines on fertility preservation in cancer patients recommend that physicians discuss, as early as possible, with all patients of reproductive age their risk of infertility from the disease and/or treatment and their interest in having children after cancer, and help with informed fertility preservation decisions. As recommended by the American Society of Clinical Oncology and the European Society for Medical Oncology, sperm cryopreservation and embryo/oocyte cryopreservation are standard strategies for fertility preservations in male and female patients, respectively; other strategies (e.g. pharmacological protection of the gonads and gonadal tissue cryopreservation) are considered experimental techniques. However, since then, new data have become available, and several issues in this field are still controversial and should be addressed by both patients and their treating physicians.In April 2015, physicians with expertise in the field of fertility preservation in cancer patients from several European countries were invited in Genova (Italy) to participate in a workshop on the topic of "cancer and fertility preservation". A total of ten controversial issues were discussed at the conference. Experts were asked to present an up-to-date review of the literature published on these topics and the presentation of own unpublished data was encouraged. On the basis of the data presented, as well as the expertise of the invited speakers, a total of ten recommendations were discussed and prepared with the aim to help physicians in counseling their young patients interested in fertility preservation.Although there is a great interest in this field, due to the lack of large prospective cohort studies and randomized trials on these topics, the level of evidence is not higher than 3 for most of the recommendations highlighting the need of further research efforts in many areas of this field. The participation to the ongoing registries and prospective studies is crucial to acquire more robust information in order to provide evidence-based recommendations.

HIV-serodiscordant couples desiring a child: 'treatment as prevention,' preexposure prophylaxis, or medically assisted procreation?

OBJECTIVE

We sought to assess the residual risk of HIV transmission, cost, and cost-effectiveness of various strategies that can help fertile HIV-uninfected female/HIV-1-infected male on combination antiretroviral therapy with plasma HIV RNA <50 copies/mL couples to have a child: (1) unprotected sexual intercourse (treatment as prevention); (2) treatment as prevention limited to fertile days (targeting fertile days); (3) treatment as prevention with preexposure prophylaxis (tenofovir/emtricitabine); (4) treatment as prevention and preexposure prophylaxis limited to fertile days; or (5) medically assisted procreation (MAP).

STUDY DESIGN

This was a model-based, cost-effectiveness analysis performed from a French societal perspective. Input parameters derived from international literature included: 85% probability of live births in different strategies, 0.0083%/mo HIV transmission risk with unprotected vaginal intercourse, 1% HIV mother-to-child transmission rate, and 4.4% birth defect risk related to combination antiretroviral therapy when the mother is infected at conception. Targeting fertile days and preexposure prophylaxis were estimated to decrease the risk of HIV transmission by 80% and 67%, respectively, and by 93.4% for preexposure prophylaxis limited to fertile days (the relative risk of transmission considering the combination of both strategies assuming to be (1-80%)*(1-67%) = 16.6% in basecase). Tenofovir/emtricitabine monthly cost was set at €540.

RESULTS

The HIV transmission risk was highest with treatment as prevention and lowest for MAP (5.4 and 0.0 HIV-infected women/10,000 pregnancies, respectively). Targeting fertile days was more effective than preexposure prophylaxis (0.9 vs 1.8) and associated with lowest costs. Preexposure prophylaxis limited to fertile days was more effective than targeting fertile days (0.3 vs 0.9) with a cost-effectiveness ratio of €1,130,000/life year saved; MAP cost-effectiveness ratio when compared with preexposure prophylaxis limited to fertile days was €3,600,000/life year saved. Results were robust to multiple sensitivity analyses.

CONCLUSION

Targeting fertile days is associated with a low risk of HIV transmission in fertile HIV-uninfected female/male with controlled HIV-1 infection couples. The risk is lower with preexposure prophylaxis limited to fertile days, or MAP, but these strategies are associated with unfavorable cost-effectiveness ratios under their current costs.

Effects of fertility drugs on cancers other than breast and gynecologic malignancies

OBJECTIVE

To examine the relationship of ovulation-stimulating drugs to risk of cancers other than breast and gynecologic malignancies.

DESIGN

Retrospective cohort study, with additional follow-up since initial report.

SETTING

Reproductive endocrinology practices.

PATIENT(S)

Among a cohort of 12,193 women evaluated for infertility between 1965 and 1988, a total of 9,892 women (81.1% of the eligible population) were followed through 2010, via passive and active (questionnaire) approaches.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Hazard ratios (HRs) and 95% confidence intervals (CIs) for various fertility treatment parameters for select cancers.

RESULT(S)

During 30.0 median years of follow-up (285,332 person-years), 91 colorectal cancers, 84 lung cancers, 55 thyroid cancers, and 70 melanomas were diagnosed among study subjects. Clomiphene citrate (CC), used by 38.1% of patients, was not associated with colorectal or lung cancer risks, but was related significantly to melanoma (HR = 1.95; 95% CI: 1.18-3.22), and non-significantly to thyroid cancer risks (HR = 1.57; 95% CI: 0.89-2.75). The highest melanoma risks were seen among those with the lowest drug exposure levels, but thyroid cancer risk was greatest among the heavily exposed patients (HR = 1.96; 95% CI: 0.92-4.17 for those receiving >2,250 mg). Clomiphene citrate-associated risks for thyroid cancer were somewhat higher among nulligravid, compared with gravid, women, but did not differ according to distinct causes of infertility. Gonadotropins, used by only 9.7% of subjects, were not related to risk of any of the assessed cancers.

CONCLUSION(S)

Our results provide support for continued monitoring of both melanoma and thyroid cancer risk among patients receiving fertility drugs.

Cancer risk among parous women following assisted reproductive technology

STUDY QUESTION

Do women who give birth after assisted reproductive technology (ART) have an increased risk of cancer compared with women who give birth without ART?

SUMMARY ANSWER

Without correction, the results indicate an increase in overall cancer risk, as well as a 50% increase in risk of CNS cancer for women giving birth after ART, however the results were not significant after correcting for multiple analyses.

WHAT IS KNOWN ALREADY

Studies regarding the effects of hormonal treatments involved with ART on subsequent cancer risk have provided inconsistent results, and it has also been suggested that infertility itself could be a contributory factor.

STUDY DESIGN, SIZE, DURATION

A population-based cohort consisting of all women registered in the Medical Birth Registry of Norway as having given birth between 1 January 1984 and 31 December 2010 was assembled (n = 812 986). Cancers were identified by linkage to the Cancer Registry of Norway. Study subjects were followed from start of first pregnancy during the observational period until the first cancer, death, emigration, or 31 December 2010.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Of the total study population (n = 806 248), 16 525 gave birth to a child following ART. Cox regression analysis computed hazard ratios (HR) and 95% confidence intervals (CI) comparing cancer risk between ART women and non-ART women; for overall cancer, and for cervical, ovarian, uterine, central nervous system (CNS), colorectal and thyroid cancers, and for malignant melanoma.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 22 282 cohort members were diagnosed with cancer, of which 338 were ART women and 21 944 non-ART women. The results showed an elevated risk in one out of seven sites for ART women. The HR for cancer of the CNS was 1.50 (95% CI 1.03- 2.18), and among those specifically subjected to IVF (without ICSI) the HR was 1.83 (95% CI 1.22-2.73). Analysis of risk of overall cancer gave an HR of 1.16 (95% CI 1.04-1.29). Among those who had delivered only one child by the end of follow-up, the HR for ovarian cancer was 2.00 (95% CI 1.08-3.65), and for those nulliparous at entry the HR was 1.80 (95% CI 1.04-3.11). However, all findings became non-significant after correcting for multiple analyses.

LIMITATIONS, REASONS FOR CAUTION

The results of elevated risk of overall cancer and CNS cancer lost significance when adjusting for multiple analyses, implying an important limitation of the study. The follow-up time was relatively short, especially for ART women. In addition, as the cohort was relatively young, there were few incident cancers, especially for some rarer cancer forms, such as uterine cancer. Risk assessments according to different causes of infertility could not be done.

WIDER IMPLICATIONS OF THE FINDINGS

In light of the findings in the present study, further studies should be made on risk of CNS and ovarian cancer, and continued monitoring of all those treated with ART is encouraged. Our findings may only be generalizable to women who give birth after ART, and the risk for women who remain nulliparous after ART remains to be assessed.

STUDY FUNDING/COMPETING INTEREST

The study was funded by the Norwegian National Advisory Unit on Women's Health. All authors claim no competing interests.

Reproduction and breast cancer risk

Reproduction is doubtlessly one of the main biological meanings of life. It is therefore not surprising that various aspects of reproduction impact on breast cancer risk. Various developmental levels may become targets of breast tumorigenesis. This review follows the chronologic sequence of events in the life of a female at risk, starting with the intrauterine development. Furthermore, the influence of both contraceptive measures and fertility treatment on breast cancer development is dealt with, as well as various pregnancy-associated factors, events, and perinatal outcomes. Finally, the contribution of breast feeding to a reduced breast cancer risk is discussed.

Breast cancer incidence after hormonal treatments for infertility: systematic review and meta-analysis of population-based studies

The increasing practice of hormonal infertility treatments (HITs) raised concerns about their effects on breast cancer (BC) risk. Available evidence reported conflicting results. The aim of this study was to assess the potential association between HITs and BC risk. The literature was searched through November 2014. Eligible studies included cohort studies reporting BC incidence in women undergone HITs. Data were analyzed with standard meta-analytic techniques. Subgroup analyses were performed by type of intervention (IVF vs. NO IVF), follow-up duration (<10 vs. >10 years), and type of control (population vs. infertile). 20 eligible studies (207.914 women, 2347 BC) were retrieved: no increased risk was detected (SRR = 1.05, 95 % CI 0.96-1.14), with a significant heterogeneity (I (2) = 59 %, p = 0.001) among studies. In the seven studies with the in vitro fertilization (IVF) procedure, no increase in BC risk was observed (SRR = 0.96, 95 % CI 0.80-1.14); in the three NO IVF studies, an increased BC risk was identified (SRR = 1.26, 95 %CI 1.06-1.50). A borderline interaction between type of intervention (IVF vs. NO IVF) and BC risk was observed (p = 0.06). An increased risk with longer follow-up (≥10 vs. <10 years) was detected (SRR = 1.13, 95 % CI 1.02-1.26 vs. SRR = 0.95, 95 % CI 0.85-1.06). Overall, HITs are not associated with an increased BC risk. In particular, no increased risk was observed in women undergoing IVF. Conversely, an increased in BC risk cannot be ruled out with older treatment protocols based on clomiphene. The long-term administration of clomiphene outside the current indications should be discouraged because of a possible increase in BC risk.

Risk of breast cancer following fertility treatment--a registry based cohort study of parous women in Norway

Despite increasing numbers of women availing themselves of assisted reproductive technology (ART), effects on cancer risk remain unresolved. Given hormonal exposures, breast cancer risk is of particular concern. The aim of this study is to investigate breast cancer risk amongst women giving birth following ART as compared to that amongst women who gave birth without ART. Data on all women who gave birth in Norway with or without ART, between 1984 and 2010 were obtained from the Medical Birth Registry of Norway (MBRN). 808,834 women eligible for study were linked to the Cancer Registry of Norway. Cox proportional models computed hazard ratios (HR) and 95% confidence intervals (CI) of breast cancer between the two groups, adjusting for age, parity, age at first birth, calendar period and region of residence. In total, 8,037 women were diagnosed with breast cancer during the study period, 138 ART women and 7,899 unexposed. Total follow-up time was 12,401,121 person-years (median 16.0); median age at entry was 32.5 years (range 18.6-49.9) for ART women and 26.3 (range 10.5-54.6) for unexposed. Women exposed to ART had an elevated risk of breast cancer (adjusted HR 1.20, 95% CI 1.01-1.42). Subgroup analyses gave an HR of 1.30 (95% CI 1.07-1.57) for women treated with IVF and 1.35 (95 % CI 1.07-1.71) for women with follow-up >10 years, compared with controls. Our findings of increased risk in the study population warrant continued monitoring of women treated with ART as this population advances into more typical cancer age ranges.