Melanoma, thyroid, cervical, and colon cancer risk after use of fertility drugs

An umbrella review of meta-analyses regarding the incidence of female-specific malignancies after fertility treatment

IMPORTANCE

Understanding the potential risks associated with fertility treatments (FTs) can guide clinical decision and patient counseling.

OBJECTIVE

To investigate the validity of the association between the development of female-specific malignancies including ovarian, endometrial, breast, and cervical cancer after FT.

DATA SOURCES

A search of systematic reviews and meta-analyses was performed from inception to April 2022 within several databases: Cochrane Database of Systematic Reviews, EMBASE, Google Scholar, and PubMed.

STUDY SELECTION AND SYNTHESIS

The inclusion criteria required the incidence of each cancer subgroup to be stated in both the defined treatment group (controlled ovarian stimulation and/or in vitro fertilization [IVF] or intracytoplasmic sperm injection) and the control group (no-FT, general population). From 3,129 identified publications, 11 meta-analytical reviews consisting of 188 studies were selected for synthesis.

MAIN OUTCOME

The primary outcome of interest was incidence of each subgroup of cancer in the "FT" group compared with the "no-FT" group.

RESULTS

A statistically significant increase in incidence of ovarian (1,229/430,611 in FT group vs. 27,358/4,263,300 in no-FT group) cancer (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.00-1.45) and borderline ovarian tumors (117/414,729 in FT group vs. 934/2,626,324 in no-FT group) (OR, 1.87; 95% CI, 1.18-2.97) was observed. The incidence of ovarian cancer was higher with FT and IVF specifically (OR, 1.65; 95% CI, 1.07-2.54). For borderline ovarian tumors, the incidence was higher, not only with FT overall and IVF, but also according to the fertility drug regimen applied: clomiphene citrate (CC) only (OR, 1.99; 95% CI, 1.02-3.87), human menopausal gonadotropin only (OR, 3.46; 95% CI, 1.39-8.59), and CC and human menopausal gonadotropin combined (OR, 3.79; 95% CI, 1.47-9.77). When using the threshold for statistical significance, the meta-analyses relevant to ovarian cancers remained statistically significant (random-effects method). However, none of the examined associations could claim either strong or highly suggestive evidence.

CONCLUSION AND RELEVANCE

An observed association between ovarian cancer (including borderline ovarian tumors) and FT has been demonstrated. The association between FT and female-specific malignancy remains a contentious topic because there have been contradictory outcomes among meta-analyses. This umbrella review interrogates existing systematic reviews and meta-analyses on this topic and concludes that a statistically significant increase in the incidence of ovarian cancer and borderline ovarian tumors is associated with FT. These findings have a significant clinical impact because it helps to inform and provide effective counseling for patients undergoing FT.

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.

History of Infertility and Risk of Colorectal Cancer

BACKGROUND

There has been limited prior research on the association between infertility and risk of colorectal cancer.

METHODS

Data from postmenopausal women in the Women's Health Initiative were used to estimate the association between self-reported infertility (12 months of trying to get pregnant without achieving a pregnancy) and the risk of colorectal cancer using Cox proportional hazard models.

RESULTS

No association was observed between infertility and risk of postmenopausal colorectal cancer [RR, 0.97; 95% confidence interval (CI), 0.87-1.08], invasive colorectal cancer (RR, 0.99; 95% CI, 0.88-1.10), or colorectal cancer mortality (RR, 0.89; 95% CI, 0.71-1.12).

CONCLUSIONS

Infertility was not found to be associated with colorectal cancer risk among postmenopausal women. Risk did not vary by specific infertility diagnoses.

IMPACT

Infertility may not be associated with colorectal cancer risk.

A Narrative Review of the Role of Estrogen (Receptors) in Melanoma

In this narrative review, we attempt to provide an overview of the evidence regarding the role of estrogen (receptors) in cutaneous melanoma (CM). We reviewed 68 studies and 4 systematic reviews and meta-analyses published from 2002 up to and including 2022. The prevailing presence of estrogen receptor β (ERβ) instead of estrogen receptor α (ERα) in CM is notable, with ERβ potentially playing a protective role and being less frequently detected in progressive cases. While men with CM generally experience a less favorable prognosis, this distinction may become negligible with advancing age. The role of oral contraceptives (OC) and hormone replacement therapy (HRT) in CM remains controversial. However, recent studies tend to associate the use of these exogenous hormones with a heightened risk of CM, mostly only when using estrogen therapy and not in combination with progesterone. On the contrary, the majority of studies find no substantial influence of in vitro fertilization (IVF) treatment on CM risk. Reproductive factors, including younger age at first childbirth, higher parity, and shorter reproductive life, show conflicting evidence, with some studies suggesting a lower CM risk. We suggest an important role for estrogens in CM. More research is needed, but the integration of estrogens and targeting the estrogen receptors in melanoma therapy holds promise for future developments in the field.

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.

The risk of breast cancer and gynecologic malignancies after ovarian stimulation: Meta-analysis of cohort study

The effects of ovarian stimulation on breast and gynecological tumor incidence remain controversial. Therefore, the aim of this meta-analysis was to study the risk of cancer in ovarian stimulation. Of the 22713 studies initially identified, 28 were eligible for inclusion. The results revealed that the impact of ovarian cancer (RR = 1.33, [1.05; 1.69]) and cervical cancer (RR = 0.67, [0.46; 0.97]) is significant among the overall effects. In subgroup analysis, in the nulliparous population (RR = 0.81 [0.68; 0.96]) was the protective factor for the breast cancer. In the Caucasians subgroup (RR = 1.45, [1.12; 1.88]), the ovarian cancer incidence was statistically significant. In the Asian subgroup (RR = 1.51, [1.00; 2.28]), the endometrial cancer incidence was statistically significant. In the subgroup of Asians (RR = 0.55 [0.44; 0.68]) and the multiparous population (RR = 0.31, [0.21; 0.46]), them can be the statistically protective factor for the cervical cancer.

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.

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.

Thyroid nodules and thyroid cancer in women with positive thyroid screening in pregnancy: a double-centric, retrospective, cohort study

OBJECTIVE

Thyroid nodules are a common finding in the general population. The primary aim of the study was to determine the prevalence of thyroid nodules and cancer found by ultrasound (US) in women who underwent screening for thyroid dysfunction during pregnancy.

DESIGN

A double-centric, retrospective, cohort study.

PATIENTS AND METHODS

We searched through medical records, including thyroid ultrasonography, of pregnant women who were positively screened for thyroid disorders (using thyroid-stimulating hormone and thyroid antibodies) from an unselected population ('universal screening group', n = 690) and of women who underwent the testing based on the presence of clinical risk factors defined by American Thyroid Association ('case-finding group', n = 249).

RESULTS

Prevalence of benign and malignant thyroid nodules was lower in the 'universal screening group' than in the 'case-finding group' (9.9% vs 17.7%, P= 0.002, and 0.9% vs 7.2%, P< 0.001, respectively). Consistently, the thyroid cancer rate was lower among the nodules in the 'universal screening group' than in the 'case-finding group' (8.1% vs 29.0%, P= 0.003). Ultrasound EU-TIRADS (European Thyroid Imaging and Reporting Data System) category ≥4 had a 95.8% sensitivity for thyroid cancer. In palpable nodules, the prevalence of cancer was significantly higher than in the non-palpable ones (44.0% vs 2.2%, P < 0.001). In a multivariate regression analysis, thyroid nodules were associated with a history of infertility and parity.

CONCLUSIONS

Compared to the data from cancer registries, universal screening allowed detecting thyroid cancer in pregnancy three to five times more frequently, but the cancer rate among nodules (8.1%) did not differ from the common population. US had very good sensitivity for thyroid cancer in pregnancy.

Hormone therapy and melanoma in women

•

Melanocytes are known to respond to estrogen stimulation.

•

Knowledge of estrogen therapy in melanoma tumor behavior is essential to inform accurate patient prognostication.

•

There is limited evidence to suggest oral contraception and fertility treatments affect melanoma incidence.

•

The effect of menopausal hormone therapy on melanoma risk requires further investigation with multinational studies.

Although primary cutaneous melanoma accounts for approximately 3% of all malignant skin tumors, it has the greatest contribution to skin cancer–related death. Sex-specific differences in melanoma tumor behavior have been described, and melanoma pathogenesis may be hormonally mediated. This review aims to summarize the literature to date regarding the effects of hormone therapy on melanoma in women. Women's exogenous hormone use has changed dramatically over the past few decades. Thus, we focus on studies investigating the associations between oral contraception, fertility treatments, menopausal hormone therapy (MHT), and melanoma. Across hormone therapy types, there does not appear to be a well-established association between exogenous female hormones and melanoma incidence. However, MHT practices and formulations vary significantly across countries. Although MHT does not appear to increase melanoma risk in studies from the United States, conflicting results have been observed in Europe. Unopposed estrogen MHT formulations require further investigation to determine a clear pattern between hormone use and the development of melanoma.

Fertility drugs and incidence of thyroid cancer in a Danish nationwide cohort of 146 024 infertile women

STUDY QUESTION

Do fertility drugs increase the risk of thyroid cancer among infertile women?

SUMMARY ANSWER

The use of most types of fertility drugs was not associated with an increased risk of thyroid cancer.

WHAT IS KNOWN ALREADY

The incidence of thyroid cancer is higher for women than men, especially during reproductive years, indicating that reproductive hormones may be involved in the development of thyroid cancer. Only a few previous studies have examined the association between the use of fertility drugs and incidence of thyroid cancer and the results are inconclusive.

STUDY DESIGN, SIZE, DURATION

A retrospective, population-based cohort study including all 146 024 infertile women aged 20-45 years and living in Denmark in the period 1995-2017. The women were followed from the date of entry in the cohort (i.e. date of first infertility diagnosis) until the occurrence of thyroid cancer or any other cancer (except non-melanoma skin cancer), death, emigration, total thyroidectomy or the end of follow-up (31 December 2018), whichever occurred first. The median length of follow-up was 11.3 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 167 women were diagnosed with thyroid cancer during the follow-up period. Information on the use of specific fertility drugs (clomiphene citrate, gonadotropins, hCGs, GnRH receptor modulators and progesterone), thyroid cancer, covariates and vital status was obtained from the Danish Infertility Cohort and various Danish national registers. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% CIs for thyroid cancer overall and for papillary thyroid cancer.

MAIN RESULTS AND THE ROLE OF CHANCE

After adjustment for the calendar year of infertility diagnosis, the highest obtained level of education, parity status, obesity or thyroid disease and mutual adjustment for other registered fertility drugs, no marked associations were observed between the use of clomiphene citrate, hCG, gonadotropins or GnRH receptor modulators and risk of overall or papillary thyroid cancer. However, ever use of progesterone was associated with an increased rate of both overall (HR 1.63; 95% CI 1.07-2.48) and papillary (HR 1.66, 95% CI 1.04-2.65) thyroid cancer after mutual adjustment for other specific fertility drugs. For most specific fertility drugs, we observed a tendency toward higher associations with thyroid cancer within the first 5 years after the start of drug use than after 5 years from the start of use. No marked associations were detected according to the cumulative dose for any of the specific fertility drugs.

LIMITATIONS, REASONS FOR CAUTION

Despite a large study population, the statistical precision in some subgroup analyses may be affected due to the low number of thyroid cancer cases. Although we were able to adjust for a number of potential confounders, residual and unmeasured confounding may potentially have affected the observed associations, as we could not adjust for some factors that may influence the association between fertility drugs and thyroid cancer, including age at menarche and BMI.

WIDER IMPLICATIONS OF THE FINDINGS

Although this study, which is the largest to date, provides reassuring evidence that there is no strong link between the use of fertility drugs and thyroid cancer incidence, we observed a modest increased thyroid cancer incidence after the use of progesterone. However, we cannot rule out that this is a chance finding and the potential association between the use of progesterone and thyroid cancer should therefore be investigated further in large epidemiological studies. The results of the present study provide valuable knowledge for clinicians and other health care personnel involved in the diagnosis and treatment of infertility.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by research grants from the Jascha Foundation and the Aase and Ejner Danielsens Foundation. B.N. received honoraria and/or non-financial support by Gedeon Richter Nordics AB, IBSA Nordic APS and Merck KGAA. The remaining authors have no competing interests.

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.

A Potential Pathogenic Link Between Cancer of Female Reproductive System and Infertile Women Treated With Assisted Reproduction Techniques

Prevention and treatment of infertility remains a priority for developed countries where a large proportion of women undergo in vitro fertilization (IVF) after ovarian stimulation. Latest data suggest that, in the USA alone, almost eight million women of fertile age will have sought medical advice for fertility problems by 2025. However, over the last years, attention has been increasingly focused, and questions have risen, on the long-term health effects in women who underwent assisted reproductive technologies (ARTs). Since the emergence of ART, reports highlight a possible connection of ovarian stimulation and several types of gynaecological cancer, including ovarian, endometrial and cervical types, but due to limited scientific evidence, such a speculation is still under investigation. The objective of this review is to summarize the latest data of ovarian hyperstimulation and IVF, associated with the risk of gynecological tract cancer development.

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.

Estrogen Receptors and Melanoma: A Review

In the last three decades cutaneous melanoma has been widely investigated as a steroid hormone-sensitive cancer. Following this hypothesis, many epidemiological studies have investigated the relationship between estrogens and melanoma. No evidence to date has supported this association due to the great complexity of genetic, external and environmental factors underlying the development of this cancer. Molecular mechanisms through which estrogen and their receptor exert a role in melanoma genesis are still under investigation with new studies increasingly focusing on the discovery of new molecular targets for therapeutic treatments.

Melanoma Following In Vitro Fertilization: Co-incident or Coincidence?

Melanoma may occur during or after natural or in vitro fertilization-associated pregnancy. A 43-year-old woman, who had received in vitro fertilization and developed a melanoma five months postpartum is described. Some studies have not shown in vitro fertilization to increase melanoma risk; however, several investigations have observed melanoma risk to be greater in women who have had this treatment. Therefore, although a potential increased risk for melanoma has been observed in infertile women who were either pregnant before or following in vitro fertilization, whether in vitro fertilization is an etiologic risk factor in the pathogenesis of melanoma for these individuals-or is merely a coincidental event-remains to be established.

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.

Fertility Drugs Associated with Thyroid Cancer Risk: A Systematic Review and Meta-Analysis

Associations have been demonstrated between fertility drugs and a variety of hormone-sensitive carcinomas. The purpose of this study was to determine the relationship between fertility drugs used in the treatment of female infertility and the risk of thyroid cancer. To investigate the clinical significance of fertility drugs used for the treatment of female infertility and the risk associated with thyroid cancer, we performed a literature search using PubMed, MEDLINE, the Cochrane Library, the Web of Science, and EBSCOHOST for comparative studies published any time prior to July 21, 2017. The studies included women who were treated for infertility with fertility drugs, such as clomiphene citrate, gonadotropins, or other unspecified fertility agents, which reported the incidence of thyroid cancer as the main outcome. Eight studies were included in the meta-analyses. Among women with infertility, there was a significant positive association between thyroid cancer risk and the use of fertility drugs (relative risk [RR] = 1.35; 95% confidence interval [CI] 1.12–1.64; P = 0.002). Additionally, among women with infertility, the use of clomiphene citrate was associated with an increased risk of thyroid cancer compared to women who did not use fertility drugs (RR = 1.45; 95% CI 1.12–1.88; P = 0.005). After pooling results, we found that the parity status of infertile women using fertility drugs was not associated with thyroid cancer risk (RR = 0.99; 95% CI 0.61–1.58, P = 0.95). In summary, clomiphene citrate (the most commonly used fertility drug) and other fertility drugs are associated with an increased risk of thyroid cancer.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Safety of clomiphene citrate: a literature review

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

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.

Female Reproductive Factors and Differentiated Thyroid Cancer

Differentiated thyroid cancer (DTC) is markedly more common in women than men, the highest female-to-male ratio being recorded during the reproductive period. This evidence has led to the suggestion that female hormonal and reproductive factors may account for the observed DTC gender disparity. This review focuses on current evidence on the risk of DTC in conjunction with major female reproductive factors, including the impact of pregnancy on DTC occurrence and progression/recurrence. Overall, studies exploring the link between the risk of DTC and menstrual and menopausal factors, oral contraceptives and/or hormone replacement therapy, showed these associations, if any, to be generally weak. Nonetheless, there is some evidence that higher levels of exposure to estrogens during reproductive years may confer an increased risk of DTC. As far as pregnancy is concerned, it is unclear whether a potential association between parity and risk of DTC actually exists, and whether it is enhanced in the short-term following delivery. A possible role for pregnancy-related factors in DTC progression has been recently suggested by some reports, the results of which are consistent with a worse outcome in the short-term of women diagnosed with DTC during gestation compared to non-pregnant control patients. Also, some progression of disease has been described in women with structural evidence of disease prior to pregnancy. However, there seems to be no impact from pregnancy in DTC-related death or overall survival. Several in vitro and animal studies have evaluated the influence of estrogens (E) and estrogen receptors (ERs) on thyroid cell proliferation. Presently available data are indicative of a role of E and ERs in thyroid cancer growth, although considerable discrepancies in respect to ER expression patterns in thyroid cancer tissues actually exist. Further studies providing more direct evidence on the possible role of E and of placental hormones and growth factors on thyroid growth may expand our knowledge on the mechanisms beyond the gender disparity of proliferative thyroid diseases.

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.

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

OBJECTIVE

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

DESIGN

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

SETTING

Reproductive endocrinology practices.

PATIENT(S)

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

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

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

RESULT(S)

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

CONCLUSION(S)

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

Cancer risk among parous women following assisted reproductive technology

STUDY QUESTION

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

SUMMARY ANSWER

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

WHAT IS KNOWN ALREADY

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

STUDY DESIGN, SIZE, DURATION

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

PARTICIPANTS/MATERIALS, SETTING, METHODS

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

MAIN RESULTS AND THE ROLE OF CHANCE

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

LIMITATIONS, REASONS FOR CAUTION

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

WIDER IMPLICATIONS OF THE FINDINGS

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

STUDY FUNDING/COMPETING INTEREST

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

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.

Melanoma risk after ovarian stimulation for in vitro fertilization

STUDY QUESTION

Do women treated with ovarian stimulation for IVF have an increased risk of melanoma?

SUMMARY ANSWER

Ovarian stimulation for IVF does not increase risk of melanoma, even after a prolonged follow-up.

WHAT IS KNOWN ALREADY

Although exposure to ultraviolet radiation is the major risk factor for melanoma, associations between female sex steroids and melanoma risk have also been suggested. The results of available studies on fertility drugs and melanoma risk are inconclusive since most studies had several methodological limitations such as short follow-up, a small number of cases and no subfertile comparison group.

STUDY DESIGN, SIZE, DURATION

In 1996, a nationwide historic cohort study (the OMEGA-cohort) was established to examine the risk of cancer after ovarian stimulation for IVF. After a median follow-up of 17 years, cancer incidence was ascertained through linkage with the Netherlands Cancer Registry. Melanoma risk in the cohort was compared with that in the general population and between the IVF group and non-IVF group using multivariable Cox regression analyses.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The cohort comprises 19 158 women who received IVF between 1983 and 1995 and a comparison group of 5950 women who underwent subfertility treatments other than IVF. Detailed IVF-treatment data were obtained from the medical records and complete information on parity and age at first birth was obtained through linkage with the Dutch Municipal Personal Records Database.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 93 melanoma cases were observed. The risk of melanoma was not elevated among IVF-treated women, neither when compared with the general population (standardized incidence ratio = 0.89; 95% confidence interval (CI): 0.69-1.12), nor when compared with the non-IVF group (adjusted hazard ratio (HR) = 1.27; 95% CI: 0.75-2.15). A higher number of IVF cycles was associated with apparent but statistically non-significant risk increases (5-6 cycles HR = 1.92; ≥7 cycles HR = 1.79). However, no significant trend emerged. In women with more follicle stimulating hormone/human menopausal gonadotrophin ampoules comparable non-significant risk increases were found. A longer follow-up did not increase melanoma risk. Nulliparous women did not have a significantly higher melanoma risk than parous women (HR = 1.22; 95% CI: 0.81-1.84). However, women who were 30 years of age or older at first birth had a significantly higher melanoma risk than women who were younger than 30 years at first birth (age: 30-34 years HR = 4.57; 95% CI: 2.07-10.08, >34 years HR = 2.98; 95% CI: 1.23-7.21).

LIMITATIONS, REASONS FOR CAUTION

Despite our large cohort, the number of melanoma cases was rather small, especially in our comparison group, which hampered subgroup analyses.

WIDER IMPLICATIONS OF THE FINDINGS

Our results are reassuring for women who underwent IVF or are contemplating to start IVF. Since our cohort study is one of the largest published so far, with long-term follow-up, a subfertile comparison group, and detailed IVF-treatment data, our results add important information to the available evidence.

STUDY FUNDING/COMPETING INTEREST

This study was supported by grants from the Dutch Cancer Society (NKI 2006-3631), the Health Research and Development Counsel (28-2540) and the Dutch Ministry of Health.

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.

Correlation between fertility drugs use and malignant melanoma incidence: the state of the art

The relationship between fertility, reproductive hormones, and risk of malignant melanoma has acquired much interest in recent years. Melanocytes are hormonally responsive cells, and some in vitro studies demonstrated that estrogen hormones stimulate the growth of melanocytes. Moreover, estrogen receptors have been identified in melanoma cells, as well as in melanocytic nevi and in normal skin. Some evidences suggest a possible link between fertility treatments and the increased risk of malignant melanoma. This article addresses this association through a scrupulous search of the literature published thus far. The aim of this review is to determine the incidence of malignant melanoma in women treated with fertility drugs and to examine if the exposure to fertility treatments really increases the risk of malignant melanoma. In particular, our analysis focused on the different types of drugs and different treatment schedules used. Finally, this study provides additional insights regarding the long-term relationships between fertility drugs and the risk of malignant melanoma.

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.

Streamlining cutaneous melanomas in young women of the Belgian Mosan region

Sporadic cutaneous melanoma (SCM) has shown a dramatic increase in incidence in Caucasian populations over the past few decades. A particular epidemiological increase was reported in women during their childbearing age. In the Belgian Mosan region, a progressive unremitting increase in SCM incidence was noticed in young women for the past 35 years. The vast majority of these SCMs were of the superficial type without any obvious relationship with a large number of melanocytic nevi or with signs of frequent and intense sunlight exposures as disclosed by the extent in the mosaic subclinical melanoderma. A series of investigations pointed to a possible relationship linking the development of some SCM to the women hormonal status including the effect of hormonal disruptors. These aspects remain, however, unsettled and controversial. It is possible to differentiate and clearly quantify the SCM shape, size, scalloped border, and variegated pigmentation using computerized morphometry as well as fractal and multifractal methods.

Fertility medications and the risk of cancer

Cancer is among the leading causes of death, and malignant diseases of the female genital tract are among the most common sites. Reproductive factors that are also associated with infertility have been identified as risk factors. Hormones are thought to play a role in the induction and promotion of some type of cancers. Hormonal preparations affect the endocrine milieu and, by acting on the reproductive organs themselves, could even have a direct effect on carcinogenesis. Numerous case-control and cohort studies have tried to determine whether fertility medication use increases cancer risk. Overall, the current data is reassuring but most research groups drew conclusions based on a small number of cases and after a relatively short follow-up. Proper counseling prior to fertility medication use is important and further studies on even larger patient groups with more cancer cases are needed to support widespread use of fertility medications.

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.

Hormonal and reproductive factors in relation to melanoma in women: current review and meta-analysis

A number of studies have focused on possible relationships between characteristics of female endocrine status and melanoma (CM) risk; however, the link between melanoma, oral contraceptive (OC) and hormonal replacement therapy (HRT) use, and reproductive factors remains controversial. A comprehensive, systematic bibliographic search of the medical literature was conducted to identify relevant studies. Random effects models were used to summarise results. Subgroup, meta-regression and sensitivity analyses have been carried out to explore sources of between-study variation and bias. We included thirty-six observational studies published in the last 30 years. Summarising a total of 5626 melanoma cases, we did not find any significant melanoma risk associated with OC and HRT use. Several reproductive factors were also investigated, summarising data on 16787 melanoma cases. We found a significantly increased melanoma risk for late age at first birth, and women with more than one child may be at a lower risk for melanoma; however, socio-economic confounders were found to play a significant role in explaining this association. This study confirmed no increased risk of CM with the use of oral contraceptives and hormone replacement therapy: exogenous female hormones do not contribute to an increased risk of CM. In contrast, significant associations of CM with parity and age at first pregnancy were observed in this meta-analysis finds and warrant further research.

Characteristics and survival associated with ovarian cancer diagnosed as first cancer and ovarian cancer diagnosed subsequent to a previous cancer

OBJECTIVE

To examine the risk of subsequent primary ovarian cancer among women diagnosed previously with cancer (subsequent cohort) and to compare demographic and tumor characteristics affecting overall survival of these women and women diagnosed with first primary ovarian cancer (index cohort).

METHODS

We identified the two cohorts of women using the 1973-2005 Surveillance, Epidemiology and End Results (SEER) result data. We calculated relative risk of subsequent primary ovarian cancer and estimated 5-year risks of dying (hazard-ratios) after diagnosis of the first or subsequent primary ovarian cancer in the two cohorts, respectively using Cox modeling.

RESULTS

Women diagnosed with index cancers of the corpus uteri, colon, cervix, and melanoma at age younger than 50 had increased risk of ovarian cancer within 5 years after diagnosis (p<0.05); young breast cancer survivors had continued risk beyond 20 years. In 5-year follow-up survival analysis, the factors associated with a better survival (p<0.05) were similar in both cohorts and included more recent diagnosis; localized or regional disease; age <50 years at diagnosis; and being white versus black. A lower risk of dying from mucinous, endometrioid, or non-epithelial tumors than from serous was seen after 15 months (p<0.01), or after 32 months from diagnosis of the index and subsequent cohorts, respectively.

CONCLUSIONS

Age, stage, and histology affect ovarian cancer survival. The increased risk of ovarian cancer over time, especially among breast and colon cancer survivors who are less than 50 years of age, suggests common etiologies and necessitates careful surveillance by health care providers and increased survivors awareness through educational efforts.

Cancer risk among infertile women with androgen excess or menstrual disorders (including polycystic ovary syndrome)

OBJECTIVE

To define relationships of androgen excesses to cancer risk.

DESIGN

Retrospective cohort study.

SETTING

Five large infertility practices.

PATIENT(S)

Among 12,193 women evaluated for infertility during 1965-1988 and traced for cancer incidence through 1999, 2,560 had androgen excess or menstrual disorders; among these, 412 met established criteria for polycystic ovary syndrome.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Cancer incidence. Derivation of standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for cancer risk comparisons with the general population and rate ratios (RRs) for comparisons with other infertility patients.

RESULT(S)

Androgen excess/menstrual disorder patients showed significant SIRs for breast (1.31; 95% CI, 1.05-1.62) and uterine (2.02; 95% CI, 1.13-3.34) cancers and melanoma (1.96; 95% CI, 1.12-3.18). Significant associations for breast and uterine cancers were restricted to primary infertility patients (respective SIRs of 1.53 and 3.48). After adjustment for other cancer predictors, the only excess risk was for uterine cancer among primary infertility patients. Compared with women with secondary infertility and no androgen excess/menstrual disorder, those with primary infertility and a disorder had an RR of 1.88 (95% CI, 0.82-4.32). Cancer risks among the women with polycystic ovary syndrome or androgen excess disorders appeared to be similar to those in the more comprehensive group.

CONCLUSION(S)

Previous findings linking androgen excess disorders to elevated uterine cancer risks might largely reflect underlying risk profiles.

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.

Cancer risk after exposure to treatments for ovulation induction

Uncertainty continues as to whether treatments for ovulation induction are associated with increased risk of cancer. The authors conducted a long-term population-based historical cohort study of parous women. A total of 15,030 women in the Jerusalem Perinatal Study who gave birth in 1974-1976 participated in a postpartum survey. Cancer incidence through 2004 was analyzed using Cox's proportional hazards models, controlling for age and other covariates. Women who used drugs to induce ovulation (n = 567) had increased risks of cancer at any site (multivariate hazard ratio (HR) = 1.36, 95% confidence interval (CI): 1.06, 1.74). An increased risk of uterine cancer was found among women treated with ovulation-inducing agents (HR = 3.39, 95% CI: 1.28, 8.97), specifically clomiphene (HR = 4.56, 95% CI: 1.56, 13.34). No association was noted between use of ovulation-inducing agents and ovarian cancer (age-adjusted HR = 0.61, 95% CI: 0.08, 4.42). Ovulation induction was associated with a borderline-significant increased risk of breast cancer (multivariate HR = 1.42, 95% CI: 0.99, 2.05). Increased risks were also observed for malignant melanoma and non-Hodgkin lymphoma. These associations appeared stronger among women who waited more than 1 year to conceive. Additional follow-up studies assessing these associations by drug type, dosage, and duration are needed.

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.

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.