Fertility drugs and cancer: a guideline

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

The 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.

Effects of Infertility Drug Exposure on the Risk of Borderline Ovarian Tumors: A Systematic Review and Meta-Analysis

Whether infertility drug exposure increases the risk of borderline ovarian tumors (BOTs) remains controversial. The present study was conducted with a comprehensive search for studies published from January 1990 to December 2021 in the online databases Cochrane Library, PubMed, Web of Science and EMBASE. We considered the first diagnosis of a BOT as the primary outcome. The odds ratio (OR) was calculated with corresponding 95% confidence intervals (CIs) for the risk of BOTs in patients who were treated with infertility drugs. Ten studies, a total of 2,779,511 women, qualified for inclusion in this meta-analysis. The pooled OR of 1.56 (95% CI: 1.09-2.22) revealed a significant positive association between infertility drugs and an increased risk for BOTs, but for specific drugs, only CC plus Gn had statistical significance. No publication bias was detected using the Egger and Begg tests (p > 0.05). A significant difference in BOT incidence was observed among infertile women and nulliparous women who were treated with or without infertility drugs. In conclusion, the use of infertility drugs may increase the risk of BOTs, but a dose-dependent relationship was not observed between the number of assisted reproduction technology cycles and the risk of BOTs, and infertile women who successfully became pregnant might have a reduced risk. Registration: PROSPERO, CRD42022330775.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The continuing evolution of birth cohort studies: achievements and challenges

Well-designed birth cohorts are able to estimate prevalence/distribution of various health events/outcomes, and to link early-life origins with adult health and function. The past two decades have seen a surge in the establishment of new birth cohorts and their accompanying research. We discussed distinct designs of current birth cohort studies, reviewed their achievements, and highlighted insights obtained from birth cohort studies, as well as challenges we are facing. Birth cohort studies are providing increasing opportunities to identify determining factors for short- and long-term health, yielding substantial evidence to uncover biological mechanisms of diseases and phenotypes, and providing further insights for public health. Dynamic monitoring, accurate measurements, long-term follow-ups and collaborative efforts are warranted in new birth cohorts to elucidate the nature of life course relationships in contemporary generation.

Healthcare Use in the Five Years Before a First Infertility Diagnosis: A Danish Register-Based Case–Control Study in the CROSS-TRACKS Cohort

Purpose

Infertility may affect somatic and mental health later in life. Nevertheless, health status before diagnosed infertility is sparsely studied in women. We aimed to describe healthcare use in primary and secondary care before a first infertility diagnosis and compare use between cases and controls.

Materials and Methods

The case–control study was based on register data and used incidence density sampling. From the CROSS-TRACKS Cohort, we included women residing in the Horsens area in Denmark in 2012–2018 (n = 54,175). Eligible women were aged 18–40 years, nulliparous, and living in heterosexual relationships. Cases were women with a first infertility diagnosis in the Danish National Patient Registry (index date). Five controls were matched on age, birth year, and calendar time. Through linkage to Danish national health registries, we identified general practitioner (GP) attendance, paraclinical examinations, hospital contacts, diagnoses, and redeemed prescriptions. Healthcare use from one year to five years before index date was compared with conditional logistic regression.

Results

We identified 711 cases and 3555 controls. At one year before index date, cases consulted their GP (odds ratio (OR) = 5.2, 95% confidence interval (CI): 3.2, 8.3) and visited hospital (OR = 1.2, 95% CI: 1.0, 1.4) and redeemed prescriptions (OR = 2.3 95% CI: 1.9, 2.7) more often compared to controls. Cases more often had blood and hemoglobin tests performed, redeemed more drugs related to genitourinary and hormonal diseases, and were more often diagnosed with endocrine and genitourinary diseases in the year before a first infertility diagnosis compared to controls. Cases and controls had comparable healthcare use from five years to one year before a first infertility diagnosis.

Conclusion

Cases and controls had similar healthcare use from five years to one year before a first infertility diagnosis. However, cases had a higher healthcare use in the year preceding a first infertility diagnosis compared to controls.

RUBIC (ReproUnion Biobank and Infertility Cohort): A binational clinical foundation to study risk factors, life course, and treatment of infertility and infertility-related morbidity

BACKGROUND

Infertility affects 15%-25% of all couples during their reproductive life span. It is a significant societal and public health problem with potential psychological, social, and economic consequences. Furthermore, infertility has been linked to adverse long-term health outcomes. Despite the advanced diagnostic and therapeutic techniques available, approximately 30% of infertile couples do not obtain a live birth after fertility treatment. For these couples, there are no further options to increase their chances of a successful pregnancy and live birth.

OBJECTIVES

Three overall questions will be studied: (1) What are the risk factors and natural life courses of infertility, early embryonic loss, and adverse pregnancy outcomes? (2) Can we develop new diagnostic and prognostic biomarkers for fecundity and treatment success? And (3) what are the health characteristics of women and men in infertile couples at the time of fertility treatment and during long-term follow-up?

MATERIAL AND METHODS

ReproUnion Biobank and Infertility Cohort (RUBIC) is established as an add-on to the routine fertility management at Copenhagen University Hospital Departments in the Capital Region of Denmark and Reproductive Medicine Centre at Skåne University Hospital in Sweden. The aim is to include a total of 5000 couples equally distributed between Denmark and Sweden. The first patients were enrolled in June 2020. All eligible infertile couples are prospectively asked to participate in the project. Participants complete an extensive questionnaire and undergo a physical examination and collection of biospecimens (blood, urine, hair, saliva, rectal swabs, feces, semen, endometrial biopsies, and vaginal swabs). After the cohort is established, the couples will be linked to the Danish and Swedish national registers to obtain information on parental, perinatal, childhood, and adult life histories, including disease and medication history. This will enable us to understand the causes of infertility and identify novel therapeutic options for this important societal problem.

Safety of in-vitro fertilization in women with endometriosis

Management of women with endometriosis in general is complex. It requires a multidisciplinary and tailored approach. The time of in-vitro fertilization (IVF) may be particularly complicated because women with the disease face peculiar additional risks. In particular, oocytes retrieval may be more difficult and women with endometriomas are exposed to a low but consistent risk of infection and ovarian abscess development. There are also concerns regarding progression of deep invasive peritoneal lesions and misdiagnosis of an occult early ovarian cancer. However, evidence on these latter points is more controversial. Taken together, this body evidence is generally reassuring and does not justify prophylactic surgery prior to IVF to shrink these risks. However, given the uncertainties, women with endometriosis must be informed in depth of these peculiar additional risks.

The Danish National Register of assisted reproductive technology: content and research potentials

The Danish National Register of assisted reproductive technology (ART) was initially established in 1994. The register comprises complete information on all ART procedures in public and private clinics in Denmark from 2013 and onwards, including baseline information on the cause of infertility and a number of health-related patient characteristics. The register enables monitoring and research on infertility treatment and reproductive topics in single women or couples seeking assisted reproduction, and the register is thus a key component of the Danish health information system within human reproduction. We aimed to provide an updated description of the register including advantages and pitfalls when using the register for reproductive epidemiological research, and a description of the accessibility for researchers. The Danish ART register is a valuable tool for epidemiological research. However, the inherent strengths and limitations ought to be in perspective when designing studies and interpreting the study results. Reports with annually aggregated data on ART treatments, can be accessed on the Danish Health Data Authority web page and researchers may obtain access to individual pseudonomized data via secure servers at the Danish Health Data Authority and Statistics Denmark.

Endometriosis and cancer: a systematic review and meta-analysis

BACKGROUND

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

OBJECTIVE AND RATIONALE

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

SEARCH METHODS

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

OUTCOMES

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

WIDER IMPLICATIONS

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

Long-Term Risk of Ovarian Cancer and Borderline Tumors After Assisted Reproductive Technology

BACKGROUND

Long-term effects of assisted reproductive technology (ART) on ovarian tumor risk are unknown.

METHODS

This nationwide cohort study comprises 30 625 women who received ovarian stimulation for ART in 1983-2000 and 9988 subfertile women not treated with ART. Incident invasive and borderline ovarian tumors were ascertained through linkage with the Netherlands Cancer Registry and the Dutch Pathology Registry until July 2018. Ovarian tumor risk in ART-treated women was compared with risks in the general population and the subfertile non-ART group. Statistical tests were 2-sided.

RESULTS

After a median follow-up of 24 years, 158 invasive and 100 borderline ovarian tumors were observed. Ovarian cancer risk in the ART group was increased compared with the general population (standardized incidence ratio [SIR] = 1.43, 95% confidence interval [CI] = 1.18 to 1.71) but not when compared with the non-ART group (age- and parity-adjusted hazard ratio [HR] = 1.02, 95% CI = 0.70 to 1.50). Risk decreased with higher parity and with a larger number of successful ART cycles (resulting in childbirth, Ptrend = .001) but was not associated with the number of unsuccessful ART cycles. Borderline ovarian tumor risk was increased in ART-treated women compared with the general population (SIR = 2.20, 95% CI = 1.66 to 2.86) and with non-ART women (HR = 1.84, 95% CI = 1.08 to 3.14). Risk did not increase with more ART cycles or longer follow-up time.

CONCLUSIONS

Increased ovarian cancer risk in ART-treated women compared with the general population is likely explained by nulliparity rather than ART treatment. The increased risk of borderline ovarian tumors after ART must be interpreted with caution because no dose-response relationship was observed.

Subsequent Development of Epithelial Ovarian Cancer After Ovarian Surgery for Benign Ovarian Tumor: A Population-Based Cohort Study

Purpose

The goal of the current study is to determine the risk of subsequent development of epithelial ovarian cancer (EOC) in women after ovarian surgery for benign ovarian tumors.

Patients and Methods

We conducted the nationwide population-based historic cohort study using the National Health Insurance Research Database (NHIRD) of Taiwan. Eleven thousand six hundred twenty women who underwent ovarian surgery for ovarian benign diseases were analyzed. The collected data included age, types of ovarian surgery, medical history by Charlson comorbidity index (CCI), infertility (yes/no), pelvic inflammatory disease (PID) (yes/no), tubal ligation (yes/no), total/subtotal hysterectomy (TH/STH) (yes/no), and endometrioma (yes/no). We used the Kaplan-Meier method and the Log-rank test to evaluate the risk factors. Cox proportional hazard methods were used to evaluate risk factors for the subsequent development of EOC. Multivariate analysis using Cox stepwise forward regression was conducted for the covariate selected in univariate analysis. Hazard ratio (HR) and 95% confidence interval (CI) were calculated using the Wald test.

Results

Subsequent EOC incidence rate (IR, incidence per 10,000 person-years) of women after ovarian surgery for benign ovarian tumors was 2.98. Separating into four groups based on different age, IR of EOC was 1.57 (<30 years), 4.71 (30-39 years), 3.59 (40-49 years) and 0.94 (≥50 years), respectively. Univariate and multivariate analyses identified only high level of CCI (≥2 or more) as an independent risk factor for subsequent development of EOC in women after ovarian surgery for benign ovarian tumors (HR 59.17, 95% CI 7.50-466.80 in women with CCI level of 2 and HR 190.68, 95% CI 24.33-2494.19, in women with CCI level ≥3, respectively).

Conclusion

Our results, if confirmed, suggest that women with other comorbidities (CCI) should be well informed that they may have a higher risk of subsequent development of EOC when ovarian surgery is planned even though the final pathology showed a benign ovarian tumor.

Fertility-sparing treatment for early-stage epithelial ovarian cancer: Contemporary oncologic, reproductive and endocrinologic perspectives

AIM

Epithelial ovarian cancer (EOC) can be a devastating diagnosis in women of reproductive age who desire future fertility. However, in early-stage disease, fertility-sparing surgery (FSS) can be considered in appropriately selected patients.

METHODS

This is a narrative descriptive review of the recent literature on FSS for EOC from oncologic, reproductive and endocrinologic perspectives.

RESULTS

The recurrence rate following FSS performed for stage I EOC in published retrospective studies collectively is 13% but ranges from 5 to 29%, while mortality ranges from 0 to 18%. Five-year disease-free survival following FSS is over 90% but decreases with higher stage and grade. Recurrences following FSS are more likely to be localized with a more favorable prognosis compared to recurrences following radical surgery. Adjuvant chemotherapy is recommended in women with high-risk disease, and strategies to minimize gonadotoxicity during chemotherapy such as gonadotropin-releasing hormone (GnRH) agonists may be considered. Oocyte, embryo and/or ovarian cryopreservation can also be offered to patients desiring future biologic children. Reproductive outcomes following FSS, including pregnancy and miscarriage rates, resemble those of the general population, with a chance of successful pregnancy of nearly 80%.

CONCLUSION

In retrospective data, FSS appears to be oncologically safe in stage IA and IC grade 1-2 non-clear cell EOC. In patients with grade 3 tumors or clear cell histology, treatment can be individualized, weighing a slightly higher risk of recurrence with fertility goals. A multidisciplinary approach with oncology and reproductive endocrinology may be of utility to help these patients achieve their fertility goals.