Inter-individual variation in ovarian reserve after gonadotoxic treatment in female childhood cancer survivors - a genome-wide association study: results from PanCareLIFE

OBJECTIVE

We aimed to discover new variants associated with low ovarian reserve after gonadotoxic treatment among adult female childhood cancer survivors using a genome-wide association study approach.

DESIGN

Genome-wide association study.

SUBJECTS

A discovery cohort of adult female childhood cancer survivors, from the pan-European PanCareLIFE cohort (n=743; median age: 25.8 years), excluding those who received bilateral ovarian irradiation, bilateral oophorectomy, central nerve system or total body irradiation, or stem cell transplantation. Replication was attempted in the USA-based St. Jude Lifetime Cohort (n=391; median age: 31.3 years).

EXPOSURE

Female childhood cancer survivors are at risk of therapy-related gonadal impairment. Alkylating agents are well-established risk factors, and the inter-individual variability in gonadotoxicity may be explained by genetic polymorphisms. Data were collected in real-life conditions and cyclophosphamide equivalent dose was used to quantify alkylation agent exposure.

INTERVENTION

No intervention was performed.

MAIN OUTCOME MEASURE

Anti-Müllerian hormone (AMH) levels served as a proxy for ovarian function and findings were combined in a meta-analysis.

RESULTS

Three genome-wide significant (<5.0x10-8) and 16 genome-wide suggestive (<5.0x10-6) loci were associated with log-transformed AMH levels, adjusted for cyclophosphamide equivalent dose of alkylating agents, age at diagnosis, and age at study in the PanCareLIFE cohort. Based on effect allele frequency (EAF) (>0.01 if not genome-wide significant), p-value (<5.0×10-6), and biological relevance, 15 SNPs were selected for replication. None of the SNPs were statistically significantly associated with AMH levels. A meta-analysis indicated that rs78861946 was associated at borderline genome-wide statistical significance (Reference/effect allele: C/T; EAF: 0.04, Beta (SE): -0.484 (0.091), p-value= 9.39×10-8).

CONCLUSION

This study found no genetic variants associated with a lower ovarian reserve after gonadotoxic treatment, as the findings of this GWAS were not statistically significant replicated in the replication cohort. Suggestive evidence for potential importance of one variant is briefly discussed, but the lack of statistical significance calls for larger cohort sizes. As the population of childhood cancer survivors is increasing, large-scale and systematic research is needed to identify genetic variants that could aid predictive risk models of gonadotoxicity and as well as fertility preservation options for childhood cancer survivors.

Oncofertility Perspectives for Girls with Cancer

Infertility is a serious early, as well as late, effect of childhood cancer treatment. If addressed in a timely manner at diagnosis, fertility preservation measures can be taken, preferably before the start of cancer treatment. However, pediatric oncologists might remain reluctant to offer counseling on fertility-preservation methods, although infrastructure to freeze ovarian tissue has become available and is currently considered standard care for pre- and postpubertal girls at high risk of gonadal damage. More importantly, risk factors have been identified for cancer treatment-related impairment of gonadal function, and the first successful pregnancies have been reported after autotransplanted ovarian tissue, which has been harvested from children. Additionally, great progress has been made in the field of ex vivo maturation of oocytes in frozen ovarian tissue, which provides opportunities for those at risk of ovarian micrometastasis. Hence, it is time to counsel girls at risk and make every effort to cryopreserve their ovarian tissue, now more than ever before.

Effect of Genetic Variation in CYP450 on Gonadal Impairment in a European Cohort of Female Childhood Cancer Survivors, Based on a Candidate Gene Approach: Results from the PanCareLIFE Study

BACKGROUND

Female childhood cancer survivors (CCSs) carry a risk of therapy-related gonadal dysfunction. Alkylating agents (AA) are well-established risk factors, yet inter-individual variability in ovarian function is observed. Polymorphisms in CYP450 enzymes may explain this variability in AA-induced ovarian damage. We aimed to evaluate associations between previously identified genetic polymorphisms in CYP450 enzymes and AA-related ovarian function among adult CCSs.

METHODS

Anti-Müllerian hormone (AMH) levels served as a proxy for ovarian function in a discovery cohort of adult female CCSs, from the pan-European PanCareLIFE cohort (n = 743; age (years): median 25.8, interquartile range (IQR) 22.1-30.6). Using two additive genetic models in linear and logistic regression, nine genetic variants in three CYP450 enzymes were analyzed in relation to cyclophosphamide equivalent dose (CED) score and their impact on AMH levels. The main model evaluated the effect of the variant on AMH and the interaction model evaluated the modifying effect of the variant on the impact of CED score on log-transformed AMH levels. Results were validated, and meta-analysis performed, using the USA-based St. Jude Lifetime Cohort (n = 391; age (years): median 31.3, IQR 26.6-37.4).

RESULTS

CYP3A4*3 was significantly associated with AMH levels in the discovery and replication cohort. Meta-analysis revealed a significant main deleterious effect (Beta (95% CI): -0.706 (-1.11--0.298), p-value = 7 × 10-4) of CYP3A4*3 (rs4986910) on log-transformed AMH levels. CYP2B6*2 (rs8192709) showed a significant protective interaction effect (Beta (95% CI): 0.527 (0.126-0.928), p-value = 0.01) on log-transformed AMH levels in CCSs receiving more than 8000 mg/m2 CED.

CONCLUSIONS

Female CCSs CYP3A4*3 carriers had significantly lower AMH levels, and CYP2B6*2 may have a protective effect on AMH levels. Identification of risk-contributing variants may improve individualized counselling regarding the treatment-related risk of infertility and fertility preservation options.

Possible modification of BRSK1 on the risk of alkylating chemotherapy-related reduced ovarian function

STUDY QUESTION

Do genetic variations in the DNA damage response pathway modify the adverse effect of alkylating agents on ovarian function in female childhood cancer survivors (CCS)?

SUMMARY ANSWER

Female CCS carrying a common BR serine/threonine kinase 1 (BRSK1) gene variant appear to be at 2.5-fold increased odds of reduced ovarian function after treatment with high doses of alkylating chemotherapy.

WHAT IS KNOWN ALREADY

Female CCS show large inter-individual variability in the impact of DNA-damaging alkylating chemotherapy, given as treatment of childhood cancer, on adult ovarian function. Genetic variants in DNA repair genes affecting ovarian function might explain this variability.

STUDY DESIGN, SIZE, DURATION

CCS for the discovery cohort were identified from the Dutch Childhood Oncology Group (DCOG) LATER VEVO-study, a multi-centre retrospective cohort study evaluating fertility, ovarian reserve and risk of premature menopause among adult female 5-year survivors of childhood cancer. Female 5-year CCS, diagnosed with cancer and treated with chemotherapy before the age of 25 years, and aged 18 years or older at time of study were enrolled in the current study. Results from the discovery Dutch DCOG-LATER VEVO cohort (n = 285) were validated in the pan-European PanCareLIFE (n = 465) and the USA-based St. Jude Lifetime Cohort (n = 391).

PARTICIPANTS/MATERIALS, SETTING, METHODS

To evaluate ovarian function, anti-Müllerian hormone (AMH) levels were assessed in both the discovery cohort and the replication cohorts. Using additive genetic models in linear and logistic regression, five genetic variants involved in DNA damage response were analysed in relation to cyclophosphamide equivalent dose (CED) score and their impact on ovarian function. Results were then examined using fixed-effect meta-analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Meta-analysis across the three independent cohorts showed a significant interaction effect (P = 3.0 × 10-4) between rs11668344 of BRSK1 (allele frequency = 0.34) among CCS treated with high-dose alkylating agents (CED score ≥8000 mg/m2), resulting in a 2.5-fold increased odds of a reduced ovarian function (lowest AMH tertile) for CCS carrying one G allele compared to CCS without this allele (odds ratio genotype AA: 2.01 vs AG: 5.00).

LIMITATIONS, REASONS FOR CAUTION

While low AMH levels can also identify poor responders in assisted reproductive technology, it needs to be emphasized that AMH remains a surrogate marker of ovarian function.

WIDER IMPLICATIONS OF THE FINDINGS

Further research, validating our findings and identifying additional risk-contributing genetic variants, may enable individualized counselling regarding treatment-related risks and necessity of fertility preservation procedures in girls with cancer.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the PanCareLIFE project that has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 602030. In addition, the DCOG-LATER VEVO study was funded by the Dutch Cancer Society (Grant no. VU 2006-3622) and by the Children Cancer Free Foundation (Project no. 20) and the St Jude Lifetime cohort study by NCI U01 CA195547. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Oncofertility care for newly diagnosed girls with cancer in a national pediatric oncology setting, the first full year experience from the Princess Máxima Center, the PEARL study

Background

Childhood cancer patients often remain uninformed regarding their potential risk of gonadal damage. In our hospital we introduced a five step standard oncofertility care plan for all newly diagnosed female patients aiming to identify, inform and triage 100% of patients and counsel 100% of patients at high risk (HR) of gonadal damage. This observational retrospective study (PEARL study) evaluated the use of this standard oncofertility care plan in the first full year in a national cohort.

Methods

The steps consist of 1)timely (preferably before start of gonadotoxic treatment) identification of all new patients, 2)triage of gonadal damage risk using a standardized gonadal damage risk stratification tool, 3)informing all patients and families, 4)counseling of a selected subset of girls, and 5) fertility preservation including ovarian tissue cryopreservation (OTC) in HR patients using amended Edinburgh criteria. A survey of the medical records of all girls newly diagnosed with cancer the first year (1-1-2019 until 31-12-2019) was conducted.

Results

Of 261 girls, 228 (87.4%) were timely identified and triaged. Triage resulted in 151 (66%) low(LR), 32 (14%) intermediate(IR) and 45 (20%) high risk(HR) patients. Ninety-nine families were documented to be timely informed regarding gonadal damage risk. In total, 35 girls (5 LR, 5 IR, 25 HR) were counseled by an oncofertility expert. 16/25 HR patients underwent fertility preservation (1 ovariopexy + OTC, oocyte cryopreservation (1 with and 1 without OTC) and 13 OTC). Fertility preservation did not lead to complications or delay of cancer treatment in any patient.

Conclusion

We timely identified and triaged most girls (88%) with cancer with a high risk of gonadal damage to be counseled for fertility preservation. We aim to optimize the oncofertility care plan and the standardized gonadal damage risk stratification tool based on this experience and these may be of value to other pediatric oncology centers.

Anti-Müllerian Hormone and Ovarian Morphology in Women With Hypothalamic Hypogonadism

CONTEXT

Different phenotypical features of women with hypothalamic hypogonadism (HH), also known as World Health Organization-1 anovulation, including ovarian morphology, have been scarcely described in large cohorts. Some studies have reported increased levels of anti-Müllerian hormone (AMH) in women with HH.

OBJECTIVE

To assess whether women with HH, compared with healthy controls, have increased serum levels of AMH and what proportion of these women erroneously meet the Rotterdam Criteria for Polycystic Ovarian Syndrome (PCOS).

DESIGN, SETTING AND PARTICIPANTS

Retrospective cohort study in a Dutch academic medical center including 83 women with neither anovulation nor menstrual cycle disorders (healthy controls), 159 women with HH and 3640 women with PCOS. Age matching was used between the HH and PCOS group (1:2 ratio) to create a second group consisting of 318 age-matched women with PCOS.

INTERVENTION

None.

MAIN OUTCOME MEASURES

AMH levels and ovarian morphology.

RESULTS

Median AMH serum levels for the HH group were 3.8 (<0.1-19.8), compared with 7.5 (<0.1-81.0) in the PCOS group and 1.9 (<0.1-21.5) in the control group (P < 0.001). In the HH group, 58 (36%) erroneously met the Rotterdam Criteria for PCOS (meeting 2 of 3 criteria).

CONCLUSIONS

AMH levels are increased in women with HH. We hypothesize that this increase, although there was no increase in follicle count, may be explained by the presence of a relatively large pool of antral follicles smaller than 2 mm in diameter, that are undetectable by transvaginal ultrasound. This study highlights the importance of measuring gonadotropins and estradiol before diagnosing a patient with PCOS.

Changes in Anti-Müllerian Hormone and Inhibin B in Children Treated for Cancer

Purpose: Diminished reproductive function can be a major late effect of childhood cancer treatment. This study evaluates the changes, and occurrence of possible recovery, in gonadal function markers in children treated for cancer. Methods: Gonadal function markers were measured before (T0), directly after (T1), and 1 year after (T2) end of treatment of childhood cancer. Anti-Müllerian hormone (AMH) was measured in girls and inhibin B in boys and compared to reference populations. Repeated measures analysis of variance and t-tests were employed for data analysis. Results: Baseline gonadal function markers (T0) at diagnosis were available in 129 girls and 150 boys. Paired gonadal function markers were available in 49 girls and 54 boys for T0-T1, and in 27 girls and 32 boys for T1-T2. Gonadal function markers were significantly lower than the reference population at each time point (p < 0.001). Post-menarcheal girls showed a decrease in AMH between T0 and T1 (standard deviation scores [SDS] -0.72 to -1.32, p = 0.007), and in the boys cohort, a decrease in inhibin B (SDS -1.14 to -1.43, p = 0.045) was observed. Impaired gonadal function levels (<5th percentile) at T1 were observed in 15 of 27 (56%) girls and in 15 of 32 (47%) boys. However, gonadal function had recovered at T2 in seven girls and six boys. Conclusion: Our data suggest that gonadal function is already compromised at diagnosis and is further decreased by childhood cancer treatment. Nevertheless, about half of the children with gonadal impairment recovered over time. Evaluation of gonadal function markers before 1 year after end of treatment may therefore be unreliable.

Genetic variation in gonadal impairment in female survivors of childhood cancer: a PanCareLIFE study protocol

Background

Improved risk stratification, more effective therapy and better supportive care have resulted in survival rates after childhood cancer of around 80% in developed countries. Treatment however can be harsh, and three in every four childhood cancer survivors (CCS) develop at least one late effect, such as gonadal impairment. Gonadal impairment can cause involuntary childlessness, with serious consequences for the well-being of CCS. In addition, early menopause increases the risk of comorbidities such as cardiovascular disease and osteoporosis. Inter-individual variability in susceptibility to therapy related gonadal impairment suggests a role for genetic variation.

Currently, only one candidate gene study investigated genetic determinants in relation to gonadal impairment in female CCS; it yielded one single nucleotide polymorphism (SNP) that was previously linked with the predicted age at menopause in the general population of women, now associated with gonadal impairment in CCS. Additionally, one genome wide association study (GWAS) evaluated an association with premature menopause, but no GWAS has been performed using endocrine measurements for gonadal impairment  as the primary outcome in CCS.

Methods

As part of the PanCareLIFE study, the genetic variability of chemotherapy induced gonadal impairment among CCS will be addressed. Gonadal impairment will be determined by anti-Müllerian hormone (AMH) levels or alternatively by fertility and reproductive medical history retrieved by questionnaire. Clinical and genetic data from 837 non-brain or non-bilateral gonadal irradiated long-term CCS will result in the largest clinical European cohort assembled for this late-effect study to date. A candidate gene study will examine SNPs that have already been associated with age at natural menopause and DNA maintenance in the general population. In addition, a GWAS will be performed to identify novel allelic variants. The results will be validated in an independent CCS cohort.

Discussion

This international collaboration aims to enhance knowledge of genetic variation which may be included in risk prediction models for gonadal impairment in CCS.

Perinatal risks in female cancer survivors: A population-based analysis

Background/objectives

Advances in cancer management have resulted in improved survival rates, particularly in children and young adults. However, treatment may adversely affect reproductive outcomes among female cancer survivors. The objective of this study was to investigate their risk of adverse perinatal outcomes compared to the general population.

Design/methods

We performed a population-based analysis, including all female cancer survivors diagnosed before the age of 40 years between 1981 and 2012. Pregnancy and perinatal complications were identified through linkage of the Scottish Cancer Registry with hospital discharge records based on the Community Health Index (CHI) database. We compared 1,629 female cancer survivors with a first ever singleton pregnancy after diagnosis, with controls matched on age, deprivation quintile, and year of cancer diagnosis selected from the general population (n = 8,899). Relative risks and 95%-confidence intervals of perinatal risks were calculated using log-binomial regression.

Results

Survivors were more likely to give birth before 37 weeks of gestation (relative risk (RR]) 1.32, 95%-CI 1.10–1.59), but did not show an increased risk of low birth weight (<2.5kg: RR 1.15, 95%-CI 0.94–1.39), and were less likely to give birth to offspring small for gestational age (RR 0.81, 95%-CI 0.68–0.98). Operative delivery and postpartum haemorrhage were more common but approached rates in controls with more recent diagnosis. The risk of congenital abnormalities was not increased (RR 1.01, 95%-CI 0.85–1.20).

Conclusion

Cancer survivors have an increased risk of premature delivery and postpartum haemorrhage, but their offspring are not at increased risk for low birth weight or congenital abnormalities. In recent decades there has been a normalisation of delivery method in cancer survivors, nevertheless careful management remains appropriate particularly for those diagnosed in childhood.

The Association of Handgrip Strength and Type 2 Diabetes Mellitus in Six Ethnic Groups: An Analysis of the HELIUS Study

We investigated whether ethnic differences in handgrip strength, a marker of poor muscle strength and quality, is a potential cause of ethnic disparities in type 2 diabetes mellitus. We included 2086 Dutch, 2216 South Asian Surinamese, 2084 African Surinamese, 1786 Ghanaian, 2223 Turkish and 2199 Moroccan origin participants from the HELIUS study. We analyzed ethnic differences in handgrip strength, and its association with type 2 diabetes mellitus using logistic regression analyses adjusted for socio-demographic factors, body composition and lifestyle factors. Additionally, we investigated whether handgrip strength explained the ethnic differences in type 2 diabetes mellitus. We found that handgrip strength differed significantly across ethnic groups. After full adjustment, we found an inverse association with type 2 diabetes mellitus (OR 0.95; 95% CI 0.92-0.97) that did not differ substantially between ethnic groups, men and among women, and lean and overweight individuals. The association was not affected by the measure used to define type 2 diabetes mellitus, but was attenuated by exclusion of people with known diabetes. The ethnic differences in type 2 diabetes mellitus were not explained by handgrip strength (e.g. the OR for the South Asian Surinamese vs. Dutch changed from 5.03; 3.69-6.68 to 4.87; 3.57-6.65). In conclusion, we found large ethnic differences in handgrip strength and a consistent association of low handgrip strength with prevalent type 2 diabetes mellitus. This suggests that handgrip strength may be investigated as a target for intervention or a marker to identify people at risk of type 2 diabetes mellitus.