Infertility and risk of postmenopausal breast cancer in the women's health initiative

PURPOSE

Although infertility (i.e., failure to conceive after ≥ 12 months of trying) is strongly correlated with established breast cancer risk factors (e.g., nulliparity, number of pregnancies, and age at first pregnancy), its association with breast cancer incidence is not fully understood. Previous studies were primarily small clinic-based or registry studies with short follow-up and predominantly focused on premenopausal breast cancer. The objective of this study was to assess the relationship between infertility and postmenopausal breast cancer risk among participants in the Women's Health Initiative (analytic sample = 131,784; > 25 years of follow-up).

METHODS

At study entry, participants were asked about their pregnancy history, infertility history, and diagnosed reasons for infertility. Incident breast cancers were self-reported with adjudication by trained physicians reviewing medical records. Cox proportional hazards models were used to estimate risk of incident postmenopausal breast cancer for women with infertility (overall and specific infertility diagnoses) compared to parous women with no history of infertility. We examined mediation of these associations by parity, age at first term pregnancy, postmenopausal hormone therapy use at baseline, age at menopause, breastfeeding, and oophorectomy.

RESULTS

We observed a modest association between infertility (n = 23,406) and risk of postmenopausal breast cancer (HR = 1.07; 95% CI 1.02-1.13). The association was largely mediated by age at first term pregnancy (natural indirect effect: 46.4% mediated, CI 12.2-84.3%).

CONCLUSION

These findings suggest that infertility may be modestly associated with future risk of postmenopausal breast cancer due to age at first pregnancy and highlight the importance of incorporating reproductive history across the life course into breast cancer analyses.

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.

Risk of ovarian cancer in women who give birth after assisted reproductive technology (ART)-a registry-based Nordic cohort study with follow-up from first pregnancy

BACKGROUND

There is concern that assisted reproductive technology (ART) may increase ovarian cancer risk, but previous studies are inconclusive. We compared ovarian cancer risk for women who gave birth after ART vs natural conception.

METHODS

Through linkage of nationwide registry data, we followed 3,303,880 initially nulliparous women in Denmark (1994-2014), Finland (1990-2014), Norway (1984-2015) and Sweden (1985-2015) from first pregnancy ≥22 weeks to ovarian cancer, emigration, death or end of follow-up (2014/2015). We estimated hazard ratios (HRs), adjusting for age, parity, maternal birth year and country, and for body mass index and smoking in subsamples.

RESULTS

Mean age at first birth was 27.7 years. During a mean follow-up of 14.4 person-years, 2683 participants (0.08%) developed ovarian cancer; 135 after ART and 2548 after natural conception only (incidence rates 11.6 and 5.5 per 100,000 person-years, respectively). The risk was higher for women who ever gave birth after ART (HR 1.70, 95% confidence interval 1.42-2.03) compared to natural conception. Associations were stronger for conventional in vitro fertilisation than for intracytoplasmic sperm injection.

CONCLUSIONS

Among parous women, ART-conception was associated with a higher risk of ovarian cancer than natural conception. Further studies should decipher whether this is causal or confounded by infertility or other factors.

Risk of colorectal cancer after use of fertility drugs-results from a large Danish population-based cohort of women with infertility

OBJECTIVE

To study the association between use of fertility drugs and colorectal cancer among women with infertility.

DESIGN

Population-based cohort study.

SETTING

Not applicable.

PATIENT(S)

The study cohort was obtained from the Danish Infertility Cohort and consisted of all women with infertility aged 20-45 years living in Denmark during 1995-2017.

INTERVENTION(S)

Information on the use of specific types of fertility drugs, colorectal cancer diagnoses, covariates, and vital status were obtained from the Danish Infertility Cohort and Danish national registers.

MAIN OUTCOME MEASURE(S)

Cox proportional hazard models adjusted for potential confounders were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for colorectal cancer overall and rectal and colon cancer separately.

RESULTS(S)

Among 148,036 women in the final study cohort, 205 women were diagnosed with colorectal cancer. Ever use of clomiphene citrate (CC) was associated with a lower rate of colorectal cancer (unadjusted HR, 0.67; 95% CI, 0.51-0.89; adjusted HR, 0.68; 95% CI, 0.50-0.93). However, the lower rate was only seen among women who first used CC >8 years ago (unadjusted HR, 0.56; 95% CI, 0.41-0.76; adjusted HR, 0.52; 95% CI, 0.36-0.75). No marked associations were found between the use of any of other types of fertility drugs and colorectal cancer. The results for colon and rectal cancer analyzed separately were similar, except for a suggestion of a decreased risk of rectal cancer associated with the use of gonadotropins (adjusted HR, 0.46; 95% CI, 0.20-1.08).

CONCLUSION(S)

Among women with infertility, the use of most types of fertility drugs was not associated with colorectal cancer. However, CC may decrease the risk of colorectal cancer and gonadotropins might decrease the risk of rectal cancer, but we cannot rule out that these findings may be more related to the underlying conditions in these women or are chance findings. Consequently, the results from this study should be investigated further in large epidemiological studies.

Tumors of the central nervous system among women treated with fertility drugs: a population-based cohort study

PURPOSE

To investigate the association between fertility drugs and tumors of the central nervous system (CNS).

METHODS

This cohort study was based on The Danish Infertility Cohort and included 148,016 infertile women living in Denmark (1995-2017). The study cohort was linked to national registers to obtain information on use of specific fertility drugs, cancer diagnoses, covariates, emigration, and vital status. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for all CNS tumors and separately for gliomas, meningiomas and diverse benign tumors of the brain and other parts of the CNS.

RESULTS

During a median 11.3 years of follow-up, 328 women were diagnosed with CNS tumors. No marked associations were observed between use of the fertility drugs clomiphene citrate, gonadotropins, gonadotropin-releasing hormone receptor modulators and progesterone and CNS tumors. However, use of human chorionic gonadotropin was associated with a decreased rate of meningiomas (HR 0.49 95% CI 0.28-0.87). No clear associations with CNS tumors were observed according to time since first use or cumulative dose for any of the fertility drugs.

CONCLUSION

No associations between use of most types of fertility drugs and CNS tumors were observed. However, our findings only apply to premenopausal women and additional studies with longer follow-up time are necessary.

Hospitalizations up to 8 years following delivery in assisted reproductive technology-treated and subfertile women

OBJECTIVE

To investigate hospitalizations up to 8 years after live birth among women who used assisted reproductive technology (ART) or who were subfertile compared with women who conceived naturally.

DESIGN

Retrospective cohort.

SETTING

Deliveries among privately insured women aged ≥18 years between 2004 and 2017 from Massachusetts state vital records were linked to the Society for Assisted Reproductive Technology Clinic Outcome Reporting System and hospital observational/inpatient stays.

PATIENT(S)

We compared patients with ART, medically assisted reproduction (MAR), and unassisted subfertile (USF) delivery with those with fertile delivery.

INTERVENTION(S)

NA.

MAIN OUTCOME MEASURE(S)

Postdelivery hospitalization information was derived from the International Classification of Diseases codes for discharges and combined by type. The relative risks and 95% confidence intervals (CIs) of hospitalization for up to the first 8 years postdelivery were modeled.

RESULT(S)

Among 492,515 deliveries, 5.6% used ART, 1.6% used MAR, and 1.8% were USF. Compared with fertile deliveries, deliveries that used ART or MAR or were USF were more likely to have hospital utilization (inpatient or observational stay) for any reason for up to 8 years of follow-up (USF, adjusted relative risk [aRR], 1.18 [95% CI, 1.12-1.25]; MAR, aRR, 1.20 [1.13-1.27]; and ART, aRR, 1.29 [1.25-1.34]). Assisted reproductive technology deliveries had an increased risk of hospitalization for conditions of the cardiovascular system (aRR, 1.31 [95% CI, 1.20-1.41]), overweight/obesity (aRR, 1.30 [1.17-1.44]), diabetes (aRR, 1.25 [1.05-1.49]), reproductive tract (aRR, 1.62 [1.47-1.79]), digestive tract (aRR, 1.39 [1.30-1.49]), thyroid (aRR, 2.02 [1.80-2.26]), respiratory system (aRR, 1.13 [1.03-1.24]), and cancer (aRR, 1.40 [1.18-1.65]) up to 8 years after delivery. Deliveries with MAR and subfertility had similar patterns of hospitalization as ART deliveries.

CONCLUSION(S)

Women who conceived through fertility treatment or experienced subfertility were at increased risk of subsequent hospitalization resulting from a variety of chronic and acute conditions.

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.

Ovarian stimulation for fertility treatments and risk of breast cancer: a matched cohort study

STUDY QUESTION

Is there a difference in the breast cancer risk among women who underwent ART treatments compared to those who underwent medically assisted reproduction (MAR) infertility treatments or women of reproductive age in the general population?

SUMMARY ANSWER

The risk of breast cancer among women treated by ART was similar to the risk among women treated by MAR and women who did not undergo fertility treatments.

WHAT IS KNOWN ALREADY

Studies investigating breast cancer risk in women who have undergone fertility treatments have provided conflicting results.

STUDY DESIGN, SIZE, DURATION

A retrospective, population-based cohort study included women who underwent ART or MAR treatments and women who did not undergo fertility treatments from 1994 to 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women who underwent ART were matched one to one with women who underwent MAR treatments and one to one with woman from the general population of reproductive age, by year of birth and year of first delivery or nulliparity status. MAR women were also matched to ART women by treatment initiation calendar year. All included women were members of Maccabi Healthcare Services. Data regarding demographics, fertility treatments, BRCA mutation and possible confounders were obtained from the computerized database of electronic health records. The incidence of breast cancer after fertility treatments was compared to the matched controls.

MAIN RESULTS AND THE ROLE OF CHANCE

Of 8 25 721 women of reproductive age, 32 366 women who underwent ART were matched with patients treated by MAR (n = 32 366) and 32 366 women of reproductive age. A total of 984 women (1.0%) were diagnosed with breast cancer (mean follow-up period, 9.1 ± 6.3 years; interquartile range [IQR], 3.8-13.7 years). The incidence rates of breast cancer per 10 000 person-years were 11.9 (95% CI, 10.7-13.3), 10.7 (95% CI, 9.6-11.9) and 10.7 (95% CI, 9.6-12.0) in the ART group, MAR group and general population, respectively. The crude risk for breast cancer was similar in the ART group compared with the general population (hazard ratio (HR) = 1.10, 95% CI, 0.94-1.28) and in the ART group compared with the MAR group (HR = 1.00, 95% CI, 0.86-1.16). Further adjustment for age, BMI, smoking, socioeconomic status and parity did not substantially impact the hazard rates for breast cancer (ART vs general population: HR = 1.10, 95% CI, 0.94-1.28; ART vs MAR: HR = 0.99, 95% CI, 0.85-1.16). Among women diagnosed with breast cancer, the prevalence of BRCA1/2 mutations and tumour staging did not differ between the ART, MAR and general population groups. Among women who underwent ART, no correlation was found between breast cancer and the number of ART cycles or the use of recombinant medications or urine-derived medications.

LIMITATIONS, REASONS FOR CAUTION

The mean age of women at the end of follow-up was only 42 years thus the study was not powered to detect potential differences in the risk of postmenopausal breast cancer. In addition, we did not sub-classify the exposed patients by the reason for infertility.

WIDER IMPLICATIONS OF THE FINDINGS

Breast cancer incidence following ART was comparable to that in the general population or following MAR. Women undergoing fertility treatments and their clinicians may be reassured about the safety of assisted reproduction technologies in terms of premenopausal breast cancer risk.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was used and there are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Assisted reproductive technology treatment and risk of breast cancer: a population-based cohort study

STUDY QUESTION

Is there an increased risk of breast cancer among women after ART treatment including ovarian hormone stimulation?

SUMMARY ANSWER

The risk of breast cancer was slightly increased among women after ART treatment compared to age-matched, untreated women in the background population, and the risk was further increased among women initiating ART treatment when aged 40+ years.

WHAT IS KNOWN ALREADY

The majority of breast cancer cases are sensitive to oestrogen, and ovarian hormone stimulation has been suggested to increase the risk of breast cancer by influencing endogenous oestrogen levels. Previous studies on ART treatment and breast cancer have varied in their findings, but several studies have small sample sizes or lack follow-up time and/or confounder adjustment. Recent childbirth, nulliparity and higher socio-economic status are breast cancer risk factors and the latter two are also associated with initiating ART treatment.

STUDY DESIGN, SIZE, DURATION

The Danish National ART-Couple II (DANAC II) cohort includes women treated with ART at public and private fertility clinics in 1994-2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women with no cancer prior to ART treatment were included (n = 61 579). Women from the background population with similar age and no prior history of ART treatment were randomly selected as comparisons (n = 579 760). The baseline mean age was 33.1 years (range 18-46 years). Results are presented as hazard ratios (HRs) with corresponding CIs.

MAIN RESULTS AND THE ROLE OF CHANCE

During follow-up (median 9.69 years among ART-treated and 9.28 years among untreated), 5861 women were diagnosed with breast cancer, 695 among ART-treated and 5166 among untreated women (1.1% versus 0.9%, P < 0.0001). Using Cox regression analyses adjusted for nulliparity, educational level, partnership status, year, maternal breast cancer and age, the risk of breast cancer was slightly increased among women treated with ART (HR 1.14, 95% CI 1.12-1.16). All causes of infertility were slightly associated with breast cancer risk after ART treatment. The risk of breast cancer increased with higher age at ART treatment initiation and was highest among women initiating treatment at age 40+ years (HR 1.37, 95% CI 1.29-1.45). When comparing women with a first birth at age 40+ years with or without ART treatment, the increased risk among women treated with ART persisted (HR 1.51, 95% CI 1.09-2.08).

LIMITATIONS, REASONS FOR CAUTION

Although this study is based on a large, national cohort of women, more research with sufficient power and confounder adjustment is needed, particularly in cohorts with a broad age representation.

WIDER IMPLICATIONS OF THE FINDINGS

An increased risk of breast cancer associated with a higher age at ART treatment initiation has been shown. Ovarian stimulation may increase the risk of breast cancer among women initiating ART treatment when aged 40+ years. Age-related vulnerability to hormone exposure or higher hormone doses during ART treatment may explain the increased risk.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by a PhD grant to D.V. from the Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. Funding for establishing the DANAC II cohort was received from the Ebba Rosa Hansen Foundation. The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

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.

Use of Fertility Drugs and Risk of Malignant Melanoma: Results from a Large Danish Population-Based Cohort Study

Fertility drugs have not definitively been linked to malignant melanoma. By the use of data from a large nationwide cohort of women aged 20.0-45.0 years and living in Denmark between January 1, 1995 and December 31, 2011, we assessed the association between the use of fertility drugs and the risk of malignant melanoma. Information on fertility status and the use of fertility drugs was obtained from the population-based Danish Infertility Cohort. Cox proportional hazard regression models were applied to estimate hazard ratios and 95% confidence intervals with adjustment for potential confounders. The study population comprised 1,330,954 women, of whom 86,231 (6.5%) were treated with fertility drugs. During a median follow-up of 21.0 years, 6,139 women were diagnosed with malignant melanoma. Compared with fertile women, women with fertility challenges who had used any fertility drugs had an increased risk of malignant melanoma (hazard ratio = 1.14; 95% confidence interval = 1.02-1.27). Furthermore, the use of specific types of fertility drugs (clomiphene, gonadotropins, human chorionic gonadotropin, gonadotropin-releasing hormone preparations, and progesterone) was also associated with an increased risk of malignant melanoma, with hazard ratios ranging between 1.09 and 1.13; however, the association did not reach statistical significance. Our findings indicate that the use of fertility drugs was associated with a modestly increased risk of malignant melanoma.

Assisted reproductive technology and risk of ovarian cancer and borderline tumors in parous women: a population-based cohort study

The study aimed to investigate if assisted reproductive technology (ART) treatment or a diagnosis of infertility were associated with the risk of ovarian cancer or borderline ovarian tumors (BOT) in parous women. In a population-based register study of 1,340,097 women with a first live birth in Sweden 1982–2012, the relationship between ART treatments, infertility and incidence of ovarian cancer or BOT were investigated using Cox regression analysis. In the cohort, 38,025 women gave birth following ART, 49,208 following an infertility diagnosis but no ART and 1,252,864 without infertility diagnosis or ART. During follow-up, 991 women were diagnosed with ovarian cancer and 747 with BOT. Women who gave birth following ART had higher incidence of both ovarian cancer (adjusted hazard ratio [aHR] 2.43, 95% confidence interval [CI] 1.73–3.42) and BOT (aHR 1.91, 95% CI 1.27–2.86), compared to women without infertility. Compared to women with infertility diagnoses and non-ART births, women with ART births also had a higher incidence of ovarian cancer (aHR 1.79, 95% CI 1.18–2.71) and BOT (aHR 1.48, 95% CI 0.90–2.44). Our results suggest that women who have gone through ART have a higher risk of ovarian cancer and BOT. At least part of that risk seems to be due to the underlying infertility and not the treatment per se, since the increased risk was smaller when comparing to other infertile women. As ART treatments are becoming more common and ovarian cancer usually occur in women of advanced age, larger studies with longer follow-up are needed in order to confirm or refute our findings.

Risk of ovarian cancer in women treated with ovarian stimulating drugs for infertility

BACKGROUND

This is an updated version of the original Cochrane Review published in the Cochrane Library in 2013 (Issue 8) on the risk of ovarian cancer in women using infertility drugs when compared to the general population or to infertile women not treated. The link between fertility drugs and ovarian cancer remains controversial.

OBJECTIVES

To evaluate the risk of invasive ovarian cancer and borderline ovarian tumours in women treated with ovarian stimulating drugs for subfertility.

SEARCH METHODS

The original review included published and unpublished observational studies from 1990 to February 2013. For this update, we extended the searches from February 2013 to November 2018; we evaluated the quality of the included studies and judged the certainty of evidence by using the GRADE approach. We have reported the results in a Summary of findings table to present effect sizes across all outcome types.

SELECTION CRITERIA

In the original review and in this update, we searched for randomised controlled trials (RCTs) and non-randomised studies and case series including more than 30 participants.

DATA COLLECTION AND ANALYSIS

At least two review authors independently conducted eligibility and 'Risk of bias' assessments and extracted data. We grouped studies based on the fertility drug used for two outcomes: borderline ovarian tumours and invasive ovarian cancer. We conducted no meta-analyses due to expected methodological and clinical heterogeneity.

MAIN RESULTS

We included 13 case-control and 24 cohort studies (an additional nine new cohort and two case-control studies), which included a total of 4,684,724 women.Two cohort studies reported an increased incidence of invasive ovarian cancer in exposed subfertile women compared with unexposed women. One reported a standardised incidence ratio (SIR) of 1.19 (95% confidence interval (CI) 0.54 to 2.25) based on 17 cancer cases. The other cohort study reported a hazard ratio (HR) of 1.93 (95% CI 1.18 to 3.18), and this risk was increased in women remaining nulligravid after using clomiphene citrate (HR 2.49, 95% CI 1.30 to 4.78) versus multiparous women (HR 1.52, 95% CI 0.67 to 3.42) (very low-certainty evidence). The slight increase in ovarian cancer risk among women having between one and three cycles of in vitro fertilisation (IVF) was reported, but this was not clinically significant (P = 0.18). There was no increase in risk of invasive ovarian cancer after use of infertility drugs in women with the BRCA mutation according to one cohort and one case-control study. The certainty of evidence as assessed using GRADE was very low.For borderline ovarian tumours, one cohort study reported increased risk in exposed women with an SIR of 3.61 (95% CI 1.45 to 7.44), and this risk was greater after treatment with clomiphene citrate (SIR 7.47, 95% CI 1.54 to 21.83) based on 12 cases. In another cohort study, the risk of a borderline ovarian tumour was increased, with an HR of 4.23 (95% CI 1.25 to 14.33), for subfertile women treated with IVF compared with a non-IVF-treated group with more than one year of follow-up. A large cohort reported increased risk of borderline ovarian tumours, with HR of 2.46 (95% CI 1.20 to 5.04), and this was based on 17 cases. A significant increase in serous borderline ovarian tumours was reported in one cohort study after the use of progesterone for more than four cycles (risk ratio (RR) 2.63, 95% CI 1.04 to 6.64). A case-control study reported increased risk after clomiphene citrate was taken, with an SIR of 2.5 (95% CI 1.3 to 4.5) based on 11 cases, and another reported an increase especially after human menopausal gonadotrophin was taken (odds ratio (OR) 9.38, 95% CI 1.66 to 52.08). Another study estimated an increased risk of borderline ovarian tumour, but this estimation was based on four cases with no control reporting use of fertility drugs. The certainty of evidence as assessed using GRADE was very low.However, although some studies suggested a slight increase in risks of ovarian cancer and borderline ovarian tumour, none provided moderate- or high-certainty evidence, as summarised in the GRADE tables.

AUTHORS' CONCLUSIONS

Since the last version of this review, only a few new relevant studies have provided additional findings with supporting evidence to suggest that infertility drugs may increase the risk of ovarian cancer slightly in subfertile women treated with infertility drugs when compared to the general population or to subfertile women not treated. The risk is slightly higher in nulliparous than in multiparous women treated with infertility drugs, and for borderline ovarian tumours. However, few studies have been conducted, the number of cancers is very small, and information on the dose or type of fertility drugs used is insufficient.

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.

Risks of ovarian, breast, and corpus uteri cancer in women treated with assisted reproductive technology in Great Britain, 1991-2010: data linkage study including 2.2 million person years of observation

OBJECTIVE

To investigate the risks of ovarian, breast, and corpus uteri cancer in women who have had assisted reproduction.

DESIGN

Large, population based, data linkage cohort study.

SETTING AND PARTICIPANTS

All women who had assisted reproduction in Great Britain, 1991-2010, as recorded by the Human Fertilisation and Embryology Authority (HFEA).

INTERVENTIONS

HFEA fertility records for cohort members were linked to national cancer registrations.

MAIN OUTCOME MEASURES

Observed first diagnosis of ovarian, breast, and corpus uteri cancer in cohort members were compared with age, sex, and period specific expectation. Standardised incidence ratios (SIRs) were calculated by use of age, sex, and period specific national incidence rates.

RESULTS

255 786 women contributed 2 257 789 person years' follow-up. No significant increased risk of corpus uteri cancer (164 cancers observed v 146.9 cancers expected; SIR 1.12, 95% confidence interval 0.95 to 1.30) was found during an average of 8.8 years' follow-up. This study found no significantly increased risks of breast cancer overall (2578 v 2641.2; SIR 0.98, 0.94 to 1.01) or invasive breast cancer (2272 v 2371.4; SIR 0.96, 0.92 to 1.00). An increased risk of in situ breast cancer (291 v 253.5; SIR 1.15, 1.02 to 1.29; absolute excess risk (AER) 1.7 cases per 100 000 person years, 95% confidence interval 0.2 to 3.2) was detected, associated with an increasing number of treatment cycles (P=0.03). There was an increased risk of ovarian cancer (405 v 291.82; SIR 1.39, 1.26 to 1.53; AER 5.0 cases per 100 000 person years, 3.3 to 6.9), both invasive (264 v 188.1; SIR 1.40, 1.24 to 1.58; AER 3.4 cases per 100 000 person years, 2.0 to 4.9) and borderline (141 v 103.7; SIR 1.36, 1.15 to 1.60; AER 1.7 cases per 100 000 person years, 0.7 to 2.8). Increased risks of ovarian tumours were limited to women with endometriosis, low parity, or both. This study found no increased risk of any ovarian tumour in women treated because of only male factor or unexplained infertility.

CONCLUSIONS

No increased risk of corpus uteri or invasive breast cancer was detected in women who had had assisted reproduction, but increased risks of in situ breast cancer and invasive and borderline ovarian tumours were found in this study. Our results suggest that ovarian tumour risks could be due to patient characteristics, rather than assisted reproduction itself, although both surveillance bias and the effect of treatment are also possibilities. Ongoing monitoring of this population is essential.

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.

Ovarian stimulation and risk of breast cancer in Swedish women

OBJECTIVE

To investigate whether ovarian stimulation for treating infertility is associated with the risk of breast cancer.

DESIGN

Nationwide register-based cohort study.

SETTING

Not applicable.

PATIENT(S)

In a cohort of 1,340,211 women who gave birth 1982-2012, we investigated the relationship between assisted reproductive technology (ART) and incidence of breast cancer. Associations between any ovarian stimulation since 2005 and breast cancer incidence were studied in a separate cohort of 1,877,140 women born 1960-92. Both cohorts were followed through 2012.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer.

RESULT(S)

There was no increased risk of breast cancer in women who gave birth after ART compared with women who gave birth after spontaneous conception (adjusted HR, 0.84; 95% CI, 0.74-0.95). The incidence of breast cancer was not increased among women who received controlled ovarian stimulation or among women who received other hormonal fertility treatments since 2005, regardless of live birth (adjusted HR, 0.86; 95% CI, 0.69-1.07; and adjusted HR, 0.79; 95% CI, 0.60-1.05, respectively).

CONCLUSION(S)

No increased incidence of breast cancer was found among women who had gone through ovarian stimulations, including ART. These results are consistent with other studies and reassuring given the widespread and increasing use of ART.

Do women offered assisted reproduction technologies have a higher incidence of gynecologic cancer? A systematic review and meta-analysis

The last two decades have seen an increase in the number of women diagnosed with infertility. The consequent growth in the use of assisted reproductive technologies (ART) calls for the determination of its long-term effects, including the risk of cancer. Many studies have attempted to answer this question, albeit with contradictory results. This review aimed to assess whether assisted reproductive technologies are associated with an increased risk of gynecological cancer. A search for papers in the literature was carried out on MEDLINE, TRIP DATABASE and NICE, resulting in 11 studies enrolling 3,900,231 patients altogether. Of these, 118,320 were offered ART. The incidence of gynecological cancer in the group offered ART was 0.6%, while the incidence in the group not offered ART was 2.1%. Taking all the studies into consideration, women offered ART were not at greater risk of having gynecological cancer; instead, a protective association was found.

[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.

Risk of endometrial cancer in women treated with ovary-stimulating drugs for subfertility

BACKGROUND

Medical treatment for subfertility principally involves the use of ovary-stimulating agents, including selective oestrogen receptor modulators (SERMs), such as clomiphene citrate, gonadotropins, gonadotropin-releasing hormone (GnRH) agonists and antagonists, as well as human chorionic gonadotropin. Ovary-stimulating drugs may act directly or indirectly upon the endometrium (lining of the womb). Nulliparity and some causes of subfertility are recognized as risk factors for endometrial cancer.

OBJECTIVES

To evaluate the association between the use of ovary-stimulating drugs for the treatment of subfertility and the risk of endometrial cancer.

SEARCH METHODS

A search was performed in CENTRAL, MEDLINE (Ovid) and Embase (Ovid) databases up to July 2016, using a predefined search algorithm. A search in OpenGrey, ProQuest, ClinicalTrials.gov, ZETOC and reports of major conferences was also performed. We did not impose language and publication status restrictions.

SELECTION CRITERIA

Cohort and case-control studies reporting on the association between endometrial cancer and exposure to ovary-stimulating drugs for subfertility in adult women were deemed eligible.

DATA COLLECTION AND ANALYSIS

Study characteristics and findings were extracted by review authors independently working in pairs. Inconsistency between studies was quantified by estimating I2. Random-effects (RE) models were used to calculate pooled effect estimates. Separate analyses were performed, comparing treated subfertile women versus general population and/or unexposed subfertile women, to address the superimposition of subfertility as an independent risk factor for endometrial cancer.

MAIN RESULTS

Nineteen studies were eligible for inclusion (1,937,880 participants). Overall, the quality of evidence was very low, due to serious risk of bias and indirectness (non-randomised studies (NRS), which was reflected on the GRADE assessment.Six eligible studies, including subfertile women, without a general population control group, found that exposure to any ovary-stimulating drug was not associated with an increased risk of endometrial cancer (RR 0.96, 95% CI 0.67 to 1.37; 156,774 participants; very low quality evidence). Fifteen eligible studies, using a general population as the control group, found an increased risk after exposure to any ovary-stimulating drug (RR 1.75, 95% CI 1.18 to 2.61; 1,762,829 participants; very low quality evidence).Five eligible studies, confined to subfertile women (92,849 participants), reported on exposure to clomiphene citrate; the pooled studies indicated a positive association ( RR 1.32; 95% CI 1.01 to 1.71; 88,618 participants; very low quality evidence), although only at high dosage (RR 1.69, 95% CI 1.07 to 2.68; two studies; 12,073 participants) and at a high number of cycles (RR 1.69, 95% CI 1.16 to 2.47; three studies; 13,757 participants). Four studies found an increased risk of endometrial cancer in subfertile women who required clomiphene citrate compared to a general population control group (RR 1.87, 95% CI 1.00 to 3.48; four studies, 19,614 participants; very low quality evidence). These data do not tell us whether the association is due to the underlying conditions requiring clomiphene or the treatment itself.Using unexposed subfertile women as controls, exposure to gonadotropins was associated with an increased risk of endometrial cancer (RR 1.55, 95% CI 1.03 to 2.34; four studies; 17,769 participants; very low quality evidence). The respective analysis of two studies (1595 participants) versus the general population found no difference in risk (RR 2.12, 95% CI 0.79 to 5.64: very low quality evidence).Exposure to a combination of clomiphene citrate and gonadotropins, compared to unexposed subfertile women, produced no difference in risk of endometrial cancer (RR 1.18, 95% CI 0.57 to 2.44; two studies; 6345 participants; very low quality evidence). However, when compared to the general population, an increased risk was found , suggesting that the key factor might be subfertility, rather than treatment (RR 2.99, 95% CI 1.53 to 5.86; three studies; 7789 participants; very low quality evidence).

AUTHORS' CONCLUSIONS

The synthesis of the currently available evidence does not allow us to draw robust conclusions, due to the very low quality of evidence. It seems that exposure to clomiphene citrate as an ovary-stimulating drug in subfertile women is associated with increased risk of endometrial cancer, especially at doses greater than 2000 mg and high (more than 7) number of cycles. This may largely be due to underlying risk factors in women who need treatment with clomiphene citrate, such as polycystic ovary syndrome, rather than exposure to the drug itself. The evidence regarding exposure to gonadotropins was inconclusive.

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.

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.

Risk of Colorectal Cancer After Ovarian Stimulation for In Vitro Fertilization

BACKGROUND & AIMS

Apart from lifestyle factors, sex hormones also seem to have a role in the etiology of colorectal cancer. This raises interest in the possible effects of fertility drugs, especially because the use of ovarian stimulation for in vitro fertilization (IVF) has strongly increased over the past decades.

METHODS

In 1996, a nationwide cohort study was set up to examine cancer risk in a population that included 19,158 women who received ovarian stimulation for IVF (IVF group) and 5950 women who underwent subfertility treatments other than IVF (non-IVF group). Cancer incidence was ascertained through linkage with the Netherlands Cancer Registry. Colorectal cancer risk in the IVF group was compared with those in the general population and in the non-IVF group.

RESULTS

After a median follow-up of 21 years, 109 colorectal cancers were observed. Compared with the general population, risk of colorectal cancer was not increased in the IVF group (standardized incidence ratio, 1.00; 95% confidence interval [CI], 0.80-1.23), and was significantly decreased in the non-IVF group (standardized incidence ratio, 0.58; 95% CI, 0.36-0.88). Women in the IVF group had a significant increase in risk compared with women in the non-IVF group (multivariable-adjusted hazard ratio, 1.80; 95% CI, 1.10-2.94). No trend emerged with more IVF cycles or more ampules of gonadotropins administered. Colorectal cancer risk did not increase with longer follow-up periods.

CONCLUSIONS

Although women who receive ovarian stimulation for IVF do not have an increased risk for colorectal cancer compared with the general population, findings from our nationwide cohort study indicate that their risk is increased compared with women who received subfertility treatments other than IVF. Further research is warranted to examine whether ovarian stimulation for IVF contributes to development of colorectal cancer.

Investigation of Personality Traits between Infertile Women Submitted to Assisted Reproductive Technology or Surrogacy

Background

Personality traits affect human relationships, social interactions, treatment procedures, and essentially all human activities. The purpose of this study is to investigate the personality traitsincluding sensation seeking, flexibility, and happiness among a variety of infertile women who were apt to choose assisted reproductive technology (ART) or surrogacy.

Materials and Methods

This is a cross-sectional study that was performed on 251 infertile women who visited Isfahan and Tehran Reproductive Medicine Center. These fertility clinics are located in Isfahan and Tehran, Iran. In this study, 201 infertile women who underwent treatment using ART and 50 infertile women who tended to have surrogacy were chosen by convenience sampling. Zuckerman’s Sensation Seeking Scale Form V (SSS-V), Psychological Flexibility Questionnaire (adapted from NEO Personality Inventory-Revised) and Oxford Happiness Questionnaire (OHQ) were used as research instruments. All participants had to complete the research instruments in order to be included in this study. Data were analyzed by descriptive-analytical statistics and statistical tests including multivariate analysis of variance (MANOVA) and Z Fisher. Statistically significant effects were accepted for P<0.05.

Results

In the sensation-seeking variable, there was a meaningful difference between under-study groups. However, the flexibility and happiness variables did not have a significant difference between under-study groups (P<0.001). Interaction between education, employment, and financial status was effective in happiness of infertile women underwent ART (P<0.05), while age, education and financial status were also effective in happiness of infertile women sought surrogacy (P<0.05). A positive meaningful relationship was seen between sensation seeking and flexibility variables in both groups (P<0.05). And a negative meaningful relationship was seen between sensation seeking and happiness in infertile women who sought surrogacy (P<0.05). The difference in rate of relationship between sensation seeking and flexibility was meaningful in infertile women who sought either ART or surrogacy (P<0.05).

Conclusion

Sensations seeking as a personality trait is lower in infertile women who underwent treatment using ART compared women who tended to have surrogacy. This study shows that demographic variables are effective in happiness of infertile women. Also, there is a significant relation among sensation seeking, flexibility and happiness in infertile women.

[Impact of gonadotropins in women suffering from cancer]

The role of gonadotropins in the genesis of malignant diseases, in particular gynecologic cancers, is still controversial. The production of ovarian steroids, as a consequence of FSH and LH actions, may constitute a bias to draw reliable conclusions. Over the past decades, the use of exogenous gonadotropins has markedly increased in cancer patients, candidates for fertility preservation, and in survivors facing infertility as a consequence of gonadotoxic treatments. In gynecologic cancers, high serum estradiol levels may be problematic and can therefore be overcome by specific protocols of ovarian stimulation. However, exogenous gonadotropin administration in cancer patients should systematically be included in a multidisciplinary approach. The present article discusses the possible role of gonadotropins as tumorigenic factors and the use of exogenous gonadotropins in females suffering from cancer.

Assisted reproductive techniques after fertility-sparing treatments in gynaecological cancers

BACKGROUND

The trend toward late childbearing has made fertility preservation a major issue for women who face gynecological cancer. New techniques in assisted reproductive medicine enable conception after primary treatment of these cancers. Here, we aimed to review the efficacy and safety of assisted reproductive techniques (ART) after fertility-preserving treatment of gynaecological cancers.

METHODS

We conducted a systematic literature review of both prospective and retrospective studies in the PubMed, EMBASE, CENTRAL and SciSearch databases. In the retrieved studies, we evaluated live births, clinical pregnancies, overall survival and disease-free survival.

RESULTS

We identified many prospective and retrospective studies on this topic, but no relevant randomized clinical trials. Fertility-sparing treatments with safe oncological outcomes are feasible in endometrial, cervical and ovarian cancer cases. After cancer treatment, ART seem safe and show variable obstetrical outcomes.

CONCLUSIONS

After fertility-preserving treatment for gynaecological cancers, ART can enable pregnancy to be achieved with apparent oncological safety. The success of such procedures should directly impact clinical practice and management of those patients who require fertility-sparing treatment.

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.

Cancer in women after assisted reproductive technology

OBJECTIVE

To evaluate the risk of cancer after assisted reproductive technology (ART) therapy.

DESIGN

Longitudinal cohort study.

SETTING

Not applicable.

PATIENT(S)

New York, Texas, and Illinois residents between 2004 and 2009, treated with ART, comprising cycles of 113,226 women, including 53,859 women without prior ART treatment, who were linked to their respective state cancer registries and whose cycles were reported to the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System (SART CORS).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Diagnosis of cancer, as reported to the state cancer registry; standardized incidence ratios (SIR) and their 95% confidence intervals, comparing the observed to expected cancer cases based on age-specific cancer rates in the general population of each state.

RESULT(S)

Among the cohort of women without prior ART therapy, hazard ratios (HR) and 95% confidence intervals (CI) were calculated for treatment parameters and reproductive history factors. The mean follow-up period was 4.87 years; among women without prior ART, 450 women developed 460 cancers. Women treated with ART had a statistically significantly lower risk for all cancers (for all women: SIR 0.78; CI, 0.73-0.83; women without prior ART: SIR 0.75; CI, 0.68-0.82), breast cancer, and all female genital cancers; a non-statistically-significant lower risk for endocrine and uterine cancer; and a non-statistically-significant higher risk for melanoma and ovarian cancer. Among women without prior ART, we found no statistically significant increased HR by parity, number of cycles, cumulative follicle-stimulating hormone dosage, or cycle outcome.

CONCLUSION(S)

Women initiating ART treatment have no greater risk for developing cancer after nearly 5 years of follow-up compared with the general population and with other women treated with ART.

Does fertility treatment increase the risk of uterine cancer? A meta-analysis

An ongoing debate over the last two decades has focused on whether fertility treatment in women may lead to an increased risk of developing uterine cancer over a period of time. Uterine cancer (including mainly endometrial carcinoma and the less common uterine sarcoma) is the commonest reproductive tract cancer and the fourth commonest cancer in women in the UK. Our objective was to assess the association between fertility drugs used in the treatment of female infertility (both as an independent therapy and during in vitro fertilization cycles) and the development of uterine cancer. A literature search was performed using Medline, Embase, Cochrane Library and Google Scholar databases for comparative studies until December 2014 to investigate a clinical significance of fertility treatment on the incidence of developing uterine cancer. General and MESH search headings, as well as the 'related articles' function were applied. All comparative studies of 'fertility treatment' versus 'non-fertility treatment' reporting the incidence of uterine cancer as an outcome were included. Uterine cancer incorporated the following terms: uterine cancer, uterine body tumours, uterine sarcomas and endometrial cancers. The primary outcome of interest was the uterine cancer incidence in all 'fertility treatment' versus 'non-fertility treatment' patient groups. Secondary outcomes of interest were: (a) uterine cancer incidence in 'IVF' versus 'non-IVF' patient groups; and (b) uterine cancer incidence according to type of fertility drug used. Odds ratio was the summary statistic. Random-effects modelling, graphical exploration and sensitivity analysis were used to evaluate the consistency of the calculated treatment effect. We included six studies in our final analysis, which comprised 776,224 patients in total. Of these, 103,758 had undergone fertility treatment and 672,466 had not. There was 100% agreement between the two reviewers regarding the data extraction. All the studies contained groups that were comparable in age, although the criteria of reporting age varied. Taking all studies into account, the incidence of uterine cancer was 0.14% (150 of 103,758) in the fertility treatment group and 2.22% (14,918 of 672,466) in the non-fertility treatment group. Using the random-effect model to analyze uterine cancer incidence, this difference was not found to be of statistical significance: OR 0.78 (95% CI, 0.39-1.57). The degree of heterogeneity was high (I(2)=68%). The risk for the development of uterine and in particular endometrial cancer posed by infertility and an unopposed oestrogen state is widely recognized. The present analysis aimed to perceive whether standard fertility drugs were also a risk to future uterine cancer development. The treatment does increase the concentrations of unopposed oestrogen for a short periods of time but if successful leads to fertility. This meta-analysis points to a non-deleterious effect of fertility drugs towards the development of uterine cancer, a conclusion strongly supported by our sub-group analysis.

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.

DNA stabilization by the upregulation of estrogen signaling in BRCA gene mutation carriers

Currently available scientific evidence erroneously suggests that mutagenic weakness or loss of the BRCA1/2 genes may liberate the proliferative effects of estrogen signaling, which provokes DNA damage and genomic instability. Conversely, BRCA mutation seems to be an imbalanced defect, crudely inhibiting the upregulation of estrogen receptor expression and liganded transcriptional activity, whereas estrogen receptor-repressor functions become predominant. In BRCA-proficient cases, estrogen signaling orchestrates the activity of cell proliferation and differentiation with high safety, while upregulating the expression and DNA-stabilizing impact of BRCA genes. In turn, BRCA proteins promote estrogen signaling by proper estrogen synthesis via CYP19 gene regulation and by induction of the appropriate expression and transcriptional activity of estrogen receptors. In this exquisitely organized regulatory system, the dysfunction of each player may jeopardize genome stability and lead to severe chronic diseases, such as cancer development. Female organs, such as breast, endometrium, and ovary, exhibiting regular cyclic proliferative activity are particularly vulnerable in case of disturbances in either estrogen signaling or BRCA-mediated DNA repair. BRCA mutation carrier women may apparently be healthy or exhibit clinical signs of deficient estrogen signaling in spite of hyperestrogenism. Even women who enjoy sufficient compensatory DNA-defending activities are at risk of tumor development because many endogenous and environmental factors may jeopardize the mechanisms of extreme compensatory processes. Natural estrogens have numerous benefits in tumor prevention and therapy even in BRCA mutation carriers. There are no toxic effects even in sky-high doses and all physiologic cellular functions are strongly upregulated, while malignant tumor cells are recognized and killed in a Janus-faced manner.

Does ovarian stimulation for IVF increase gynaecological cancer risk? A systematic review and meta-analysis

The aim of this study was to evaluate whether ovarian stimulation for IVF increases the risk of gynaecological cancer, including ovarian, endometrial, cervical and breast cancers, as an independent risk factor. A systematic review and meta-analysis was conducted. Clinical trials that examined the association between ovarian stimulation for IVF and gynaecologic cancers were included. The outcomes of interest were incidence rate of gynaecologic cancers. Twelve cohort studies with 178,396 women exposed to IVF were included; 10 studies were used to analyse ovarian (167,640 women) and breast (151,702 women) cancers, and six studies were identified in the analysis of endometrial (116,672 women) and cervical cancer (114,799 women). Among these studies, 175 ovarian, 48 endometrial, 502 cervical and 866 cases of breast cancer were reported. The meta-analysis found no significant association between ovarian stimulation for IVF and increased ovarian, endometrial, cervical and breast cancer risk (odds ratio [OR] 1.06, 95% confidence interval [CI] 0.85 to 1.32; OR 0.97, 95% CI 0.58 to 1.63; OR 0.43, 95% CI 0.30 to 0.60; OR 0.69, 95% CI 0.63 to 0.76, respectively). Ovarian stimulation for IVF, therefore, does not increase the gynaecologic cancer risk, whether hormone-dependent endometrial and breast cancer or non-hormone-dependent ovarian and cervical cancer.

Menstrual and reproductive history and use of exogenous sex hormones and risk of thyroid cancer among women: a meta-analysis of prospective studies

PURPOSE

Thyroid cancer has a higher incidence in women than in men, and it has been hypothesized that hormonal factors may explain such disparity. We performed a meta-analysis of observational prospective studies to investigate the association between menstrual and reproductive variables and exogenous hormone use and the risk of thyroid cancer among women.

METHODS

We calculated summary relative risks and 95% confidence intervals (95% CI) using random effect models.

RESULTS

Overall, 5,434 thyroid cancer cases from twenty-four papers were included. Increasing age at first pregnancy/birth (SRR 1.56, 95% CI 1.01-2.42) and hysterectomy (SRR 1.43, 95% CI 1.15-1.78) were associated with thyroid cancer risk. Women that were in menopause at enrolment had a reduced thyroid cancer risk (SRR 0.79, 95% CI 0.62-1.01). No other menstrual, reproductive, and hormonal variable was associated with thyroid cancer risk.

CONCLUSIONS

Menstrual and reproductive factors may play a role in the etiology of thyroid cancer, possibly through the mediation of estrogen receptors.

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.

Clinical use of fertility agents and risk of breast cancer: a recent update for an old problem

PURPOSE OF REVIEW

Female infertility is today a very common, expanding problem and therefore restoring fertility strategies are increasing in the last few years. An association between ovarian stimulation and breast cancer risk has been hypothesized, but the question has not yet been clarified.

RECENT FINDINGS

In the last 2 years, many important studies have been published on this topic. A lot of new combinations of drugs are in experimentation and other recent drugs are already in current use, such as aromatase inhibitors. Furthermore, the data from older studies were investigated by two recent meta-analyses.

SUMMARY

Infertility affects many couples in western countries and the use of fertility stimulation techniques is widespread in the last few years, determining personal anxiety, social costs, and organizing difficulties. It is well known that one of the most important causative agents for the development of breast cancer is the proliferative activity of endogenous and exogenous female hormones. Therefore, it seems appropriate to investigate the risk of breast cancer derived from the use of hormonal therapies in infertile women. The final clarification of this question is very important so that all women can realize their dream of having children, with the certainty of not being exposed to an increased risk of breast cancer.

Thyroid cancer after in vitro fertilization: a retrospective, non-consecutive case-series analysis

Although a firm association between fertility treatment and thyroid cancer has not been established, the widespread use of IVF, as a substantial reservoir of subclinical thyroid cancer disease and evidence suggesting an estrogen-dependent behavior may render thyroid cancer patients after IVF a distinct subpopulation of particular interest. Thus, a retrospective, non-consecutive case-series analysis of patients with history of thyroid cancer after in vitro fertilization was conducted. Twelve female patients with thyroid cancer who had previously undergone IVF treatment were identified within the cohort of thyroid cancer patients followed in our institution. All cases of thyroid cancer were papillary thyroid carcinoma (PTC) on histology and median tumor size (25th and 75th percentile) was 12 mm (7 and 17 mm). Thyroid cancer was diagnosed after a median of 4 years (2 and 6 years) from the last IVF cycle and at the time of diagnosis lymph node metastases were present in five patients (42%) and distant metastases where seen in four of them. Collectively, these data suggest that an aggressive pattern of PTC might be present in this distinct subpopulation. This preliminary observation may be explained, at least in part, by the delay in the diagnosis.

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.

Fertility drugs, reproductive strategies and ovarian cancer risk

Several adverse effects have been related to infertility treatments, such as cancer development. In particular, the relationship between infertility, reproductive strategies, and risk of gynecological cancers has aroused much interest in recent years. The evaluation of cancer risk among women treated for infertility is very complex, mainly because of many factors that can contribute to occurrence of cancer in these patients (including parity status). This article addresses the possible association between the use of fertility treatments and the risk of ovarian cancer, through a scrupulous search of the literature published thus far in this field. Our principal objective was to give more conclusive answers on the question whether the use of fertility drug significantly increases ovarian cancer risk. Our analysis focused on the different types of drugs and different treatment schedules used. This study provides additional insights regarding the long-term relationships between fertility drugs and risk of ovarian cancer.

Repeated ovarian stimulation does not affect the expression level of proteins involved in cell cycle control in mouse ovaries and fallopian tubes

PURPOSE

To understand if repeated cycles (2-4 rounds) of gonadotropin stimulation could affect intracellular localization/content of proteins controlling cell cycle progression in mouse fallopian tubes (FT) and ovaries.

METHODS

FT and ovaries of estrous mice (control) and of stimulated mice were analyzed to detect Oct-3/4, Sox-2, p53, β-catenin, pAKT and cyclin D1 localization/content. Spindles and chromosome alignment were analyzed in ovulated oocytes.

RESULTS

After round 4, FT and ovaries of control and stimulated groups showed no differences in Oct-3/4, Sox-2 and β-catenin localization nor in Oct-3/4, Sox-2, p53, β-catenin and pAKT contents. Cyclin D1 level increased significantly in FT of treated mice. Oocytes number decreased meanwhile frequency of abnormal meiotic spindles increased with treatments.

CONCLUSIONS

Repetitive stimulations affected oocyte spindle morphology but did not induce changes in a set of proteins involved in cell cycle progression, usually altered in ovarian cancer. The significant increase of cyclin D1 in the FT requires further investigation.

Reproductive Factors and the Risk of Endometrial Cancer

Abstract

Endometrial cancer is the most common malignancy of women in developed countries, and its incidence is 10 times higher than in developing countries. Endometrial cancer is most common in the sixth and the seventh decades of life; thus, postmenopausal women have a higher risk of developing the disease compared with premenopausal women. The increased incidence and prevalence of endometrial cancer can be explained by the increase in life expectancy, increased caloric intake, increased obesity rates, and other changes in lifestyle and reproductive factors. Among the reproductive factors, the risk of endometrial cancer is positively correlated with a younger age at menarche and late age at menopause, infertility, null parity, age of the first child, and long-term use of unopposed estrogens for hormone replacement therapy. Protection against endometrial cancer has been detected with increase parity, the use of combined oral contraceptives, and increased age of women at last delivery. The relationship between endometrial cancer risk and miscarriage, abortion, ovulation induction drugs and in vitro fertilization is still controversial.

Triple-negative breast cancer risk in women is defined by the defect of estrogen signaling: preventive and therapeutic implications

Epidemiologic studies strongly support that triple-negative breast cancers (TNBCs) may be distinct entities as compared with estrogen receptor (ER)+ tumors, suggesting that the etiologic factors, clinical characteristics, and therapeutic possibilities may vary by molecular subtypes. Many investigations propose that reproductive factors and exogenous hormone use differently or even quite inversely affect the risk of TNBCs and ER+ cancers. Controversies concerning the exact role of even the same risk factor in TNBC development justify that the biological mechanisms behind the initiation of both TNBCs and non-TNBCs are completely obscure. To arrive at a comprehensive understanding of the etiology of different breast cancer subtypes, we should also reconsider our traditional concepts and beliefs regarding cancer risk factors. Malignancies are multicausal, but the disturbance of proper estrogen signaling seems to be a crucial risk factor for the development of mammary cancers. The grade of defect in metabolic and hormonal equilibrium is directly associated with TNBC risk for women during their whole life. Inverse impact of menopausal status or parity on the development of ER+ and ER− breast cancers may not be possible; these controversial results derive from the misinterpretation of percentage-based statistical evaluations. Exogenous or parity-associated excessive estrogen supply is suppressive against breast cancer, though the lower the ER expression of tumors, the weaker the anticancer capacity. In women, the most important preventive strategy against breast cancers – included TNBCs – is the strict control and maintenance of hormonal equilibrium from early adolescence through the whole lifetime, particularly during the periods of great hormonal changes.

Breast cancer risk after exposure to fertility drugs

In recent years, there has been an increase in the diagnosis of infertility. In industrialized countries, approximately 15% of couples experience this problem today, with a negative impact on quality of life. For this reason, assisted reproductive technologies and other treatments, finalized to overcome infertility, have become very common in clinical practice. For a long time, different ovulation-inducing drugs have been used for ovarian follicle stimulation, either as independent therapies or treatments used during in vitro fertilization cycles. Despite this long-term use, the medical care for infertility gave rise to a lively debate about the potential risk of developing breast cancer that has never been settled. Many studies have been conducted to address this question; but their results have been, and still are, contradictory. The aim of this review is to determine the potential link between the use of fertility drugs and the risk of developing breast cancer in women treated for infertility.

Circulatory estrogen level protects against breast cancer in obese women

Literary data suggest apparently ambiguous interaction between menopausal status and obesity-associated breast cancer risk based on the principle of the carcinogenic capacity of estrogen. Before menopause, breast cancer incidence is relatively low and adiposity is erroneously regarded as a protective factor against this tumor conferred by the obesity associated defective estrogen-synthesis. By contrast, in postmenopausal cases, obesity presents a strong risk factor for breast cancer being mistakenly attributed to the presumed excessive estrogen-production of their adipose-tissue mass. Obesity is associated with dysmetabolism and endangers the healthy equilibrium of sexual hormone-production and regular menstrual cycles in women, which are the prerequisites not only for reproductive capacity but also for somatic health. At the same time, literary data support that anovulatory infertility is a very strong risk for breast cancer in young women either with or without obesity. In the majority of premenopausal women, obesity associated insulin resistance is moderate and may be counteracted by their preserved circulatory estrogen level. Consequently, it is not obesity but rather the still sufficient estrogen-level, which may be protective against breast cancer in young adult females. In obese older women, never using hormone replacement therapy (HRT) the breast cancer risk is high, which is associated with their continuous estrogen loss and increasing insulin-resistance. By contrast, obese postmenopausal women using HRT, have a decreased risk for breast cancer as the protective effect of estrogen-substitution may counteract to their obesity associated systemic alterations. The revealed inverse correlation between circulatory estrogen-level and breast cancer risk in obese women should advance our understanding of breast cancer etiology and promotes primary prevention measures. New patents recommend various methods for the prevention and treatment of obesity-related systemic disorders and the associated breast cancer.

Risk of ovarian cancer in women treated with ovarian stimulating drugs for infertility

BACKGROUND

The use of assisted reproductive techniques is increasing, but the possible link between fertility drugs and ovarian cancer remains controversial.

OBJECTIVES

To evaluate the risk of ovarian cancer in women treated with ovulation stimulating drugs for subfertility.

SEARCH METHODS

We searched for published and unpublished observational studies from 1990 to February 2013. The following databases were used: the Cochrane Gynaecological Cancer Collaborative Review Group's Trial Register, Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 1, MEDLINE (to February week 4 2013), EMBASE (to 2013 week 09) and databases of conference abstracts. We also scanned reference lists of retrieved articles. The search was not restricted by language of publication.

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs) and non-randomised studies, and case series including more than 30 participants, reporting on women with exposure to ovarian stimulating drugs for treatment of subfertility and histologically confirmed borderline or invasive ovarian cancer.

DATA COLLECTION AND ANALYSIS

At least two review authors independently conducted eligibility and 'Risk of bias' assessment, and extracted data. We grouped studies based on the fertility drug used for two outcomes: borderline ovarian tumours and invasive ovarian cancer. We expressed findings as adjusted odds ratio (OR), risk ratio (RR), hazard ratio (HR) or crude OR if adjusted values were not reported and standardised incidence ratio (SIR) where reported. We conducted no meta-analyses due to expected methodological and clinical heterogeneity.

MAIN RESULTS

We included 11 case-control studies and 14 cohort studies, which included a total of 182,972 women.Seven cohort studies showed no evidence of an increased risk of invasive ovarian cancer in subfertile women treated with any drug compared with untreated subfertile women. Seven case-control studies showed no evidence of an increased risk, compared with control women of a similar age. Two cohort studies reported an increased incidence of invasive ovarian cancer in subfertile women treated with any fertility drug compared with the general population. One of these reported a SIR of 5.0 (95% confidence interval (CI) 1.0 to 15), based on three cancer cases, and a decreased risk when cancer cases diagnosed within one year of treatment were excluded from the analysis(SIR 1.67, 95% CI 0.02 to 9.27). The other cohort study reported an OR of 2.09 (95% CI 1.39 to 3.12), based on 26 cases.For borderline ovarian tumours, exposure to any fertility drug was associated with a two to three-fold increased risk in two case-control studies. One case-control study reported an OR of 28 (95% CI 1.5 to 516), which was based on only four cases. In one cohort study, there was more than a two-fold increase in the incidence of borderline tumours compared with the general population (SIR 2.6, 95% CI 1.4 to 4.6) and in another the risk of a borderline ovarian tumour was HR 4.23 (95% CI 1.25 to 14.33) for subfertile women treated with in vitro fertilisation (IVF) compared with a non-IVF treated group with more than one year of follow-up.There was no evidence of an increased risk in women exposed to clomiphene alone or clomiphene plus gonadotrophin, compared with unexposed women. One case-control study reported an increased risk in users of human menopausal gonadotrophin (HMG)(OR 9.4, 95% CI 1.7 to 52). However, this estimate is based on only six cases with a history of HMG use.

AUTHORS' CONCLUSIONS

We found no convincing evidence of an increase in the risk of invasive ovarian tumours with fertility drug treatment. There may be an increased risk of borderline ovarian tumours in subfertile women treated with IVF. Studies showing an increase in the risk of ovarian cancer had a high overall risk of bias, due to retrospective study design, lack of accounting for potential confounding and estimates based on a small number of cases. More studies at low risk of bias are needed.

IVF and breast cancer: a systematic review and meta-analysis

BACKGROUND

The effects of controlled ovarian hyperstimulation (COH) for IVF in terms of breast cancer risk remain controversial, despite the hormone-dependent nature of the latter.

METHODS

Eligible studies up to 15 February 2013 were identified and pooled effect estimates for relative risk (RR) were calculated separately for the investigations using the general population and those using infertile women, as a reference group. Fixed- or random-effects models were implemented and subgroup analyses were performed, as appropriate.

RESULTS

Eight cohort studies were synthesized, yielding a total cohort size of 1,554,332 women among whom 14,961 incident breast cancer cases occurred, encompassing 576 incident breast cancer cases among women exposed to IVF. No significant association between IVF and breast cancer was observed either in the group of studies treating the general population (RR = 0.91, 95% confidence interval (CI): 0.74-1.11) or infertile women (RR = 1.02, 95% CI: 0.88-1.18), as a reference group. Of note were the marginal associations, protective for pregnant and/or parous women after IVF (pooled effect estimate = 0.86, 95% CI: 0.73-1.01) and adverse for women <30 years at first IVF treatment (pooled effect estimate = 1.64, 95% CI: 0.96-2.80).

CONCLUSIONS

At present, COH for IVF does not seem to impart increased breast cancer risk. Longer follow-up periods, comparisons versus infertile women, subgroup analyses aiming to trace vulnerable subgroups, adjustment for various confounders and larger informative data sets are needed before conclusive statements for the safety of the procedure are reached.

Hormonal and surgical treatments for endometriosis and risk of epithelial ovarian cancer

OBJECTIVE

Whether hormonal or surgical treatment of endometriosis is associated with risk of epithelial ovarian cancer.

DESIGN

Nested case-control study.

SETTING

Sweden.

POPULATION

All women with a first-time discharge diagnosis of endometriosis in 1969-2007 were identified using the National Swedish Patient Register and constituted our study base.

METHODS

By linkage to the National Swedish Cancer Register we identified all women diagnosed with epithelial ovarian cancer at least one year after the endometriosis diagnosis (cases). Two controls per case with no ovarian cancer before the date of cancer diagnosis of the case were randomly selected from the study base and matched for year of birth. Two-hundred-and-twenty cases and 416 controls entered the study. Information on hormonal and surgical treatments and other reproductive factors was extracted from medical records according to pre-specified protocols. Conditional logistic regression was used for all calculations.

MAIN OUTCOME MEASURES

Crude and adjusted odds ratios (OR) with 95% confidence intervals (CI) for all hormonal as well as surgical treatments.

RESULTS

There was a significant association between one-sided oophorectomy, as well as for radical extirpation of all visible endometriosis, and ovarian cancer risk in both univariate analyses (crude OR 0.42, 95% CI 0.28-0.62 and OR 0.37, 95% CI 0.25-0.55, respectively) and multivariate analyses (adjusted OR 0.19, 95% CI 0.08-0.46 and OR 0.30, 95% CI 0.12-0.74, respectively).

CONCLUSIONS

One-sided oophorectomy as well as radical extirpation of all visible endometriosis is protective against later development of ovarian cancer.