Assisted Reproductive Technology and Risk of Childhood Cancers

Cancer risk and male Infertility: Unravelling predictive biomarkers and prognostic indicators

In recent years, there has been a global increase in cases of male infertility. There are about 30 million cases of male infertility worldwide and male reproductive health is showing rapid decline in last few decades. It is now recognized as a potential risk factor for developing certain types of cancer, particularly genitourinary malignancies like testicular and prostate cancer. Male infertility is considered a potential indicator of overall health and an early biomarker for cancer. Cases of unexplained male factor infertility have high levels of oxidative stress and oxidative DNA damage and this induces both denovo germ line mutations and epimutations due to build up of 8-hydroxy 2 deoxygunaosine abase which is highly mutagenic and also induces hypomethylation and genomic instability. Consequently, there is growing evidence to explore the various factors contributing to an increased cancer risk. Currently, the available prognostic and predictive biomarkers associated with semen characteristics and cancer risk are limited but gaining significant attention in clinical research for the diagnosis and treatment of elevated cancer risk in the individual and in offspring. The male germ cell being transcriptionally and translationally inert has a highly truncated repair mechanism and has minimal antioxidants and thus most vulnerable to oxidative injury due to environmental factors and unhealthy lifestyle and social habits. Therefore, advancing our understanding requires a thorough evaluation of the pathophysiologic mechanisms at the DNA, RNA, protein, and metabolite levels to identify key biomarkers that may underlie the pathogenesis of male infertility and associated cancer. Advanced methodologies such as genomics, epigenetics, proteomics, transcriptomics, and metabolomics stand at the forefront of cutting-edge approaches for discovering novel biomarkers, spanning from infertility to associated cancer types. Henceforth, in this review, we aim to assess the role and potential of recently identified predictive and prognostic biomarkers, offering insights into the success of assisted reproductive technologies, causes of azoospermia and idiopathic infertility, the impact of integrated holistic approach and lifestyle modifications, and the monitoring of cancer susceptibility, initiation and progression. Comprehending these biomarkers is crucial for providing comprehensive counselling to infertile men and cancer patients, along with their families.

Preimplantation genetic testing in the current era, a review

BACKGROUND

Preimplantation genetic testing (PGT), also referred to as preimplantation genetic diagnosis (PGD), is an advanced reproductive technology used during in vitro fertilization (IVF) cycles to identify genetic abnormalities in embryos prior to their implantation. PGT is used to screen embryos for chromosomal abnormalities, monogenic disorders, and structural rearrangements.

DEVELOPMENT OF PGT

Over the past few decades, PGT has undergone tremendous development, resulting in three primary forms: PGT-A, PGT-M, and PGT-SR. PGT-A is utilized for screening embryos for aneuploidies, PGT-M is used to detect disorders caused by a single gene, and PGT-SR is used to detect chromosomal abnormalities caused by structural rearrangements in the genome.

PURPOSE OF REVIEW

In this review, we thoroughly summarized and reviewed PGT and discussed its pros and cons down to the minutest aspects. Additionally, recent studies that highlight the advancements of PGT in the current era, including their future perspectives, were reviewed.

CONCLUSIONS

This comprehensive review aims to provide new insights into the understanding of techniques used in PGT, thereby contributing to the field of reproductive genetics.

Medically Assisted Reproduction and Risk of Cancer Among Offspring

Importance

Cancer is a leading cause of death among children worldwide. Treatments used for medically assisted reproduction (MAR) are suspected risk factors because of their potential for epigenetic disturbance and associated congenital malformations.

Objective

To assess the risk of cancer, overall and by cancer type, among children born after MAR compared with children conceived naturally.

Design, Setting, and Participants

For this cohort study, the French National Mother-Child Register (EPI-MERES) was searched for all live births that occurred in France between January 1, 2010, and December 31, 2021 (and followed up until June 30, 2022). The EPI-MERES was built from comprehensive data of the French National Health Data System. Data analysis was performed from December 1, 2021, to June 30, 2023.

Exposure

Use of assisted reproduction technologies (ART), such as fresh embryo transfer (ET) or frozen ET (FET), and artificial insemination (AI).

Main Outcomes and Measures

The risk of cancer was compared, overall and by cancer type, among children born after fresh ET, FET, or AI and children conceived naturally, using Cox proportional hazards regression models adjusted for maternal and child characteristics at birth.

Results

This study included 8 526 306 children with a mean (SD) age of 6.4 (3.4) years; 51.2% were boys, 96.4% were singletons, 12.1% were small for gestational age at birth, and 3.1% had a congenital malformation. There were 260 236 children (3.1%) born after MAR, including 133 965 (1.6%) after fresh ET, 66 165 (0.8%) after FET, and 60 106 (0.7%) after AI. A total of 9256 case patients with cancer were identified over a median follow-up of 6.7 (IQR, 3.7-9.6) years; 165, 57, and 70 were born after fresh ET, FET, and AI, respectively. The overall risk of cancer did not differ between children conceived naturally and those born after fresh ET (hazard ratio [HR], 1.12 [95% CI, 0.96 to 1.31]), FET (HR, 1.02 [95% CI, 0.78 to 1.32]), or AI (HR, 1.09 [95% CI, 0.86 to 1.38]). However, the risk of acute lymphoblastic leukemia was higher among children born after FET (20 case patients; HR 1.61 [95% CI, 1.04 to 2.50]; risk difference [RD], 23.2 [95% CI, 1.5 to 57.0] per million person-years) compared with children conceived naturally. Moreover, among children born between 2010 and 2015, the risk of leukemia was higher among children born after fresh ET (45 case patients; HR, 1.42 [95% CI, 1.06 to 1.92]; adjusted RD, 19.7 [95% CI, 2.8 to 43.2] per million person-years).

Conclusions and Relevance

The findings of this cohort study suggest that children born after FET or fresh ET had an increased risk of leukemia compared with children conceived naturally. This risk, although resulting in a limited number of cases, needs to be monitored in view of the continuous increase in the use of ART.

Risk factors for childhood brain tumours: A systematic review and meta-analysis of observational studies from 1976 to 2022

BACKGROUND

Childhood brain tumours (CBTs) are the leading cause of cancer death in children under the age of 20 years globally. Though the aetiology of CBT remains poorly understood, it is thought to be multifactorial. We aimed to synthesize potential risk factors for CBT to inform primary prevention.

METHODS

We conducted a systematic review and meta-analysis of epidemiological studies indexed in the PubMed, Web of Science, and Embase databases from the start of those resources through 27 July 2023. We included data from case-control or cohort studies that reported effect estimates for each risk factor around the time of conception, during pregnancy and/or during post-natal period. Random effects meta-analysis was used to estimate summary effect sizes (ES) and 95% confidence intervals (CIs). We also quantified heterogeneity (I2) across studies.

FINDINGS

A total of 4040 studies were identified, of which 181 studies (85 case-control and 96 cohort studies) met our criteria for inclusion. Of all eligible studies, 50% (n = 91) were conducted in Europe, 32% (n = 57) in North America, 9% (n = 16) in Australia, 8% (n = 15) in Asia, 1% (n = 2) in South America, and none in Africa. We found associations for some modifiable risk factors including childhood domestic exposures to insecticides (ES 1.44, 95% CI 1.20-1.73) and herbicides (ES 2.38, 95% CI 1.31-4.33). Maternal domestic exposure to insecticides (ES 1.45, 95% CI 1.09-1.94), maternal consumption of cured meat (ES 1.51, 95% CI 1.05-2.17) and coffee ≥ 2 cups/day (ES 1.45, 95% 95% CI 1.07-1.95) during pregnancy, and maternal exposure to benzene (ES 2.22; 95% CI 1.01-4.88) before conception were associated with CBTs in case-control studies. Also, paternal occupational exposure to pesticides (ES 1.48, 95% CI 1.23-1.77) and benzene (ES 1.74, 95% CI 1.10-2.76) before conception and during pregnancy were associated in case-control studies and in combined analysis. On the other hand, assisted reproductive technology (ART) (ES 1.32, 95% CI 1.05-1.67), caesarean section (CS) (ES 1.12, 95% CI 1.01-1.25), paternal occupational exposure to paint before conception (ES 1.56, 95% CI 1.02-2.40) and maternal smoking > 10 cigarettes per day during pregnancy (ES 1.18, 95% CI 1.00-1.40) were associated with CBT in cohort studies. Maternal intake of vitamins and folic acid during pregnancy was inversely associated in cohort studies. Hormonal/infertility treatment, breastfeeding, child day-care attendance, maternal exposure to electric heated waterbed, tea and alcohol consumption during pregnancy were among those not associated with CBT in both case-control and cohort studies.

CONCLUSION

Our results should be interpreted with caution, especially as most associations between risk factors and CBT were discordant between cohort and case-control studies. At present, it is premature for any CBT to define specific primary prevention guidelines.

Factors associated with postpartum depressive symptoms among women who conceived with infertility treatment

Infertility treatment experiences may accumulate and influence postpartum psychological well-being among women with infertility. However, the association between infertility treatment experiences and postpartum depressive symptoms remained unclear. This cross-sectional survey aimed to describe depressive symptom scores of 180 women, who conceived while undergoing infertility treatment, at 2-6 months after childbirth, and to explore factors, including infertility history and treatment experiences, associated with postpartum depressive symptoms. Data were collected via telephone interviews and patient record reviews. Postpartum depressive symptoms were measured using the Edinburgh Postnatal Depression Scale, with a cutoff score of 10. The prevalence of postpartum depressive symptoms was 34.4 %. Higher perceived stress levels after childbirth than before undergoing infertility treatment, a duration of infertility diagnosis longer than three years, maternal age >35 years, pregnancy conceived through in vitro fertilization (IVF), and experiencing all three lines of infertility treatment, namely ovarian stimulation, intrauterine insemination, and IVF, were associated with a higher risk of postpartum depressive symptoms. Breastfeeding, social support, and baby sex in line with stated preference were negatively associated with postpartum depressive symptoms. There were no significant interactions between the variables. The women's infertility history and treatment experiences were found to have influenced their postpartum depressive symptoms, especially among women who had a long duration of infertility, conceived through IVF, and had received all lines of infertility treatment.

Cancer risk in children, adolescents, and young adults conceived by ART in 1983-2011

STUDY QUESTION

Do children, adolescents, and young adults born after ART, including IVF, ICSI and frozen-thawed embryo transfer (FET), have an increased risk of cancer compared with children born to subfertile couples not conceived by ART and children from the general population?

SUMMARY ANSWER

After a median follow-up of 18 years, the overall cancer risk was not increased in children conceived by ART, but a slight risk increase was observed in children conceived after ICSI.

WHAT IS KNOWN ALREADY

There is growing evidence that ART procedures could perturb epigenetic processes during the pre-implantation period and influence long-term health. Recent studies showed (non-)significantly increased cancer risks after ICSI and FET, but not after IVF.

STUDY DESIGN SIZE DURATION

A nationwide historical cohort study with prospective follow-up was carried out, including all live-born offspring from women treated with ART between 1983 and 2011 and subfertile women not treated with ART in one of the 13 Dutch IVF clinics and two fertility centers.

PARTICIPANTS/MATERIALS SETTING METHODS

Children were identified through the mothers' records in the Personal Records Database. Information on the conception method of each child was collected through the mother's medical record. In total, the cohort comprises 89 249 live-born children of subfertile couples, of whom 51 417 were conceived using ART and 37 832 were not (i.e. conceived naturally, through ovulation induction, or after IUI). Cancer incidence was ascertained through linkage with the Netherlands Cancer Registry for the period 1989-2019. Cancer risk in children conceived using ART was compared with risk in children born to subfertile couples but not conceived by ART (hazard ratio (HR)) and children from the general population (standardized incidence ratios (SIRs)).

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 358 cancers were observed after a median follow-up of 18 years. Overall cancer risk was not increased in children conceived using ART, when compared with the general population (SIR = 0.96, 95% CI = 0.81-1.12) or with children from subfertile couples not conceived by ART (HR = 1.06, 95% CI = 0.84-1.33). Compared with children from subfertile couples not conceived by ART, the use of IVF or FET was not associated with increased cancer risk, but ICSI was associated with a slight risk increase (HR = 1.58, 95% CI = 1.08-2.31). Risk of cancer after ART did not increase at older ages (≥18 years, HR = 1.26, 95% CI = 0.88-1.81) compared to cancer risk in children not conceived by ART.

LIMITATIONS REASONS FOR CAUTION

The observed increased risk among children conceived using ICSI must be interpreted with caution owing to the small number of cases.

WIDER IMPLICATIONS OF THE FINDINGS

After a median follow-up of 18 years, children conceived using ART do not have an increased overall cancer risk. Many large studies with prolonged follow-up are needed to investigate cancer risk in (young) adults conceived by different types of ART. In addition, international pooling of studies is recommended to provide sufficient power to study risk of specific cancer sites after ART.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by The Dutch Cancer Society (NKI 2006-3631) that funded the OMEGA-women's cohort, Children Cancer Free (KIKA; 147) that funded the OMEGA-I-II offspring cohort. The OMEGA-III offspring cohort was supported by a Postdoc Stipend of Amsterdam Reproduction & Development, and the Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health under Award Number R01HD088393. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Infertility Treatments Resulting in Twin Pregnancy: Does It Increase the Risk for Future Childhood Malignancy

Background: Controversy exists in the literature regarding the possible association between infertility treatments in singleton pregnancies and long-term risk for childhood malignancy. Data regarding infertility treatments in twins and long-term childhood malignancies are scarce. Objective: We sought to investigate whether twins conceived following infertility treatments are at an increased risk for childhood malignancy. Study design: A population-based retrospective cohort study, comparing the risk for future childhood malignancy in twins conceived by infertility treatments (in vitro fertilization and ovulation induction) and those who were conceived spontaneously. Deliveries occurred between the years 1991 and 2021 in a tertiary medical center. A Kaplan-Meier survival curve was used to compare the cumulative incidence of childhood malignancies, and a Cox proportional hazards model was constructed to control for confounders. Results: During the study period, 11,986 twins met the inclusion criteria; 2910 (24.3%) were born following infertility treatments. No statistically significant differences were noted between the groups comparing the rate (per 1000) of childhood malignancies (2.0 in the infertility treatments group vs. 2.2 in the comparison group, OR 1.04, 95% CI 0.41-2.62; p = 0.93). Likewise, the cumulative incidence over time was comparable between the groups (log-rank test, p = 0.87). In a Cox regression model, controlling for maternal and gestational age, no significant differences in childhood malignancies were noted between the groups (adjusted HR = 0.82, 95% CI 0.49-1.39, p = 0.47). Conclusions: In our population, twins conceived following infertility treatments are not at an increased risk for childhood malignancies.