No Long-Term Increase in Sperm Aneuploidy Rates after Anticancer Therapy

Risk of Congenital Malformations in Children Born Before Paternal Cancer

Background

Increased risk of congenital malformations in children fathered by men treated for cancer might be due to mutagenicity of cancer therapies. Finding of increased malformation prevalence in offspring born before paternal cancer would indicate a treatment-independent mechanism.

Methods

Through national registries, we obtained data on singletons born in Sweden from 1994 to 2014 (n = 1 796 160) and their fathers and mothers (1 092 950/1 092 011). Men with cancer (n = 23 932) fathered 26 601 and 9926 children before and after cancer diagnosis, respectively. Associations between paternal cancer, diagnoses retrieved from the Swedish Cancer Register, and offspring malformations, based on Swedish Medical Birth Register data, were estimated by logistic regression.

Results

Children conceived before paternal cancer had a statistically significantly increased risk of all malformations (odds ratio [OR] = 1.08, 95% confidence interval [CI] = 1.02 to 1.15, P = .016, 3.8% vs 3.4%) and major malformations (OR = 1.09, 95% CI = 1.01 to 1.18, P = .03, 2.4% vs 2.1%). Eye and central nervous system cancers were associated with the highest risk of all malformations (OR = 1.30, 95% CI = 1.04 to 1.61, P = .02, 4.5% vs 3.4%). A similar trend was seen for testicular cancer. The malformation rates among children conceived before and after paternal cancer diagnosis were similar.

Conclusions

The association between paternal cancer and risk of malformations in the offspring is not solely due to mutagenic effects of cancer therapy. The increase in prevalence of birth anomalies among children of fathers with malignancy might be due to cancer per se or a common underlying paternal factor, for example, genomic instability.

Sperm DNA Damage in Cancer Patients

Fertility is a growing healthcare issue for a rising number of cancer survivors. In men, cancer itself and its treatment can negatively affect spermatogenesis by targeting the dividing spermatogonia and their cellular environment, ultimately leading to a reduction of testicular germ cells and sperm count. Experimental data and prospective longitudinal studies have shown that sperm production can recover after cancer treatment. But despite this, yet unpredictable, recovery in sperm production, cancer survivors are more at risk to produce sperm with aneuploidy, DNA damage, abnormal chromatin structure, and epigenetic defects even 2 years post-treatment. Sperm DNA alteration is of clinical concern, as these patients may father children or seek assisted reproduction technologies (ART) using gametes with damaged genome that could result in adverse progeny outcomes. Interestingly, large cohort studies revealed lower birth rate but no significant impact on the health of the children born from male cancer survivors (naturally or using ART). Nevertheless, a better understanding of how cocktail of chemotherapy and new anticancer agents affect spermatogenesis and sperm quality is needed to reduce side effects. Moreover, developing new fertility preservation strategies is essential as sperm cryopreservation before treatment is currently the only option but does not apply for prepubertal/young postpubertal patients.

Fatherhood and Sperm DNA Damage in Testicular Cancer Patients

Testicular cancer (TC) is one of the most treatable of all malignancies and the management of the quality of life of these patients is increasingly important, especially with regard to their sexuality and fertility. Survivors must overcome anxiety and fears about reduced fertility and possible pregnancy-related risks as well as health effects in offspring. There is thus a growing awareness of the need for reproductive counseling of cancer survivors. Studies found a high level of sperm DNA damage in TC patients in comparison with healthy, fertile controls, but no significant difference between these patients and infertile patients. Sperm DNA alterations due to cancer treatment persist from 2 to 5 years after the end of the treatment and may be influenced by both the type of therapy and the stage of the disease. Population studies reported a slightly reduced overall fertility of TC survivors and a more frequent use of ART than the general population, with a success rate of around 50%. Paternity after a diagnosis of cancer is an important issue and reproductive potential is becoming a major quality of life factor. Sperm chromatin instability associated with genome instability is the most important reproductive side effect related to the malignancy or its treatment. Studies investigating the magnitude of this damage could have a considerable translational importance in the management of cancer patients, as they could identify the time needed for the germ cell line to repair nuclear damage and thus produce gametes with a reduced risk for the offspring.

Patients with multiple morphological abnormalities of the sperm flagella due to DNAH1 mutations have a good prognosis following intracytoplasmic sperm injection

STUDY QUESTION

Does DNAH1 status influence intracytoplasmic sperm injection (ICSI) outcomes for patients with multiple morphological abnormalities of the sperm flagella (MMAF)?

SUMMARY ANSWER

Despite a highly abnormal morphology, sperm from MMAF patients with DNAH1 mutations have a low aneuploidy rate and good nuclear quality, leading to good embryonic development following ICSI and a high pregnancy rate.

WHAT IS KNOWN ALREADY

Teratozoospermia represents a heterogeneous group including a wide range of phenotypes. Among all these qualitative defects, a flagellar phenotype called MMAF is characterized by a mosaic of morphological abnormalities of the flagellum, including coiled, bent, irregular, short or/and absent flagella, mainly due to the absence of the axonemal central pair microtubules. We previously demonstrated that homozygous mutations in the DNAH1 gene, encoding an inner arm heavy chain dynein, are frequently found in patients with MMAF (28% of the patients from the initial cohort). Numerous studies have reported an increased rate of aneuploidy and a poor sperm nuclear quality related to sperm flagellar abnormalities, which could impede ICSI outcome. Moreover, success rates after ICSI may be influenced by the type of ultrastructural flagellar defects and/or by the gene defects carried by the patients.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study included 6 infertile males with MMAF due to deleterious homozygous DNAH1 mutations and their respective spouses, who underwent 9 ISCI cycles, with 16 embryos being transferred. ICSI results were compared with two control populations of 13 MMAF men without DNAH1 mutations and an aged-matched control group of 1431 non-MMAF couples. All ICSI attempts took place between 2000 and 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Clinical and biological data were collected from patients treated for infertility at the CPSR les Jasmins in Tunis (Tunisia). We compared the ICSI outcomes obtained with couples including DNAH1 mutated and nonmutated patients and non-MMAF couples. For the analysis of the chromosomal status, fluorescence in situ hybridization (FISH) analyses were performed on sperm cells from 3 DNAH1-mutated patients and from 29 fertile control subjects. Sperm chromatin condensation and DNA fragmentation were evaluated using aniline blue staining and TUNEL assays, respectively, on sperm cells from 3 DNAH1-mutated men and 6 fertile controls.

MAIN RESULTS AND THE ROLE OF CHANCE

There was a significantly increased proportion of disomy XY and 18 in sperm from DNAH1 mutated patients compared with fertile controls (1.52 versus 0.28%, P = 0.0001 and 0.64 versus 0.09%, P = 0.0001). However, there were no statistically significant differences among sperm from the two groups in their frequencies of either 13, 21, XX or YY disomy or diploidy. Measures of DNA compaction and fragmentation demonstrated a good nuclear sperm quality among DNAH1 mutated men. The overall fertilization, pregnancy and delivery rates of couples including DNAH1 mutated men were of 70.8, 50.0 and 37.5%, respectively. There were no statistically significant differences in any of these parameters compared with the two control groups (P > 0.05).

LIMITATIONS, REASONS FOR CAUTION

A limitation of this study is the small number of DNAH1-mutated patients available and the low number of genes identified in MMAF. Further genetic studies are warranted to identify other MMAF-inducing genes to better characterize the genetic etiology of the MMAF phenotype and to improve the management of patients diagnosed with flagellar defects.

WIDER IMPLICATIONS OF THE FINDINGS

MMAF patients with DNAH1 mutations have low aneuploidy rates and good nuclear sperm quality, explaining the high pregnancy rate obtained with these patients. Good ICSI results were obtained for both MMAF groups (DNAH1 mutated and nonmutated), suggesting that patients presenting with asthenozoospermia due to flagellar defects have a good ICSI prognosis irrespective of their genotype. The majority of MMAF cases currently remain idiopathic with no genetic cause yet identified. In depth genetic analysis of these patients using next generation sequencing should reveal new causal genes. Subsequent genotype phenotype analyses could improve advice and care provided to MMAF patients.

STUDY FUNDING/COMPETING INTERESTS

None of the authors have any competing interest. This work is part of the project 'Identification and Characterization of Genes Involved in Infertility (ICG2I)', funded by the program GENOPAT 2009 from the French Research Agency (ANR) and the MAS-Flagella project, financed by the French ANR and the Direction Générale de l'Offre de Soins (DGOS).

Sperm aneuploidy in infertile male patients: a systematic review of the literature

Males with abnormal karyotypes and subgroups of fertile and infertile males with normal karyotypes may be at risk of producing unbalanced or aneuploid spermatozoa. Biological, clinical, environmental and other factors may also cause additional sperm aneuploidy. However, increased risk of sperm aneuploidy is directly related to chromosomally abnormal embryo production and hence to poor reproductive potential. This systemic literature review focuses on the identification of these males because this is an essential step in the context of assisted reproduction. This research may allow for a more personalised and, hence, more accurate estimation of the risk involved in each case, which in turn will aid genetic counselling for affected couples and help with informed decision-making.

Impact of chemotherapy and radiotherapy for testicular germ cell tumors on spermatogenesis and sperm DNA: a multicenter prospective study from the CECOS network

OBJECTIVE

To determine the consequences of adjuvant testicular germ cell tumor treatment (TGCT) on sperm characteristics and sperm DNA, and to evaluate the predictors of sperm recovery.

DESIGN

Multicenter prospective longitudinal study of patients analyzed before treatment and after 3, 6, 12, and 24 months.

SETTING

University hospitals.

PATIENT(S)

One hundred twenty-nine volunteer TGCT patients and a control group of 257 fertile men.

INTERVENTION(S)

Routine semen analyses, sperm DNA, and chromatin assessments.

MAIN OUTCOME MEASURE(S)

Comparisons of mean sperm characteristics before and after treatment, with sperm recovery analyzed by the Kaplan-Meier method.

RESULT(S)

The quantitative and qualitative sperm characteristics decreased after treatment, with lowest values at 3 and 6 months and with variations according to treatment type. The mean total sperm count recovered to pretreatment values at 12 months after treatment after two or fewer bleomycin, etoposide, and cisplatin (BEP) cycles, but not after radiotherapy or more than two BEP cycles. Only the treatment modalities and pretreatment sperm production were related to recovery of the World Health Organization reference sperm values. An increased proportion of patients had elevated high sperm DNA stainability at 6 months after radiotherapy.

CONCLUSION(S)

Adjuvant treatments for testicular germ cell tumor have drastic effects on spermatogenesis and sperm chromatin quality. These new data on both the recovery period according to treatment modalities and the post-treatment chromatin status of sperm are useful tools for counseling patients wishing to conceive.

Congenital anomalies in the children of cancer survivors: a report from the childhood cancer survivor study

PURPOSE

Children with cancer receive mutagenic treatments, which raises concern about the potential transmissibility of germline damage to their offspring. This question has been inadequately studied to date because of a lack of detailed individual treatment exposure assessment such as gonadal radiation doses.

METHODS

Within the Childhood Cancer Survivor Study, we performed a retrospective cohort analysis of validated cases of congenital anomalies among 4,699 children of 1,128 male and 1,627 female childhood cancer survivors. We quantified chemotherapy with alkylating agents and radiotherapy doses to the testes and ovaries and related these exposures to risk of congenital anomalies using logistic regression.

RESULTS

One hundred twenty-nine children had at least one anomaly (prevalence = 2.7%). For children whose mothers were exposed to radiation or alkylating agents versus neither, the prevalence of anomalies was 3.0% versus 3.5% (P = .51); corresponding figures were 1.9% versus 1.7% (P = .79) for the children of male survivors. Neither ovarian radiation dose (mean, 1.19 Gy; odds ratio [OR] = 0.59; 95% CI, 0.20 to 1.75 for 2.50+ Gy) nor testicular radiation dose (mean, 0.48 Gy; OR = 1.01; 95% CI, 0.36 to 2.83 for 0.50+ Gy) was related to risk of congenital anomalies. Treatment with alkylating agents also was not significantly associated with anomalies in the children of male or female survivors.

CONCLUSION

Our findings offer strong evidence that the children of cancer survivors are not at significantly increased risk for congenital anomalies stemming from their parent's exposure to mutagenic cancer treatments. This information is important for counseling cancer survivors planning to have children.

Sperm banking and the cancer patient

The current concepts, recommendations, and principles of sperm banking as it pertains to the comprehensive care of young men of reproductive age with cancer are reviewed. Obstacles to sperm banking are addressed as well as future directions for fertility-preserving technologies. All cancer therapies-chemotherapy, radiation, and surgery-are potential threats to a man's reproductive potential. In addition, cancer itself can impair spermatogenesis. Thus, sperm cryopreservation prior to initiating life-saving cancer treatment offers men and their families the best chance to father biologically related children and should be offered to all men with cancer before treatment. Better patient and provider education, as well as deliberate, coordinated strategies at comprehensive cancer care centers are necessary to make fertility preservation for male cancer patients a priority during pretreatment planning.

Effects of anti-neoplastic treatment on sperm aneuploidy rate in patients with testicular tumor: a longitudinal study

OBJECTIVE

The adjuvant radio/chemotherapy, usually employed after orchidectomy in patients with testicular tumors, allows a long-term survival with a consequent increased request for fertility. However, little is known about the effects of the anti-neoplastic treatment on sperm cytogenetic asset. Therefore, this prospective, longitudinal study was designed to evaluate the effects of radio- and/or chemotherapy on sperm chromosome.

METHODS

Eleven patients with testicular tumor were enrolled and underwent sperm aneuploidy rate evaluation before and after 3, 6, 9, 12, 18, 24, and 36 months from radio- and/or chemo-therapy ending. A double and triple multicolor fluorescence in-situ hybridizations for chromosomes 8, 12, 18, X and Y were used to evaluate the sperm aneuploidy rate. To define normal sperm aneuploidy rate, 18 healthy, normozoospermic men were selected as controls.

RESULTS

Before treatment, testicular tumor patients had a higher total sperm aneuploidy rate compared with normal men. Total sperm aneuploidy rate showed a slight, but statistically significant increase 6 months after anti-neoplastic treatment. This increase was mainly related to the high sperm aneuploidy rate found in 2 patients which remained elevated up to 12 months in both of them.

CONCLUSION

These results showed that anti-neoplastic treatment caused only slight and transient sperm malsegregation events in patients with testicular tumor. However, since a subset of them had an elevated sperm aneuploidy rate for about 1 yr, we suggest to counsel them to refrain from fatherhood for this length of time.

Risk of birth abnormalities in the offspring of men with a history of cancer: a cohort study using Danish and Swedish national registries

Background

The potential mutagenic effects of cancer therapies and the growing number of young male cancer survivors have given rise to concern about the health of their offspring.

Methods

We identified all singleton children born alive in Denmark between 1994 and 2004 and in Sweden between 1994 and 2005 (n = 1 777 765). Of the 8670 children with a paternal history of cancer, 8162 were conceived naturally and 508 were conceived using assisted reproductive technologies (ARTs) (in vitro fertilization or intracytoplasmatic sperm injection). Of the 1 769 0795 children without a paternal history of cancer, 25 926 were conceived using ARTs. Associations between paternal history of cancer and risk of adverse birth outcomes of children conceived naturally or by ARTs were investigated using log-linear binomial models, yielding risk ratios (RRs) with 95% confidence intervals (CIs). All statistical tests were two-sided.

Results

The offspring of male cancer survivors were more likely to have major congenital abnormalities than the offspring of fathers with no history of cancer (RR = 1.17, 95% CI = 1.05 to 1.31, P = .0043, 3.7% vs 3.2%). However, the mode of conception (natural conception or ARTs) did not modify the association between paternal history of cancer and risk of congenital abnormalities (natural conception, RR = 1.17, 95% CI = 1.04 to 1.31; ARTs, RR = 1.22, 95% CI = 0.80 to 1.87, P_interaction = .84).

Conclusion

We observed a statistically significant but modest increase in the risk of major congenital abnormalities among offspring of males with a history of cancer, independent of the mode of conception.

Fertility treatment in male cancer survivors

The present study reviews the use of assisted reproductive technology in male cancer survivors and their partners. As antineoplastic treatment with chemotherapy or radiation therapy, has the potential of inducing impairment of spermatogenesis through damage of the germinal epithelium, many male cancer survivors experience difficulties in impregnating their partners after treatment. The impairment can be temporary or permanent. While many cancer survivors regain spermatogenesis months to years after treatment, some become infertile with a-, oligo- or azoospermia. An option to secure the fertility potential of young cancer patients is to cryopreserve semen before cancer treatment for later use. A desired pregnancy may be obtained in couples where the husband has a history of cancer, using assisted reproductive technology with either fresh or cryopreserved/thawed semen. Successful outcomes have been obtained with intrauterine insemination (IUI) as well as in vitro fertilization (IVF) with or without the use of intracytoplasmic sperm injection (ICSI). In conclusion, male cancer survivors and their partners who have failed to obtain a pregnancy naturally within a reasonable time frame after end of treatment should be referred to a fertility clinic.

Sperm DNA integrity in testicular cancer patients

BACKGROUND

We evaluated the impact of testicular germ cell cancer (TGCC), its treatment and length of follow-up on sperm DNA integrity.

METHODS

In 96 TGCC patients, semen was collected at specific intervals until 5 years after treatment. Sperm DNA integrity was assessed by the sperm chromatin structure assay (SCSA, n = 193) and by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL, n = 159) assay. Results were expressed as DNA fragmentation index (DFI). Controls comprised of 278 military conscripts.

RESULTS

Post-surgery testicular cancer (TC) patients did not differ from controls. Compared with pretreatment values, radiotherapy induced a transient increase in SCSA(DFI) (medians: 12 versus 19%; P = 0.03), normalizing after 3-5 years. One year or more after therapy, 5/13 (38%) of normozoospermic, irradiated patients had SCSA(DFI) >27% compared with 7% of normozoospermic controls (P = 0.002). More than two cycles of chemotherapy decreased DFI 3-5 years post-therapy (median SCSA(DFI): 12 versus 9.1%, P = 0.02; median TUNEL(DFI): 11 versus 7.5%, P = 0.03).

CONCLUSION

Irradiation increases sperm DNA damage 1-2 years after treatment, and 38% of irradiated patients with normozoospermia had high (>27%) DNA damage, which may affect the sperm-fertilizing ability. TC per se is not associated with an increase of DFI, and DFI is reduced by three or more cycles of chemotherapy.

Germ cell tumors

PURPOSE OF REVIEW

This review provides an overview of some of the recent pre-clinical and clinical developments in germ cell tumors.

RECENT FINDINGS

Recent epidemiological studies highlight the variations in the geographic and ethnic distribution of germ cell tumors and the changing incidence of seminoma versus nonseminoma in the population. Additional studies are continuing to identify risk factors for germ cell tumors. Expression profiling, both at the gene and protein levels, is beginning to identify, at the molecular level, some of the factors associated not only with germ cell pluripotency but also with the different histologic subtypes of germ cell tumors. Work in the area of identifying potentially new serum tumor markers in germ cell tumor, as well as the role of the traditional tumor markers in predicting outcome to therapy is ongoing. Data is emerging on the role of positron emission tomography in evaluating residual lesions in seminoma. Evolving data on chemotherapy, radiation, and surgery further complements and clarifies information on these treatment modalities, and their potential toxicities, in the management of germ cell tumors.

SUMMARY

Ongoing preclinical and epidemiological studies highlight the complexities underlying germ cell tumor pathogenesis. With enhanced understanding of some of these processes, treatments, particularly for advanced stages, will continue to evolve.