The possible association between in vitro fertilization treatments and cancer development

In-Vitro Fertilization Impact on the Risk of Breast Cancer: A Review Article

Background

Due to the increasing prevalence of infertility, the number of referrals to infertility treatment centers has also increased. Nowadays, assisted reproductive technology (ART), including in vitro fertilization (IVF), is a treatment for infertility or genetic problems. Considering the possible consequences of this method among women undergoing in vitro fertilization (IVF) and kids conceived by IVF, extensive research has been conducted in this regard.

Methods

Overall, 100 articles were entered into the study, and relevant articles were searched and extracted from PubMed, Springer, and Google Scholar databases. In IVF procedure, medications such as Clomiphene citrate and gonadotropins are used to stimulate and mature follicles and thus increase ovulation.

Results

There are conflicting opinions on this issue. Some findings report a slight increase in cancer risk for hormone-sensitive cancers including breast cancer. The long-term use of IVF medications can increase estrogen hormones and cause excessive expression of genes, resulting in an increased risk of breast cancer, which is one of the most frequent cancers among women.

Conclusion

There are some risks to be aware of, which followed the hypothesis that long IVF treatment process may lead to breast cancer among IVF candidates. Furthermore, the risk of breast cancer may be increased in those women with a positive family history and related inherited genes. Therefore, women candidates for IVF should be informed of the probable implications of the reproductive therapy techniques.

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The original review included published and unpublished observational studies from 1990 to February 2013.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.

Breast Cancer and Ovulation Induction Treatments

BACKGROUND

This study was performed to determine whether the use of ovulation induction drugs in treatment of infertility have a significant effect on the risk of breast cancer.

PATIENTS AND METHODS

This case control study (928 cases, 928 controls), was performed in the gynecology and oncology clinics of Shahid Beheshti University of Medical Sciences between 2011 and 2013. Data were collected via in-person interviews using a questionnaire, which included demographic and gynecologic information. Statistical analysis was performed using SPSS statistics software version 20 (IBM Corp).

RESULTS

The use of ovulation induction drugs was not significantly associated with an increased risk of breast cancer (odds ratio [OR], 1.13; 95% confidence interval [CI], 0.7-1.855) among women with infertility (OR, 1.28; 95% CI, 0.8-1.95).

CONCLUSION

We observed no statistically significant relationship between infertility and ovulation induction drugs with the risk of breast cancer, except for significant increases in the risk of breast cancer among patients who had used fertility drugs for >6 months.

Immunocytogenetic effects of gonadotropin releasing hormone analogue: Triptorelin Pamoate (Decapeptyl ®) during in vitro fertilization treatment

In this study, the immunocytogenetic effects of Decapeptyl ® (Triptorelin Pamoate) were assessed in the peripheral blood lymphocytes of females undergoing in vitro fertilization (IVF) treatment. Blood samples were taken from 34 females (23 treated and 11 controls), cultured and examined for sister chromatid exchanges (SCE) and cell replication index (CRI). The SCE frequency increased around ovulation time in the controls, and around the time of human chorionic gonadotropin administration in the IVF group. However, the SCE rate was significantly higher in the latter group. Furthermore, the white blood cells (WBC) count was significantly higher on the day of ovum pick up compared to the day preceding luteinizing hormone (LH) and follicle stimulating hormone (FSH) treatment. Similar observations were recorded with respect to phagocytic activity tested by nitroblue tetrazolium (NBT) assay. The nitric oxide production abilities of macrophages were not significantly changed in the LH, FSH-treated group relative to its control. Finally, the 50% complement hemolytic activity (CH50) assay results indicated that Decapeptyl lacks a significant potential to affect the complement system.

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.

The determination of possible genetic damage to women undergoing in vitro fertilization due to infertility caused by the male factor

In this study, we aimed at determining possible genetic damage to women who were exposed to in vitro fertilization (IVF) due to infertility with male factor. Four different genotoxicity tests were used in human lymphocytes in this study with regard to chromosomal aberration (CA), sister chromatid exchange (SCE), micronucleus (MN), and comet tests. There was a statistically significant increase in sister chromatid exchange (SCE) test in the study group compared with the control group. In addition, a higher rate of MN frequency was determined only in the 21–30 age range study group compared with the control group in the same age range. On the other hand, MN frequency did not differ significantly between the control and total study groups. In addition, there was no significant difference between the control group and the study group in terms of mitotic (MI), replication (RI), and nuclear division (NDI) indices. Furthermore, there was no statistically significant increase for chromosomal aberration and DNA damage to the study groups. Our results showed that in vitro fertilization treatments have a weak risk at the genetic level in cultured human lymphocytes.

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.

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.

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

BACKGROUND

Although fertility drugs stimulate ovulation and raise estradiol levels, their effect on breast cancer risk remains unresolved.

METHODS

An extended follow-up was conducted among a cohort of 12,193 women evaluated for infertility between 1965 and 1988 at five U.S. sites. Follow-up through 2010 was achieved for 9,892 women (81.1% of the eligible population) via passive as well as active (questionnaires) means. Cox regression determined HRs and 95% confidence intervals (CI) for fertility treatments adjusted for breast cancer risk factors and causes of infertility.

RESULTS

During 30.0 median years of follow-up (285,332 person-years), 749 breast cancers were observed. Ever use of clomiphene citrate among 38.1% of patients was not associated with risk (HR = 1.05; 95% CI, 0.90-1.22 vs. never use). However, somewhat higher risks were seen for patients who received multiple cycles, with the risk for invasive cancers confirmed by medical records being significantly elevated (HR = 1.69; 95% CI, 1.17-2.46). This risk remained relatively unchanged after adjustment for causes of infertility and multiple breast cancer predictors. Gonadotropins, used by 9.6% of patients, mainly in conjunction with clomiphene, showed inconsistent associations with risk, although a significant relationship of use with invasive cancers was seen among women who remained nulligravid (HR = 1.98; 95% CI, 1.04-3.60).

CONCLUSIONS

Although the increased breast cancer risk among nulligravid women associated with gonadotropins most likely reflects an effect of underlying causes of infertility, reasons for the elevated risk associated with multiple clomiphene cycles are less clear.

IMPACT

Given our focus on a relatively young population, additional evaluation of long-term fertility drug effects on breast cancer is warranted.

Very young breast cancer in a referral center in Tehran, Iran; review of 55 cases aged 25 or less throughout 33 years

BACKGROUND

Breast cancer is mostly the disease of postmenopausal women but very young affected women are seen more than occasionally in developing countries. We reviewed our cases of very young breast cancer in order to help in better understanding of such cases.

MATERIALS AND METHODS

The records of patients 25 years of age or less who had been admitted for breast cancer surgery in the Cancer Institute of Tehran from 1979 to 2012 were reviewed and relevant data were extracted.

RESULTS

From 5,265 cases of breast cancer, 62 patients had 25 years of age or less. There were 55 cases of breast adenocarcinoma, all female. More than 78% of the patients had presented with a palpable mass, the family history was positive in 2% of cases, and about 94% of the histologies were invasive ductal carcinoma. Gestational breast cancer constituted 10% of the cancers; another 10%were bilateral. The median size of the tumors was 5.72 centimeters, 63.2% of them had axillary lymphatic involvement, and more than half were negative for hormone receptors.

CONCLUSIONS

Our study shows an incidence of 1.17% for very young breast cancer and a 10% rate of bilaterality which probably warrants special guidelines for contralateral screening. Cancer stage and features were poor in comparison with breast cancer in all ages.

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.

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.

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.

Meta-Analysis on the Possible Association Between In Vitro Fertilization and Cancer Risk

Objective

We aimed to examine the association between in vitro fertilization (IVF) and risk of cancers through conducting a meta-analysis of cohort studies.

Methods

Relevant studies were identified by using PubMed, ISI Web of knowledge, and Scopus through March 2012. Reference lists from retrieved articles were also reviewed. We included historical cohort studies that reported relative risks (RRs) with 95% confidence intervals (CIs) for the association between IVF and cancer risk. Both fixed- and random-effects models were used to calculate the summary risk estimates.

Results

Eight cohort studies involving 746,455 participants were included in this meta-analysis. The overall combined RRs for women with IVF treatment were 0.99 (95% CI, 0.74–1.32) for all-site cancer, 1.59 (95% CI, 1.24–2.03) for ovarian cancer, 0.89 (95% CI, 0.79–1.01) for breast cancer, and 1.07 (95% CI, 0.45–2.55) for cervical cancer. A beneficial effect was shown in the subgroup of breast cancer meta-analysis compared with women who gave birth (RR, 0.79; 95% CI, 0.65–0.95). Excess risk of ovarian cancer was still observed when analyses were restricted to studies with less than 8 years of follow-up (RR, 2.35; 95% CI, 1.03–5.37) and studies including cancer cases diagnosed within 1 year of the IVF treatment (RR, 1.71; 95% CI, 1.22–2.40). No evidence of substantial publication bias was observed.

Conclusions

This meta-analysis suggests that there is no significant association between IVF and cancer risk. A possible beneficial effect was shown in the subgroup of breast cancer meta-analysis. Excess risk of ovarian cancer was observed in the analysis of all the studies and subgroups. Special attention should be made to women who may be diagnosed with cancer during or shortly after IVF treatment. Studies of high methodological quality with larger population and longer follow-up are required to provide more evidences for a better understanding of the association.

Infertility treatment and the risk of cancer

BACKGROUND

A possible correlation between hormonal stimulation during treatment of infertility and the risk of cancer of the breast, the ovaries, the cervix or the uterus has been investigated in a number of epidemiological studies. The purpose of this article is to review the relevant literature and summarise the findings. KNOWLEDGE BASE: This review article is based on literature searches in the databases MEDLINE, Cochrane and EMBASE.

RESULTS

No studies showed a specific general correlation between hormonal ovulatory stimulation used as pre-treatment to assisted fertilisation and an increased risk of cancer of the breast, the ovaries, the cervix or the uterus. Most studies detected no increased risk. Some studies, however, showed an increased risk of cancer among certain sub-groups, such as women who have received repeated treatment with clomiphene citrate.

INTERPRETATION

On the basis of the studies reviewed, the conclusions are ambiguous. It is therefore necessary to monitor the long-term effects of infertility treatment on women's health. Further good-quality large-scale population studies are necessary, with longer follow-up periods and better adjustment for confounding factors.

Are infertility treatments a potential risk factor for cancer development? Perspective of 30 years of follow-up

The aim of the present study was to evaluate the possible risk for cancer development in infertile women with over 30 years of follow-up. Cancer development was assessed through linkage with the National Cancer Registry updated to 31 December 2005 in a cohort of 2431 women who were treated for infertility at the Sheba Medical Center in Israel during the period 1964-1974 and contributed more than 84,000 women years of follow-up. Standardized incidence ratios (SIR) were calculated between the observed cancer cases and the expected cancer rates in the general population. The mean age at the end of follow-up was 62.7 years. Eighteen cases of ovarian cancer were observed as compared to 18.1 expected (SIR = 1.0; 95% CI = 0.59-1.57). For breast cancer, 153 cases were observed as compared to 131.9 expected (SIR = 1.16; 95% CI = 0.98-1.36), and for endometrial cancer, 30 cases were observed as compared to 17.8 expected cases (SIR = 1.69; 95% CI = 1.14-2.41). No excess risk associated with exposure to gonadotropins was observed. Infertility was found to be associated with significant increased risk for endometrial cancer and borderline increased risk for breast cancer. Ovarian cancer risk was not found to be elevated. No significant excess risk was associated with treatment with ovulation induction.

Fertility drugs and young-onset breast cancer: results from the Two Sister Study

BACKGROUND

Fertility drugs stimulate hyperovulation, which may have implications for breast cancer. We examined the association between use of fertility drugs (clomiphene citrate [CC] and follicle-stimulating hormone [FSH]) and subsequent risk of young-onset (<50 years at diagnosis) breast cancer.

METHODS

We conducted the Two Sister Study, a sister-matched case-control study, by enrolling 1422 women between September 2008 and December 2010, who were younger than age 50 years at diagnosis with breast cancer and were enrolled within 4 years of diagnosis, and 1669 breast cancer-free control sisters from the Sister Study. Participants reported their use of fertility drugs (CC and FSH) and ever-users reported whether a pregnancy had resulted that lasted 10 or more (10+) weeks. Conditional logistic regression was used to estimate confounder-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for fertility drug use with or without conception of a 10+ week pregnancy.

RESULTS

A total of 288 participants reported having used ovulation-stimulating drugs (193 CC only, 29 FSH only, and 66 both). Overall, women who had used fertility drugs showed a non-statistically significantly decreased risk of breast cancer, compared with nonusers (OR = 0.82, 95% CI = 0.63 to 1.08). Women who had used fertility drugs but had not conceived a 10+ week pregnancy under treatment showed a statistically significantly decreased risk of breast cancer compared with nonusers (OR = 0.62, 95% CI = 0.43 to 0.89). Women who had used fertility drugs and conceived a 10+ week pregnancy under treatment showed a statistically significantly increased risk of breast cancer compared with unsuccessfully treated women (OR = 1.82, 95% CI = 1.10 to 3.00), although their risk was not increased compared with women who had not used fertility drugs (OR = 1.13, 95% CI = 0.78 to 1.64).

CONCLUSIONS

In the absence of a 10+ week pregnancy under treatment, exposure to ovulation-stimulating fertility drugs was associated with reduced risk of young-onset breast cancer. This apparent association was absent in women who conceived a 10+ week pregnancy under treatment, for whom risk was higher than that of unsuccessfully treated women, but similar to that of untreated women.

In vitro fertilization and breast cancer: is there cause for concern?

OBJECTIVE

To examine the incidence rate of breast cancer in a cohort of women undergoing treatment for infertility, comparing the rate in women who had in vitro fertilization (IVF) with those who did not.

DESIGN

Population-based cohort study using linked hospital and registry data.

SETTING

Hospital.

PATIENT(S)

All women aged 20-44 years seeking hospital investigation and treatment for infertility in Western Australia during the period 1983-2002 (n = 21,025).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Hazard ratios (HRs) for breast cancer.

RESULT(S)

There was no overall increase in the rate of breast cancer in women who had IVF (HR 1.10, 95% confidence interval [CI] 0.88-1.36), but there was an increased rate in women who commenced IVF at a young age. Women who commenced hospital infertility treatment at 24 years and required IVF had an unadjusted HR of breast cancer of 1.59 (95% CI 1.05-2.42) compared with women of the same age who had infertility treatment but no IVF. When adjusted for late age at first delivery, which is associated with an increased rate of breast cancer, and delivery of twins and higher-order multiples, which is associated with a decreased rate of breast cancer, the HR remained elevated at 1.56 (95% CI 1.01-2.40). Hazard ratios were not elevated in women who commenced treatment at age 40 and required IVF (adjusted HR 0.87, 95% CI 0.62-1.22).

CONCLUSION(S)

Commencing IVF treatment at a young age is associated with an increased rate of breast cancer.

Fertility drugs and the risk of breast and gynecologic cancers

The evaluation of cancer risk among patients treated for infertility is complex, given the need to consider indications for use, treatment details, and the effects of other factors (including parity status) that independently affect cancer risk. Many studies have had methodologic limitations. Recent studies that have overcome some of these limitations have not confirmed a link between drug use and invasive ovarian cancers, although there is still a lingering question as to whether borderline tumors might be increased. It is unclear whether this merely reflects increased surveillance. Investigations regarding breast cancer risk have produced inconsistent results. In contrast, an increasing number of studies suggest that fertility drugs may have a special predisposition for the development of uterine cancers, of interest given that these tumors are recognized as particularly hormonally responsive. Additional studies are needed to clarify the effects on cancer risk of fertility drugs, especially those used in conjunction with in vitro fertilization. Because many women who have received such treatments are still relatively young, further monitoring should be pursued in large well-designed studies that enable assessment of effects within a variety of subgroups defined by both patient and disease characteristics.

Risk of borderline and invasive ovarian tumours after ovarian stimulation for in vitro fertilization in a large Dutch cohort

BACKGROUND

Long-term effects of ovarian stimulation for IVF on the risk of ovarian malignancies are unknown.

METHODS

We identified a nationwide historic cohort of 19,146 women who received IVF treatment in the Netherlands between 1983 and 1995, and a comparison group of 6006 subfertile women not treated with IVF. In 1997-1999, data on reproductive risk factors were obtained from 65% of women and data on subfertility (treatment) were obtained from the medical records. The incidence of ovarian malignancies (including borderline ovarian tumours) through 2007 was assessed through linkage with disease registries. The risk of ovarian malignancies in the IVF group was compared with risks in the general population and the subfertile comparison group.

RESULTS

After a median follow-up of 14.7 years, the risk of borderline ovarian tumours was increased in the IVF group compared with the general population [standardized incidence ratio (SIR) = 1.76; 95% confidence interval (CI) = 1.16-2.56]. The overall SIR for invasive ovarian cancer was not significantly elevated, but increased with longer follow-up after first IVF (P = 0.02); the SIR was 3.54 (95% CI = 1.62-6.72) after 15 years. The risks of borderline ovarian tumours and of all ovarian malignancies combined in the IVF group were significantly increased compared with risks in the subfertile comparison group (hazard ratios = 4.23; 95% CI = 1.25-14.33 and 2.14; 95% CI = 1.07-4.25, respectively, adjusted for age, parity and subfertility cause).

CONCLUSIONS

Ovarian stimulation for IVF may increase the risk of ovarian malignancies, especially borderline ovarian tumours. More large cohort studies are needed to confirm these findings and to examine the effect of IVF treatment characteristics.

Fertility drugs and ovarian cancer risk: a critical review of the literature

There is evidence that medications used for ovarian stimulation and in vitro fertilization may be associated with ovarian cancer. In this review, we attempt to describe this relationship according to the most recent epidemiologic data and to present the possible mechanisms on the molecular level that could potentially explain this correlation. Currently there is no proven relationship between any type of ovarian cancer and drugs used for infertility treatment. Overall, infertile women have increased risk for ovarian malignancies. Nulligravidas that received treatment are at increased risk for ovarian malignancy as compared to women that conceived after treatment. More studies with the appropriate statistical power and follow-up time, as well as with better adjustment for confounding factors, which coexist in infertile patients, are required to evaluate accurately the long-term effects of these drugs and procedures.

Endometriosis, in vitro fertilisation and the risk of gynaecological malignancies, including ovarian and breast cancer

There is evidence that endometriosis as well as drugs used in the process of in vitro fertilisation appear to associate with increased risk for gynaecological cancer. In this review, we attempt to describe this relationship according to the most recent epidemiologic data and to present the possible mechanisms on the molecular level that could potentially explain this correlation. There are data to support that ovarian endometriosis could have the potential for malignant transformation. Epidemiologic and genetic studies support this notion. It seems that endometriosis is associated with specific types of ovarian cancer (endometrioid and clear cell). There is no clear association between endometriosis and breast or endometrial cancer. More studies are needed to establish the risk factors that may lead to malignant transformation of this condition and to identify predisposed individuals who may require closer surveillance. Currently, there is no proven relationship between any type of gynaecological cancer and drugs used for infertility treatment. In principle, infertile women have increased risk for gynaecologic malignancies. Nulligravidas who received treatment are at increased risk for malignancy compared with women who had conceived after treatment. There is limited evidence that clomiphene citrate use for more than six cycles or 900mg or treatment of women over the age of 40 could increase their risk for ovarian and breast cancer. More studies with the appropriate statistical power and follow-up time are required to evaluate accurately the long-term effects of these drugs and procedures.

Use of fertility drugs and risk of ovarian cancer: Danish Population Based Cohort Study

OBJECTIVE

To examine the effects of fertility drugs on overall risk of ovarian cancer using data from a large cohort of infertile women.

DESIGN

Population based cohort study.

SETTING

Danish hospitals and private fertility clinics.

PARTICIPANTS

54,362 women with infertility problems referred to all Danish fertility clinics during 1963-98. The median age at first evaluation of infertility was 30 years (range 16-55 years), and the median age at the end of follow-up was 47 (range 18-81) years. Included in the analysis were 156 women with invasive epithelial ovarian cancer (cases) and 1241 subcohort members identified in the cohort during follow-up in 2006.

MAIN OUTCOME MEASURE

Effect of four groups of fertility drugs (gonadotrophins, clomifene citrate, human chorionic gonadotrophin, and gonadotrophin releasing hormone) on overall risk of ovarian cancer after adjustment for potential confounding factors.

RESULTS

Analyses within cohort showed no overall increased risk of ovarian cancer after any use of gonadotrophins (rate ratio 0.83, 95% confidence interval 0.50 to 1.37), clomifene (1.14, 0.79 to 1.64), human chorionic gonadotrophin (0.89, 0.62 to 1.29), or gonadotrophin releasing hormone (0.80, 0.42 to 1.51). Furthermore, no associations were found between all four groups of fertility drugs and number of cycles of use, length of follow-up, or parity.

CONCLUSION

No convincing association was found between use of fertility drugs and risk of ovarian cancer.

Effect of desire to have a baby on risk acceptance in Turkish infertile women

The aim of this study was to assess whether the desire to escape the psychological condition created by infertility (to have a baby) affected risk-taking behavior, with the possible relationship between ovarian cancer and infertility as the "accepted risk" to overcome infertility. 229 infertile and 204 fertile women who were patients at the Gulhane Military Medical Academy were administered a semistructured questionnaire. Increased ovarian cancer risk was accepted by 67.2% of the infertile women in order to have baby. There was no significant relation between the woman's age, duration of infertility, knowledge of the preventability and curability of ovarian cancer, or acceptable risk. These results indicate the importance to Turkish women of overcoming infertility.

Infertility as a cancer risk factor - a review

Ovarian, endometrial and breast cancers are associated with several risk factors, such as low parity, infertility, early age at menarche, and late age at menopause. Frequently most of these risk factors coexist in infertile patients and some studies suggested that the different infertility causes can be involved in cancer risk development. In particular case-control and cohort studies investigated the possible role of ovulatory disorders, endometriosis and unexplained infertility in increasing the risk of this disease. Most studies have shown no overall increased risk in invasive ovarian cancer in subfertile patients, although nulliparity has been consistently associated with increased rates of ovarian tumor, in particular with borderline and endometrioid cancers in patients with a history of endometriosis. Different studies reported that infertile women are not at risk for breast cancer. However, women affected by infertility may be more at risk for endometrial cancer, particularly if affected by ovulatory disorders. Moreover, infertility is now often treated with medical devices that could by themselves modify the hormonal environment and be cofactors in the cellular changes towards cancer development. However, although early studies suggested that infertility medications were associated to increased risk in ovarian cancer, subsequent studies have been mainly reassuring, although suggesting that type and duration of medical treatment can increase the malignancy risk. An increased risk of endometrial cancer in patients undergoing infertility treatment has been reported, as expected by the similar structure shared by clomiphene and tamoxiphene. Since breast cancer is widely recognized as having a hormonal etiology, a possible role of fertility medications to promote cancer has been hypothesized. However, many large studies were not able to find an associated risk of breast cancer. In conclusion, nowadays, firm answers about the precise effects of infertility and its treatment on cancer risk are not available but findings are generally reassuring. Further studies about fertility drug treatments on larger populations may offer in the future longer follow-up and more precise data with better adjustments for confounding factors.

Beginning IVF treatments after age 30 increases the risk of breast cancer: results of a case-control study

The long-term risks of in vitro fertilization (IVF) treatment remain unclear. This study was designed to determine breast cancer risk factors in women who underwent IVF, and to establish characteristics of these tumors. Records of 7,162 consecutive women who underwent IVF at a single center between 1984 and 2002 were linked with the Israel Cancer Registry to identify women who developed breast cancer. IVF-related parameters were compared between 28 breast cancer patients who had undergone IVF (IVF BC) and for whom complete IVF data were available with 140 women who underwent IVF and did not develop breast cancer (IVF non-BC). Tumor parameters were compared between 38 patients who developed breast cancer after IVF and 114 age-matched breast cancer patients who did not undergo IVF (non-IVF BC). Age over 30 at the time of first IVF treatment, even after controlling for age at first birth, was the only parameter significantly associated with increased breast cancer risk (RR = 1.24, p = 0.02, 95% CI = 1.03-1.48). There were no differences between IVF-BC and IVF non-BC patients in all other IVF-related parameters. The only statistically significant difference in tumors developing in IVF-BC patients compared with non-IVF BC patients was in grade distribution, particularly for grade II tumors. However, the significance of such a difference is unclear. Women who start IVF after the age of 30 appear to be at increased risk of developing breast cancer. The characteristics of breast tumors in women who underwent IVF are no different than in patients without previous exposure to IVF.

In vitro fertilisation policy in Israel and women's perspectives: the more the better?

Israel offers nearly full funding for in vitro fertilisation (IVF) to any Israeli woman irrespective of her marital status or sexual orientation, until she has two children with her current partner. Consequently, Israeli women are the world's most intensive consumers of IVF. This 2006 study explored the perceptions of Israeli IVF patients about the treatment and their experiences, probing possible links between state policy and women's choices and health. Israeli women (n=137), all currently undergoing IVF, were invited to fill out questionnaires. The questionnaires were delivered in five IVF centres by university nursing students or by the clinics' nurses. Most women were optimistic they would become pregnant, and described the treatment as having modest or no negative effects on their lives. They expressed a sweeping commitment to IVF, which they were willing to repeat "as many times as needed". At the same time, the majority appeared to have very partial treatment-related knowledge and marginalised side effects, even though they had experienced some themselves. We interpret the observed favourable image of IVF as closely related to the encouragement implied in the extensive state funding of IVF and in the Jewish Israeli tradition of pronatalism, which may account for the virtual absence of critical public debate on the subject.

Risk of breast cancer and gynecologic cancers in a large population of nearly 50,000 infertile Danish women

Infertility is considered to influence the risk of breast cancer and gynecologic cancers. To assess this association, the authors used data from a large cohort of 54,362 women with a diagnosis of infertility who were referred to Danish fertility clinics between 1963 and 1998. Through 2003, 1,975 cancers were identified by linkage to the Danish Cancer Registry. Cancer risk was assessed through standardized incidence ratios (SIRs) and corresponding 95% confidence intervals, using general and parity-specific cancer incidence rates in the general population of Denmark as a reference. After adjustment for parity status, significantly increased SIRs were observed for breast (SIR = 1.08, 95% confidence interval: 1.01, 1.16) and ovarian (SIR = 1.46, 95% confidence interval: 1.24, 1.71) cancer. The risk of breast cancer increased with follow-up time. Similar risk patterns were observed for the different histologic types of breast cancer and all nonmucinous types of ovarian cancer, whereas the risk of mucinous ovarian cancers seemed not to be increased. These data thus suggest higher risks of breast and ovarian cancer among infertile women. However, since these results could not distinguish the effects of underlying infertility from the effects of fertility treatment, additional studies are needed to disentangle the effects of these two factors.

Maternal morbidity and mortality in in-vitro fertilization

Pregnancies following in-vitro fertilization (IVF) are known to be at increased risk of a number of pregnancy- and delivery-related complications when compared with non-IVF pregnancies. Most of these complications seem to be due to underlying fertility problems. Ovarian stimulation carries a marked risk for two serious conditions - ovarian torsion and ovarian hyperstimulation syndrome - both of which are relatively rare. Although some common pregnancy complications show an up to five times increased risk over non-IVF pregnancies, the absolute frequencies are still low for most of these conditions. However, an increased risk of placenta praevia might be to some extent due to the IVF procedure. No long-terms effects on cancer risk or mortality can be linked to the IVF procedure, although follow-up time is still relatively short.

The possible association between IVF and breast cancer incidence

BACKGROUND

The possible association between ovulation-inducing drugs and breast cancer development has been debated. Our aim was to evaluate the incidence of breast cancer in a cohort of women exposed to in vitro fertilization (IVF).

METHODS

A retrospective cohort analysis was performed by linkage of the computerized database of all women treated at the IVF Unit at Assaf Harofeh Medical Center between 1986 and 2003, and the Israeli National Cancer Registry. The standardized incidence ratio (SIR) was computed as the ratio between the observed number of breast cancer cases and the expected cases, adjusted for age and continent of birth, in the general population. Tumor characteristics of the IVF patients were studied by reviewing original medical records.

RESULTS

35 breast carcinomas were diagnosed among 3,375 IVF-treated women, compared to 24.8 cases expected (SIR = 1.4; 95% CI 0.98-1.96). Age >or=40 years at IVF treatment (SIR = 1.9; 95% CI 0.97-3.30), hormonal infertility (SIR = 3.1; 95% CI 0.99-7.22), and >or=4 IVF cycles (SIR = 2.0; 95% CI 1.15-3.27) were found to be risk factors to develop breast cancer compared to the general population. Multivariate analysis revealed that women who underwent >or=4 IVF cycles compared to those with one to three cycles were at risk to develop breast cancer, although not significantly (SIR = 1.9; 95% CI 0.95-3.81). Of IVF-treated women 85% had ER(+) tumors and 29% had positive family history.

CONCLUSIONS

A possible association between IVF therapy and breast cancer development was demonstrated, especially in women >or=40 years of age. These preliminary findings need to be replicated in other cohort studies.

Long-term effects of ovulation-stimulating drugs on cancer risk

Although nulliparity has been extensively related to the risk of ovarian, breast and endometrial cancers, with many studies showing the relationship largely attributable to infertility, treatment effects on cancer risk are poorly understood. Two early studies raised substantial concern when ovulation-stimulating drugs were linked with large increases in ovarian cancer, supporting the notion of an important aetiological role of incessant ovulation. Subsequent studies have been mainly reassuring, although some have suggested possible risk increases among nulligravid women, those with extensive follow-up, and those developing borderline tumours. Results regarding effects of fertility drugs on breast cancer risk are conflicting, with some showing no associations and others demonstrating possible risk increases, although for varying subgroups. In contrast, endometrial cancer results are more consistent, with two recent studies showing increased risks related to clomiphene usage. This is of interest given that clomiphene is structurally similar to tamoxifen, a drug extensively linked with this cancer. Given the recent marketing of fertility drugs and the fact that exposed women are only beginning to reach the cancer age range, further follow-up is necessary. This will also be important to fully resolve effects of exposures such as gonadotrophins, used more recently in conjunction with IVF.

Risk of Breast Cancer After Exposure to Fertility Drugs: Results from a Large Danish Cohort Study

BACKGROUND

Few epidemiologic studies have examined the association between fertility drugs and breast cancer risk, and results have been contradicting. Using data from the largest cohort of infertile women to date, the aim of this study was to examine the effects of fertility drugs on breast cancer risk overall and according to histologic subtypes.

METHOD

A cohort of 54,362 women with infertility problems referred to all Danish fertility clinics between 1963 and 1998 was established. A detailed data collection, including information of type and amount of treatment, was conducted. We used case-cohort techniques to calculate rate ratios (RR) of breast cancer associated with use of five groups of fertility drugs, after adjustment for parity status.

RESULTS

Three hundred thirty-one invasive breast cancers were identified in the cohort during follow-up through 1998. Analyses within cohort showed no overall increased breast cancer risk after use of gonadotrophins, clomiphene, human chorionic gonadotrophin, or gonadotrophin-releasing hormone, whereas use of progesterone increased breast cancer risk (RR, 3.36; 95% confidence interval, 1.3-8.6). For all groups of fertility drugs, no relationships with number of cycles of use or years since first use of fertility drug were found. However, gonadotrophins may have a stronger effect on breast cancer risk among nulliparous women (RR, 1.69; 95% confidence interval, 1.03-2.77). Similar risk patterns were present for ductal, lobular, and tumors of other histologies, indicating identical etiologies.

CONCLUSION

The results showed no strong association between breast cancer risk and use of fertility drugs. Follow-up is, however, needed to assess long-term breast cancer risk after use of progesterone and among nulliparous women exposed to gonadotrophins.

Fertility Drugs and Gynecologic Cancer

Fertility drugs (FD) are spreading worldwide fast and therefore many studies have reviewed the possible association between the use of these drugs and cancer. Since the drugs used for ovulation induction during in vitro fertilization (IVF) like hCG, hMG, rFSH increase the levels of gonadal hormones, concerns have grown regarding the risk of developing cancer in breast, ovary, endometrium, and other target organs. In this review, we discuss a number of different studies published in recent years that show no association between the use of these drugs and most cancers.

Gonadotropins and ovarian carcinogenesis: a new era of basic research and its clinical implications

The possible relationship between gonadotropins and ovarian carcinoma development has received much attention, and in recent years, great progress has been made in basic and epidemiologic research about this issue. Gonadotropins sensitivity in the ovarian surface epithelium (OSE) and in a subset of ovarian carcinomas has been established in vivo and in vitro. Gonadotropins have been shown to induce various biologic actions in the OSE and ovarian carcinoma cells, such as changes in cell proliferation, apoptosis, cell adhesion, and chemosensitivity. These basic studies strongly suggest that gonadotropins are involved in the development and progression of ovarian carcinoma. In contrast, although earlier studies showed a significant risk of infertility therapy for ovarian carcinoma development, subsequent studies reported only slightly increased or no significant increased risk of gonadotropin stimulation and/or assisted reproductive technologies for ovarian carcinoma development. Therefore, the association between ovarian stimulation and ovarian carcinoma remains controversial. Nevertheless, since development of ovarian carcinoma in infertile women during infertility treatment is a serious concern for gynecologists, this review also covers important points for clinical practice, especially the issue of early detection of ovarian carcinoma.

Infertility, ovulation induction treatments and the incidence of breast cancer--a historical prospective cohort of Israeli women

CONTEXT

Ovulation induction drugs may be associated with increased breast cancer risk. Results so far have been inconclusive.

OBJECTIVE

To evaluate the association between infertility, exposure to ovulation induction drugs and the incidence of breast cancer.

DESIGN

Historical prospective cohort and nested case-control study.

SETTING

Institutional practice

PATIENTS

About 5,788 women attending five infertility centers in Israel between 1964 and 1984.

INTENTION

Abstracting of medical records and telephone interviews.

MAIN OUTCOME MEASURE

Breast cancer incidence was determined through linkage with the National Cancer Registry database. Standardized incidence ratios (SIRs) and 95% confidence intervals were computed by comparing the observed to the expected cancer rates in the general population. In addition, a nested case-control study within the cohort was performed with interviews of breast cancer cases and two matched controls.

RESULTS

The study cohort included 120,895 women years of follow-up. Compared to 115.2 expected breast cancer cases, 131 cases were observed (SIR = 1.1; 95% CI 0.9-1.4). Risk for breast cancer was significantly higher for women treated with clomiphene citrate (SIR = 1.4; 95% CI 1.0-1.8). Similar results were noted when comparisons were carried out between treated and untreated women, and when multivariate models were applied. In the nested case-control study, higher cycle index (OR = 2.2; 95% CI 1.0-4.8) and treatment with clomiphene citrate (OR=2.7; 95% CI 1.3-5.7) were associated with higher risk for breast cancer.

CONCLUSION

Infertility and usage of infertility drugs in general are not associated with increased risk for breast cancer. However, for infertile women treated with clomiphene citrate, breast cancer risk is elevated.

Reduced cancer incidence among patients with schizophrenia

BACKGROUND

The incidence of cancer in patients with schizophrenia has been conversely reported to be higher, lower, or similar to that in the general population. The effects of lifestyle factors such as excess smoking, exposure to neuroleptic medications, and genetic factors that may influence the incidence of cancer in this group are not clear. The current study was performed to evaluate the frequency of cancer in a large cohort of patients with schizophrenia and to determine the standardized incidence ratios (SIRs) of any malignancy in this group.

METHODS

Data regarding the design, setting, and participants of the current study were analyzed from a cohort of 3226 patients with schizophrenia who were enrolled in the computerized health registry of the Abarbanel Mental Health Center between 1993-2003. The mean age of the patients at the time of the diagnosis of cancer was 49 +/- 14.7 years, with the majority of patients (61%) being male. All patients with schizophrenia records in the database were combined with the records of the Israeli National Cancer Registry to identify pathologically confirmed cancer comorbidity. The cancer incidence rates among patients with schizophrenia were compared with the expected incidence in an age-matched and gender-matched general population sample for the same time interval.

RESULTS

Among 1247 female patients with schizophrenia, 22 (1.8%) developed breast cancer and 68 (5.5%) developed cancers of any type. Fifty-two of the 1979 male schizophrenic patients (2.6%) developed cancer. The SIRs were 0.58 (95% confidence interval [95% CI], 0.48-0.69) with a P value of < 0.05 for all cancers in the cohort, and 0.60 (95% CI, 0.37-0.90) for female breast cancer.

CONCLUSIONS

The results of the current study demonstrate a reduced risk of cancer in patients with schizophrenia. The mechanisms responsible for the lower risk need be investigated further.

In vitro fertilisation in Sweden: obstetric characteristics, maternal morbidity and mortality

OBJECTIVE

To investigate obstetric characteristics, maternal morbidity and mortality among Swedish women giving birth after in vitro fertilisation (IVF) treatment.

DESIGN

Register study.

SETTING

Nationwide study in Sweden.

SAMPLE

All women known to have had IVF in Sweden 1982-2001.

METHODS

Using Swedish health registers, women who had given birth after IVF were identified from all Swedish IVF clinics and compared with all women who gave birth. Analysis was performed with the Mantel-Haenszel technique.

MAIN OUTCOME MEASURES

Diagnoses during pregnancy, at delivery and at re-admission within 60 days after delivery and risk of cancer.

RESULTS

IVF women had an increased risk of bleeding in early pregnancy [odds ratio (OR) = 4.59, 95% confidence interval (95% CI) 4.08-5.15] and of ovarian torsion during pregnancy (OR = 10.6, 5.69-10.7). They were also more likely to encounter pre-eclampsia (OR = 1.63, 1.53-1.74), placental abruption (2.17, 1.74-2.72), placenta praevia (3.65, 3.15-4.23), bleeding in association with vaginal delivery (1.40, 1.38-1.50) and premature rupture of membranes (PROM) (2.54, 2.34-2.76). Interventions including caesarean sections (1.38, 1.32-1.43) and induction of labour (1.37, 1.29-1.46) in singleton pregnancies was more frequent. The type of IVF method had little effect on these results, but there was a tendency for women who had received intra-cytoplasmatic sperm injection (ICSI) to have slightly fewer complications than women having standard IVF. There was a significant decrease in cancer risk after IVF (0.79, 0.69-0.91) but a suggested increase in the risk of ovarian cancer both before (2.70, 1.49-4.91) and after (2.08, 1.15-3.76) IVF. No change in mortality was observed.

CONCLUSIONS

Women treated with IVF had an increased obstetric morbidity. This seems to contribute little to the well-known increased risk of preterm delivery.