Genetic effects of radiotherapy for childhood cancer

Elucidating the Transcriptional States of Spermatogenesis-Joint Analysis of Germline and Supporting Cell, Mice and Human, Normal and Perturbed, Bulk and Single-Cell RNA-Seq

In studying the molecular underpinning of spermatogenesis, we expect to understand the fundamental biological processes better and potentially identify genes that may lead to novel diagnostic and therapeutic strategies toward precision medicine in male infertility. In this review, we emphasized our perspective that the path forward necessitates integrative studies that rely on complementary approaches and types of data. To comprehensively analyze spermatogenesis, this review proposes four axes of integration. First, spanning the analysis of spermatogenesis in the healthy state alongside pathologies. Second, the experimental analysis of model systems (in which we can deploy treatments and perturbations) alongside human data. Third, the phenotype is measured alongside its underlying molecular profiles using known markers augmented with unbiased profiles. Finally, the testicular cells are studied as ecosystems, analyzing the germ cells alongside the states observed in the supporting somatic cells. Recently, the study of spermatogenesis has been advancing using single-cell RNA sequencing, where scientists have uncovered the unique stages of germ cell development in mice, revealing new regulators of spermatogenesis and previously unknown cell subtypes in the testis. An in-depth analysis of meiotic and postmeiotic stages led to the discovery of marker genes for spermatogonia, Sertoli and Leydig cells and further elucidated all the other germline and somatic cells in the testis microenvironment in normal and pathogenic conditions. The outcome of an integrative analysis of spermatogenesis using advanced molecular profiling technologies such as scRNA-seq has already propelled our biological understanding, with additional studies expected to have clinical implications for the study of male fertility. By uncovering new genes and pathways involved in abnormal spermatogenesis, we may gain insights into subfertility or sterility.

Consideration of hereditary effects in the radiological protection system: evolution and current status

PURPOSE

The purpose of this paper is to provide an overview of the methodology used to estimate radiation genetic risks and quantify the risk of hereditary effects as outlined in the ICRP Publication 103. It aims to highlight the historical background and development of the doubling dose method for estimating radiation-related genetic risks and its continued use in radiological protection frameworks.

RESULTS

This article emphasizes the complexity associated with quantifying the risk of hereditary effects caused by radiation exposure and highlights the need for further clarification and explanation of the calculation method. As scientific knowledge in radiation sciences and human genetics continues to advance in relation to a number of factors including stability of disease frequency, selection pressures, and epigenetic changes, the characterization and quantification of genetic effects still remains a major issue for the radiological protection system of the International Commission on Radiological Protection.

CONCLUSION

Further research and advancements in this field are crucial for enhancing our understanding and addressing the complexities involved in assessing and managing the risks associated with hereditary effects of radiation.

Congenital Malformations and Perinatal Deaths Among the Children of Atomic Bomb Survivors: A Reappraisal

From 1948 to 1954, the Atomic Bomb Casualty Commission conducted a study of pregnancy outcomes among births to atomic bomb survivors (Hiroshima and Nagasaki, Japan) who had received radiation doses ranging from 0 Gy to near-lethal levels. Past reports (1956, 1981, and 1990) on the cohort did not identify significant associations of radiation exposure with untoward pregnancy outcomes, such as major congenital malformations, stillbirths, or neonatal deaths, individually or in aggregate. We reexamined the risk of major congenital malformations and perinatal deaths in the children of atomic bomb survivors (n = 71,603) using fully reconstructed data to minimize the potential for bias, using refined estimates of the gonadal dose from Dosimetry System 2002 and refined analytical methods for characterizing dose-response relationships. The analyses showed that parental exposure to radiation was associated with increased risk of major congenital malformations and perinatal death, but the estimates were imprecise for direct radiation effects, and most were not statistically significant. Nonetheless, the uniformly positive estimates for untoward pregnancy outcomes among children of both maternal and paternal survivors are useful for risk assessment purposes, although extending them to populations other than the atomic bomb survivors comes with uncertainty as to generalizability.

The Likelihood of Adverse Pregnancy Outcomes and Genetic Disease (Transgenerational Effects) from Exposure to Radioactive Fallout from the 1945 Trinity Atomic Bomb Test

The potential health consequences of the Trinity nuclear weapon test of 16 July 1945 at Alamogordo, New Mexico, are challenging to assess. Population data are available for mortality but not for cancer incidence for New Mexico residents for the first 25 y after the test, and the estimates of radiation dose to the nearby population are lower than the cumulative dose received from ubiquitous natural background radiation. Despite the estimates of low population exposures, it is believed by some that cancer rates in counties near the Trinity test site (located in Socorro County) are elevated compared with other locations across the state. Further, there is a concern about adverse pregnancy outcomes and genetic diseases (transgenerational or heritable effects) related to population exposure to fallout radiation. The possibility of an intergenerational effect has long been a concern of exposed populations, e.g., Japanese atomic bomb survivors, survivors of childhood and adolescent cancer, radiation workers, and environmentally exposed groups. In this paper, the likelihood of discernible transgenerational effects is discounted because (1) in all large-scale comprehensive studies of exposed populations, no heritable genetic effects have been demonstrated in children of exposed parents; (2) the distribution of estimated doses from Trinity is much lower than in other studied populations where no transgenerational effects have been observed; and (3) there is no evidence of increased cancer rates among the scientific, military, and professional participants at the Trinity test and at other nuclear weapons tests who received much higher doses than New Mexico residents living downwind of the Trinity site.

Pregnancy in Breast Cancer Survivors

Safety of pregnancy occurring after breast cancer treatment has been studied largely, but it is still debatable. These studies have generally showed that overall and disease-free survival in breast cancer survivors with subsequent pregnancy is not less than those without future pregnancy . Also, breast cancer survivors treated with chemotherapy , radiation therapy, or both had no increased risk of congenital anomalies, single gene disorders, or chromosomal syndromes in their offspring. However, it appears that the incidence of preterm labor, low birth weight, and fetal anomalies is higher in these cases.These issues as well as safe time interval from breast cancer treatment to pregnancy , safe contraceptive method after breast cancer, counseling about pregnancy in survivors, and how to follow up the patient for breast cancer recurrence during pregnancy are discussed in this chapter.

The joy and duty of a marginal teratologist

On the occasion of this anniversary of the Society for Birth Defects Research and Prevention, I accept the invitation to offer personal reflections on the earlier days of the Society and the importance of the discipline. My focus is on what few contributions I have offered, but more, on the value of having the teratologist's perspective on other aspects of my career in medical genetics and genetic epidemiology. Treating my professional life as a development biologist (of which teratologists are a breed), I recount the institutions I have been at, but more importantly, the people I have been influenced by, more often than not accomplished teratologists. The one big thought I wish to leave is the primacy and criticality of being mentored and mentoring at ALL stages of a career.

Cryptorchidism after the Fukushima Daiichi Nuclear Power Plant accident:causation or coincidence?

Cryptorchidism (undescended testes) is among the most common congenital diseases in male children. Although many factors have been linked to the incidence of cryptorchidism, and testicular androgen plays a key role in its pathogenesis, the cause remains unknown in most cases. Recently, a Japanese group published a speculative paper entitled, "Nationwide increase in cryptorchidism after the Fukushima nuclear accident." Although the authors implicated radionuclides emitted from the Fukushima accident as contributing to an increased incidence of cryptorchidism, they failed to establish biological plausibility for their hypothesis, and glossed over an abundance of evidence and expert opinion to the contrary. We assessed the adequacy of their study in terms of design setting, data analysis, and its conclusion from various perspectives. Numerous factors must be considered, including genetic, environmental, maternal/fetal, and social factors associated with the reporting of cryptorchidism. Other investigators have established that the doses of external and internal radiation exposure in both Fukushima prefecture and the whole of Japan after the accident are too low to affect testicular descent during fetal periods;thus, a putative association can be theoretically and empirically rejected. Alternative explanations exist for the reported estimates of increased cryptorchidism surgeries in the years following Japan's 2011 earthquake, tsunami, and nuclear crisis. Data from independent sources cast doubt on the extent to which cryptorchidism increased, if at all. In any case, evidence that radionuclides from the Fukushima Daiichi Nuclear Power Plant could cause cryptorchidism is lacking.

Reproductive Function and Outcomes in Female Survivors of Childhood, Adolescent, and Young Adult Cancer: A Review

Some survivors of childhood, adolescent, and young adult cancer are at increased risk of gonadal dysfunction and adverse pregnancy outcomes. We reviewed currently available literature that evaluated reproductive function and pregnancy outcomes of female cancer survivors diagnosed before the age of 25 years. High-dose alkylating agent chemotherapy and abdominal/pelvic radiotherapy adversely affect gonadal function in a dose-related fashion, with older age at exposure conferring greater risk as a result of the age-related decline in ovarian reserve. Gonadal injury clinically manifests as ovarian hormone insufficiency (delayed or arrested puberty, premature ovarian insufficiency, or premature menopause) and infertility. The effect of molecular-targeted agents on ovarian function has not been established. For female cancer survivors who maintain fertility, overall pregnancy (relative risk, 0.67 to 0.81) and live birth rates (hazard ratio, 0.79 to 0.82) are lower than those in the general public. Pregnancy in cancer survivors also may be associated with risks to both the mother and the fetus related to miscarriage; preterm birth; and, rarely, cardiomyopathy. Women at risk for these complications require preconception assessment and counseling from both obstetricians and oncology providers. The risk for inherited genetic disease in offspring conceived after cancer treatment exposure is not increased. The optimization of reproductive outcomes and minimization of risks of pregnancy complications in survivors requires informed, risk-based assessment and monitoring.

Transgenerational effects of chemotherapy: Both male and female children born to women exposed to chemotherapy have fewer children

BACKGROUND

There is little known about the transgenerational effect of chemotherapy. For example, chemotherapy is known to decrease fecundity in women. But if women are able to have offspring after chemotherapy exposure, do these children also have decreased fecundity?

METHODS

This study is a retrospective cohort study utilizing the Utah Population Database (UPDB), a comprehensive resource that links birth, medical, death and cancer records for individuals in the state of Utah. The male and female children (F1 generation) of chemotherapy-exposed women (F0 generation) were identified. The number of live births (F2 generation) to this F1 generation was compared to two sets of chemotherapy-unexposed, matched controls using conditional Poisson regression models (regression coefficient, 95% confidence interval, P-value). The first unexposed was established using the general population and the second unexposed was established using first cousins to the F1 generation.

RESULTS

The exposed F1 individuals had 77.2% fewer children (-1.48; -2.51 to -0.70; p = 0.001) relative to the unexposed general population. F1 males had 86.9% fewer children (-2.03; -4.91 to -0.51; p = 0.005) and F1 females had 70.5% fewer children (-1.22; -2.40 to -0.36; p = 0.016). When comparing to their unexposed cousins, the F1 generation (both sexes combined) had 74.3% (-1.36; -2.82 to -0.29; p = 0.029) fewer children.

CONCLUSION

The sons and daughters (F1 generation) of chemotherapy-exposed women have fewer live births when compared to both matched, unexposed general population and cousin controls. Chemotherapy may have a transgenerational effect in exposed women which needs further investigation.

Why Genetic Effects of Radiation are Observed in Mice but not in Humans

Genetic effects from radiation have been observed in a number of species to date. However, observations in humans are nearly nonexistent. In this review, possible reasons for the paucity of positive observations in humans are discussed. Briefly, it appears likely that radiation sensitivity for the induction of mutations varies among different genes, and that the specific genes that were used in the past with the specific locus test utilizing millions of mice may have simply been very responsive to radiation. In support of this notion, recent studies targeting the whole genome to detect copy number variations (deletions and duplications) in offspring derived from irradiated spermatogonia indicated that the mutation induction rate per genome is surprisingly lower than what would have been expected from previous results with specific locus tests, even in the mouse. This finding leads us to speculate that the lack of evidence for the induction of germline mutations in humans is not due to any kind of species differences between humans and mice, but rather to the lack of highly responsive genes in humans, which could be used for effective mutation screening purposes. Examples of such responsive genes are the mouse coat color genes, but in human studies many more genes with higher response rates are required because the number of offspring examined and the radiation doses received are smaller than in mouse studies. Unfortunately, such genes have not yet been found in humans. These results suggest that radiation probably induces germline mutations in humans but that the mutation induction rate is likely to be much lower than has been estimated from past specific locus studies in mice. Whole genome sequencing studies will likely shed light on this point in the near future.

Ovarian and Uterine Functions in Female Survivors of Childhood Cancers

Adult survivors of childhood cancers are more prone to developing poor reproductive and obstetrical outcomes than their siblings and the general population as a result of previous exposure to chemotherapy and radiation during childhood. Chemotherapy drugs exert cytotoxic effects systemically and therefore can damage the ovaries, leading to infertility, premature ovarian failure, and, to a lesser extent, spontaneous abortions. They have very limited or no deleterious effects on the uterus that can be recognized clinically. By contrast, radiation is detrimental to both the ovaries and the uterus, thereby causing a greater magnitude of adverse effects on the female reproductive function. These include infertility, premature ovarian failure, miscarriage, fetal growth restrictions, perinatal deaths, preterm births, delivery of small-for-gestational-age infants, preeclampsia, and abnormal placentation. Regrettably, the majority of these adverse outcomes arise from radiation-induced uterine injury and are reported at higher incidence in the adult survivors of childhood cancers who were exposed to uterine radiation during childhood in the form of pelvic, spinal, or total-body irradiation. Recent findings of long-term follow-up studies evaluating reproductive performance of female survivors provided some reassurance to female cancer survivors by documenting that pregnancy and live birth rates were not significantly compromised in survivors, including those who had been treated with alkylating agents and had not received pelvic, cranial, and total-body irradiation. We aimed in this narrative review article to provide an update on the impact of chemotherapy and radiation on the ovarian and uterine function in female survivors of childhood cancer.

IMPLICATIONS FOR PRACTICE

Adult survivors of childhood cancers are more prone to developing a number of poor reproductive and obstetrical outcomes than their siblings and the general population as a result of previous exposure to chemotherapy and radiation during childhood. The impact of radiation therapy on the female genital system is greater than chemotherapy regimens because radiation is detrimental to both the uterus and the ovaries, whereas toxic effects of chemotherapy drugs are confined to the ovaries. Therefore, radiation-induced uterine damage accounts for most poor obstetrical outcomes in the survivors. These include infertility, miscarriages, stillbirths, fetal growth restrictions, preeclampsia, and preterm deliveries.

Strategies for Fertility Preservation in Female and Male Cancer Survivors

Improved survival rates and quality of life following modern cancer treatment have resulted in a growing number of patients requesting maintenance of reproductive capacity, both before and after completion of treatment. Several established options are currently available. In men, sperm banking should be offered as soon as the diagnosis of any malignant disease is established, irrespective of the expected cryosurvival rate. In such cases, conception can be achieved with frozen-thawed spermatozoa following either intrauterine insemination (IUI) or intracytoplasmic sperm injection (ICSI). In women, depending on the type of cancer, the presence of an adequate ovarian reserve, and time to delay cancer treatment, in vitro fertilization (IVF) with embryo cryopreservation constitutes a valid alternative. On the other hand, cryopreservation of mature oocytes following IVF/ICSI offers some advantages, but it is still limited by its low success rate. Emerging and exciting techniques of germ cell/gonadal tissue cryopreservation (banking) followed by autotransplantation have been clinically explored, particularly in women. Novel cryotechnologies of ovarian and testicular tissue have proven efficacious and new transplantation strategies promise improved results. However, only one live birth following autotransplanted frozen-thawed ovarian tissue has been established and there are still no pregnancies reported from autotransplanted cryopreserved testicular tissue in the human. Efficiency and safety of these techniques needs to be demonstrated. Methods for gamete in vitro maturation also need further development. Gonadal tissue cryopreservation and transplantation should be considered experimental in humans for the present time until greater evidence regarding efficacy and safety is accrued.

Risk for congenital anomalies in offspring of childhood, adolescent and young adult cancer survivors

Offspring of cancer survivors (CS) may be at risk for congenital anomalies due to the mutagenic therapies received by their parents. Our population-based cohort study aimed to investigate the risk for congenital anomalies in offspring of CS compared to offspring of their siblings. Using the Finnish Cancer Registry, Central Population Register, and Hospital Discharge Register, we identified hospital contacts due to congenital anomalies in 6,862 offspring of CS (early-onset cancer between 1953 and 2004) and 35,690 offspring of siblings. Associations between congenital anomalies and cancer were evaluated using generalized linear regression modelling. The ratio of congenital anomalies in offspring of CS (3.2%) was slightly, but non-significantly, elevated compared to that in offspring of siblings (2.7%) [prevalence ratio (PR) 1.07, 95% confidence interval (CI) 0.91-1.25]. When offspring of childhood and adolescent survivors (0-19 years at cancer diagnosis) were compared to siblings' offspring, the risk for congenital anomalies was non-significantly increased (PR 1.17, 95% CI 0.92-1.49). No such increase existed for offspring of young adult survivors (20-34 years at cancer diagnosis) (PR 1.01, 95% CI 0.83-1.23). The risks for congenital anomalies were elevated among offspring of CS diagnosed with cancer in the earlier decades (1955-1964: PR 2.77, 95% C I 1.26-6.11; and 1965-1974: PR 1.55, 95% C I 0.94-2.56). In our study, we did not detect an overall elevated risk for congenital anomalies in offspring of survivors diagnosed in young adulthood. An association between cancer exposure of the parent and congenital anomalies in the offspring appeared only for those CS who were diagnosed in the earlier decades.

Stillbirth and neonatal death among female cancer survivors: A national cohort study

The number of cancer survivors continues to increase worldwide. Many of these survivors have had children of their own. It is less well-known whether radiation therapy or chemotherapy could affect the risk of stillbirth and neonatal death for these children. To explore this research questions, we identified all women diagnosed with cancer between 1958 and 2012 from the Swedish Cancer Register and they were further linked to the Swedish Medical Birth Register to identify their subsequent child birth between 1973 and 2012. Multivariate logistic regression was used to estimate odds ratios and 95% confidence intervals for the association between stillbirth and neonatal death and maternal cancer diagnosis. As compared to the children without maternal cancer, the risk of stillbirth was significantly higher among children of female cancer survivors born within three years after cancer diagnosis with an OR of 1.92 (95% CI 1.03-3.57). The incidence of neonatal death did not show a significant change. For women with more than one pregnancy after cancer diagnosis, the risk of stillbirth and neonatal death was lower for the second child birth compared to the first child birth. Our study suggested that the risk of stillbirth was negatively associated with the time after cancer diagnosis, providing evidence that the adverse effect associated with cancer treatment may diminish with time.

Radiation occupational health interventions offered to radiation workers in response to the complex catastrophic disaster at the Fukushima Daiichi Nuclear Power Plant

The Fukushima Daiichi Nuclear Power Plant (NPP) 1 was severely damaged from the chain reaction of the Great East Japan Earthquake and Tsunami on 11 March 2011, and the consequent meltdown and hydrogen gas explosions. This resulted in the worst nuclear accident since the Chernobyl accident of 1986. Just as in the case of Chernobyl, emergency workers were recruited to conduct a wide range of tasks, including disaster response, rescuing activities, NPP containment, and radiation decontamination. This paper describes the types and efficacy of the various occupational health interventions introduced to the Fukushima NPP radiation workers. Such interventions were implemented in order to prevent unnecessary radiation overexposure and associated adverse health effects and work injuries. Less than 1% of all emergency workers were exposed to external radiation of >100 mSv, and to date no deaths or health adversities from radiation have been reported for those workers. Several occupational health interventions were conducted, including setting of new regulatory exposure limits, improving workers' radiation dosimetry, administration of stable iodine, running an occupational health tracking system, and improving occupational medicine and preventative care. Those interventions were not only vital for preventing unnecessary radiation, but also for managing other general health issues such as mental health, heat illness and infectious diseases. Long-term administration of the aforementioned occupational health interventions is essential to ensure the ongoing support and care for these workers, who were put under one of the most severe occupational health risk conditions ever encountered.

Germline minisatellite mutations in workers occupationally exposed to radiation at the Sellafield nuclear facility

Germline minisatellite mutation rates were investigated in male workers occupationally exposed to radiation at the Sellafield nuclear facility. DNA samples from 160 families with 255 offspring were analysed for mutations at eight hypervariable minisatellite loci (B6.7, CEB1, CEB15, CEB25, CEB36, MS1, MS31, MS32) by Southern hybridisation. No significant difference was observed between the paternal mutation rate of 5.0% (37 mutations in 736 alleles) for control fathers with a mean preconceptional testicular dose of 9 mSv and that of 5.8% (66 in 1137 alleles) for exposed fathers with a mean preconceptional testicular dose of 194 mSv. Subgrouping the exposed fathers into two dose groups with means of 111 mSv and 274 mSv revealed paternal mutation rates of 6.0% (32 mutations in 536 alleles) and 5.7% (34 mutations in 601 alleles), respectively, neither of which was significantly different in comparisons with the rate for the control fathers. Maternal mutation rates of 1.6% (12 mutations in 742 alleles) for the partners of control fathers and 1.7% (19 mutations in 1133 alleles) for partners of exposed fathers were not significantly different. This study provides evidence that paternal preconceptional occupational radiation exposure does not increase the germline minisatellite mutation rate and therefore refutes suggestions that such exposure could result in a destabilisation of the germline that can be passed on to future generations.

Radiation effects on human heredity

In experimental organisms such as fruit flies and mice, increased frequencies in germ cell mutations have been detected following exposure to ionizing radiation. In contrast, there has been no clear evidence for radiation-induced germ cell mutations in humans that lead to birth defects, chromosome aberrations, Mendelian disorders, etc. This situation exists partly because no sensitive and practical genetic marker is available for human studies and also because the number of people exposed to large doses of radiation and subsequently having offspring was small until childhood cancer survivors became an important study population. In addition, the genome of apparently normal individuals seems to contain large numbers of alterations, including dozens to hundreds of nonfunctional alleles. With the number of mutational events in protein-coding genes estimated as less than one per genome after 1 gray (Gy) exposure, it is unsurprising that genetic effects from radiation have not yet been detected conclusively in humans.

Radiation risk of individual multifactorial diseases in offspring of the atomic-bomb survivors: a clinical health study

There is no convincing evidence regarding radiation-induced heritable risks of adult-onset multifactorial diseases in humans, although it is important from the standpoint of protection and management of populations exposed to radiation. The objective of the present study was to examine whether parental exposure to atomic-bomb (A-bomb) radiation led to an increased risk of common polygenic, multifactorial diseases-hypertension, hypercholesterolaemia, diabetes mellitus, angina pectoris, myocardial infarction or stroke-in the first-generation (F1) offspring of A-bomb survivors. A total of 11,951 F1 offspring of survivors in Hiroshima or Nagasaki, conceived after the bombing, underwent health examinations to assess disease prevalence. We found no evidence that paternal or maternal A-bomb radiation dose, or the sum of their doses, was associated with an increased risk of any multifactorial diseases in either male or female offspring. None of the 18 radiation dose-response slopes, adjusted for other risk factors for the diseases, was statistically significantly elevated. However, the study population is still in mid-life (mean age 48.6 years), and will express much of its multifactorial disease incidence in the future, so ongoing longitudinal follow-up will provide increasingly informative risk estimates regarding hereditary genetic effects for incidence of adult-onset multifactorial disease.

Life after childhood cancer: marriage and offspring in adult long-term survivors--a population-based study in the Piedmont region, Italy

The majority of childhood cancer cases survive to adulthood. We describe the experience of marriage and reproduction as indicators of quality of life, in a population-based cohort of adult long-term survivors after early cancer reported to the Childhood Cancer Registry of Piedmont. The study included 1237 survivors with a malignant neoplasm diagnosed during 1967-2000 when aged 0-14 years, who attained age 18 years. Vital and marital status and number of offspring were assessed through the Vital Statistics Offices. Marriage and fertility deficits were estimated by comparison with the Piedmont population. Among the individuals included in this study, 919 (74.3%) never married and never lived as married. The marriage deficit was 32% [observed/expected 0.68; 95% confidence interval (CI): 0.55-0.83] in men and 18% (observed/expected 0.82; 95% CI: 0.68-0.98) in women. A total of 179 children were born to 120 women, with a fertility deficit of 41% (observed/expected 0.59; 95% CI: 0.51-0.69). In conclusion, the observed decrements in marriage in men and women and fertility in women suggest that efforts should be made to improve the recovery from physical and psychological traumas related to diagnosis and treatment of cancer.

Mortality among offspring of women diagnosed with cancer: a population-based cohort study

One in five cancers in women is diagnosed prior to and during a woman's fertile years. Our study evaluates mortality risks in offspring of mothers with history of cancer. From the Swedish Multi-generation Register and the Cancer Register, we identified all 174,893 children whose mother had been diagnosed with cancer between 1958 and 2001. We categorized offspring into those born before (>1 year before), around (within 1 year before and after diagnosis) and after (>1 year after) their mother's cancer diagnosis and compared their risks of death (standardized mortality ratios, SMRs) and causes of death to the background population. Overall, offspring of mothers diagnosed with cancer had no increased mortality risk (SMR, 1.00; 95% confidence interval [CI], 0.97-1.03). Increased mortality risks were found in offspring of mothers with tobacco-related cancers (head and neck, thoracic and cervical) (SMR, 1.23; 95% CI, 1.13-1.33), in children born around their mother's diagnosis (SMR, 1.66; 95% CI, 1.25-2.13) and in children born after their mother's hematopoietic cancer diagnosis (SMR, 2.07; 95% CI, 1.10-3.35). Compared to the background population, children born around their mother's diagnosis were more likely to die of congenital and perinatal conditions. Overall, offspring of women diagnosed with cancer were not at increased risk of death, except for certain subgroups. Timing of pregnancy in relation to diagnosis and cancer site modifies mortality risks in the offspring.

13-Cis retinoic acid can enhance the antitumor activity of non-replicating Sendai virus particle against neuroblastoma

Hemagglutinating virus of Japan-envelope (HVJ-E) is a drug delivery vector based on inactivated Sendai virus. Recently, antitumor activities were found for HVJ-E itself and clinical trials of HVJ-E for some malignant tumors are now ongoing. We investigated the in vitro and in vivo antitumor effects of HVJ-E against neuroblastoma, which is one of the most common malignant solid tumors in childhood. The sensitivity of human neuroblastoma cell lines to HVJ-E correlated with the expression level of gangliosides, Sialylparagloboside (SPG) and GD1a, receptors for HVJ. Among the cell lines, SK-N-SH was the most sensitive to HVJ-E in vitro and total SPG and GD1a expression was the highest. Complete eradication of subcutaneous tumors derived from SK-N-SH cells was achieved by intratumoral injection of HVJ-E in SCID mice and no recurrence was observed for more than 300 days after HVJ-E inoculation. In contrast, NB1 cells expressed the lowest amount of GD1a and SPG and were resistant to HVJ-E in vitro. The expression of GD1a increased by 13-cis retinoic acid (13cRA), which is a therapeutic drug for high risk neuroblastoma, thus leading to an improved sensitivity to HVJ-E in vitro. Only growth inhibition of the subcutaneous tumors derived from NB1 cells was achieved by HVJ-E in the SCID mice, but the combination of 13cRA and HVJ-E could achieve partial eradication of the xenograft and also lead to an improved prognosis. In conclusion, HVJ-E is a promising therapeutic modality for neuroblastoma and 13cRA can be used as an adjuvant to HVJ-E.

Fertility-preserving treatment options in patients with malignant hematological diseases

The number of patients of reproductive age diagnosed with various malignant hematological diseases increases every year. These patients undergo chemotherapy, radiotherapy, and various other treatments that may have gonadotoxic effects. The life expectancy of these patients is increasing rapidly due to the variety of treatment options. As such, an increasing number of patients-as well as their parents and spouses-express their concerns about the patient's fertility post treatment. In the present review it was aimed to provide an overview of current fertility-preserving treatment options and the future of fertility preservation.

Creating a continuum of care: integrating obstetricians and gynecologists in the care of young cancer patients

Cancer therapy can be lifesaving but significantly diminish female reproductive potential. This review provides an overview of the deleterious effects of cancer treatments on reproductive function, the fertility preservation options currently available for young women, and the outcomes of pregnancy after cancer treatment. In addition, special considerations for women who are diagnosed with cancer during pregnancy are discussed. To optimize the continuum of care for the patient, new corridors of communication between obstetricians, gynecologists, and oncology specialists must be developed to ensure the best outcomes for the patient, both in terms of cancer treatment and fertility preservation.

The use of next generation sequencing technology to study the effect of radiation therapy on mitochondrial DNA mutation

The human mitochondrial genome has an exclusively maternal mode of inheritance. Mitochondrial DNA (mtDNA) is particularly vulnerable to environmental insults due in part to an underdeveloped DNA repair system, limited to base excision and homologous recombination repair. Radiation exposure to the ovaries may cause mtDNA mutations in oocytes, which may in turn be transmitted to offspring. We hypothesized that the children of female cancer survivors who received radiation therapy may have an increased rate of mtDNA heteroplasmy mutations, which conceivably could increase their risk of developing cancer and other diseases. We evaluated 44 DNA blood samples from 17 Danish and 1 Finnish families (18 mothers and 26 children). All mothers had been treated for cancer as children and radiation doses to their ovaries were determined based on medical records and computational models. DNA samples were sequenced for the entire mitochondrial genome using the Illumina GAII system. Mother's age at sample collection was positively correlated with mtDNA heteroplasmy mutations. There was evidence of heteroplasmy inheritance in that 9 of the 18 families had at least one child who inherited at least one heteroplasmy site from his or her mother. No significant difference in single nucleotide polymorphisms between mother and offspring, however, was observed. Radiation therapy dose to ovaries also was not significantly associated with the heteroplasmy mutation rate among mothers and children. No evidence was found that radiotherapy for pediatric cancer is associated with the mitochondrial genome mutation rate in female cancer survivors and their children.

Pregnancy after successful cancer treatment: what needs to be considered?

Over the last decade, advances in oncology led to improved treatment results and increasing numbers of long-term cancer survivors. Fulfilling the desire to have children is important for many patients after cancer treatment. Consequently, oncologists, gynecologists and obstetricians are seeing more patients who wish to conceive after treatment. The necessary prerequisites that should be considered when supporting a planned pregnancy after cancer treatment are discussed in this article. The possible consequences of chemotherapy and radiotherapy on the course of pregnancy and the health of the offspring, as well as the interactions between cancer and pregnancy, are reviewed with the focus on childhood cancer, malignant lymphomas, and breast cancer. Despite chemo- or radiotherapy, neither the teratogenic risk nor the risk of adventitious cancers appears to be increased for the offspring of cancer survivors. However, there is a slightly higher risk of miscarriage after chemotherapy. In case of radiation to the uterus, there is a higher risk of premature birth, intrauterine growth retardation, and increased perinatal mortality. The effect is more pronounced after prepubertal radiation than for postpubertal radiation. The former cancer patient's desire to conceive can nevertheless be supported, given that pregnancy and birth are closely monitored.

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.

Genetic disease in the children of Danish survivors of childhood and adolescent cancer

PURPOSE

Preconception radiation and chemotherapy have the potential to produce germ cell mutations leading to genetic disease in the next generation. Dose-response relationships were evaluated between cancer treatments and untoward pregnancy outcomes.

PATIENTS AND METHODS

A case-cohort study was conducted involving 472 Danish survivors of childhood and adolescent cancer and their 1,037 pregnancies. Adverse outcomes included 159 congenital malformations, six chromosomal abnormalities, seven stillbirths, and nine neonatal deaths. Preconception radiation doses to the gonads, uterus, and pituitary gland and administered chemotherapy were quantified based on medical records and related to adverse outcomes using a generalized estimating equation model.

RESULTS

No statistically significant associations were found between genetic disease in children and parental treatment with alkylating drugs or preconception radiation doses to the testes in male and ovaries in female cancer survivors. Specifically, the risk of genetic disease was similar among the children of irradiated survivors when compared with nonirradiated survivors (relative risk [RR], 1.02; 95% CI, 0.59 to 1.44; P = .94). A statistically significant association between abdomino-pelvic irradiation and malformations, stillbirths, and neonatal deaths was not seen in the children of female survivors overall (P = .07) or in the children of mothers receiving high uterine doses (mean, 13.5 Gy; max, 100 Gy; RR, 2.3; 95% CI, 0.95 to 5.56).

CONCLUSION

Mutagenic chemotherapy and radiotherapy doses to the gonads were not associated with genetic defects in children of cancer survivors. However, larger studies need to be conducted to further explore potential associations between high-dose pelvic irradiation and specific adverse pregnancy outcomes.

Fertility sparing in cancer patients

Infertility can arise as a consequence of treatment of oncological conditions. As cancer survival rates continue to improve, many women will face infertility after successful treatment of their malignant diseases. This review summarizes the current state of different fertility preservation options in these patients. This review will discuss the premature ovarian failure and other adverse reproductive outcomes in female patients who receive chemotherapy and radiation. In addition, cancer-specific fertility preservation methods are presented. Embryo cryopreservation is a well established technique to preserve fertility. However, it requires delaying cancer treatment for two to six weeks and a partner or willingness to use donor sperm. When these criteria cannot be met, more experimental options include oocyte cryopreservation for later IVF and ovarian tissue cryopreservation. In-vitro maturation is a promising technology and can be applied in combination with oocyte or ovarian tissue cryopreservation. Ovarian transposition remains the standard option for women undergoing pelvic radiation. Lastly, the efficacy of GnRH analoga in ovarian protection during chemotherapy has still not been proved. As fertility preservation choices include both established and experimental methods, a highly individualized approach is required in the management of patients looking for fertility preservation options.

Assessment of heritable genetic effects using new genetic tools and sentinels in an era of personalized medicine

The challenge of estimating human health effects from damage to the germ line may be met in the genomic era. Understanding the genetic, as opposed to postconception developmental basis of birth defects is critical to their use in monitoring heritable genetic damage. The causes of common birth defects are analyzed here: mendelian genetic, multigenic, developmental, inherited, or combinational. Only a small fraction of these (noninherited, mendelian genetic) are likely to be informative relative to germ cell mutagenesis, and these won't be discernible against the general background of birth defects. Targeted genetic testing as part of personalized medicine could be integrated into a strategy for assessing germ cell alterations in populations. Thus, "sentinel mutations," as originally proposed by Mulvihill and Ceizel, need not be restricted to X-linked or dominant mutations or conditions visible at birth. Several new sentinels related to personalized medicine are proposed, based on health impact (likelihood of monitoring), frequency, and genetic target suitability (responsiveness to diverse mutational mechanisms). Candidates could include CYP genes (related to metabolism of xenobiotics) important in optimizing drug doses and avoiding adverse reactions. High frequency LDLR mutations (related to familial high cholesterol) predict myocardial infarction in approximately50% of individuals. The more common recessive genetic diseases (cystic fibrosis, phenylketonuria, and others) monitored in newborn screening programs could be informative given parental analysis. New opportunities for genetic analyses need to be coupled with epidemiological studies on environmental exposures. These could focus on adverse outcomes related to tobacco, the mostubiquitous and potent environmental mutagen.

Evaluation of the reproductive and developmental risks of caffeine

A risk analysis of in utero caffeine exposure is presented utilizing epidemiological studies and animal studies dealing with congenital malformation, pregnancy loss, and weight reduction. These effects are of interest to teratologists, because animal studies are useful in their evaluation. Many of the epidemiology studies did not evaluate the impact of the "pregnancy signal," which identifies healthy pregnancies and permits investigators to identify subjects with low pregnancy risks. The spontaneous abortion epidemiology studies were inconsistent and the majority did not consider the confounding introduced by not considering the pregnancy signal. The animal studies do not support the concept that caffeine is an abortafacient for the wide range of human caffeine exposures. Almost all the congenital malformation epidemiology studies were negative. Animal pharmacokinetic studies indicate that the teratogenic plasma level of caffeine has to reach or exceed 60 µg/ml, which is not attainable from ingesting large amounts of caffeine in foods and beverages. No epidemiological study described the "caffeine teratogenic syndrome." Six of the 17 recent epidemiology studies dealing with the risk of caffeine and fetal weight reduction were negative. Seven of the positive studies had growth reductions that were clinically insignificant and none of the studies cited the animal literature. Analysis of caffeine's reproductive toxicity considers reproducibility and plausibility of clinical, epidemiological, and animal data. Moderate or even high amounts of beverages and foods containing caffeine do not increase the risks of congenital malformations, miscarriage or growth retardation. Pharmacokinetic studies markedly improve the ability to perform the risk analyses.

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.

Paternal exposure to methotrexate and pregnancy outcomes

OBJECTIVE

To assess the risk of major malformation in the case of paternal exposure to methotrexate (MTX) at the time of conception.

METHODS

Using prospective data of our Teratology Information Service, we analyzed outcomes of paternal MTX exposure at the time of conception or up to 3 months before conception.

RESULTS

We report on the outcomes of 42 pregnancies involving 40 men treated with MTX at the time of conception. Twenty-three men were treated for an inflammatory disease (54.8%), 9 for psoriasis (21.4%), and 8 for a malignant disease (19.0%). Weekly dosages varied between 7.5 mg and 30 mg. The pregnancies resulted in 36 live births, 3 spontaneous abortions, and 3 voluntary abortions. No congenital malformation was observed at birth.

CONCLUSION

Based on our results and case reports in literature, paternal MTX exposure at the time of conception does not seem to raise any major concern for offspring.

Lauriston S. Taylor lecture: radiation epidemiology--the golden age and future challenges

Epidemiology is the study of the distribution and causes of disease in humans. Studies of human populations exposed to ionizing radiation have been conducted for nearly 100 y during the "Golden Age of Radiation Epidemiology." Radiation epidemiology is now so sophisticated that human studies are the basis for radiation protection standards and for compensation schemes in response to claims of ill health from prior exposures. The studies of exposed human populations are very broad and include not only the Japanese atomic bomb survivors, but also patients given radiotherapy for cancer, patients treated with radiation for nonmalignant disease, patients given diagnostic radiation, persons with intakes of radionuclides, workers exposed to occupational radiation, and communities exposed to environmental sources of radiation. But there is more to be learned, and future knowledge may be advanced from new and continued occupational studies of the early radiation workers, atomic veterans, medically exposed patients, and populations living in areas of high natural background radiation. The interaction between radiation and underlying genetic susceptibilities is an important emerging area of research. It is indeed an honor to be included among the Lauriston S. Taylor Lecturers.

Birth outcome in women with breast cancer, cutaneous malignant melanoma, or Hodgkin's disease: a review

BACKGROUND

Data on birth outcome in women diagnosed with cancer before, during, or shortly after pregnancy are very sparse. The purpose of this review was to summarize the existing epidemiologic evidence of the adverse effect of breast cancer, cutaneous malignant melanoma, and Hodgkin's disease on birth outcome.

METHODS

The MEDLINE database was used to review the literature systematically. Studies that examined the following outcomes were included: preterm birth, low birth weight, low birth weight at term, stillbirths, congenital abnormalities, male proportion of newborns, and mean birth weight. Studies were grouped according to whether the woman had been diagnosed with the specific cancer before, during, or shortly after pregnancy.

RESULTS

Few data exist on birth outcome in women with breast cancer, melanoma, or Hodgkin's disease. The overall results from the limited number of studies, which included a comparison group for birth outcome, were reassuring. However, for women diagnosed with breast cancer before pregnancy, the only 2 studies that included comparison groups for birth outcome had conflicting results regarding the risk of preterm birth and congenital abnormalities. Furthermore, a recent cohort study of birth outcome in women who were diagnosed with Hodgkin's disease before pregnancy indicated a slightly increased risk of congenital abnormalities among the newborns.

CONCLUSION

Overall, the existing studies offer reassuring results concerning the risks of adverse birth outcome for women diagnosed with breast cancer, melanoma, or Hodgkin's disease before, during or shortly after pregnancy. A limitation of most studies was the imprecise risk estimates caused by the small number of adverse birth outcomes and the lack of results stratified by treatment. Therefore, international collaboration is necessary in the future, to obtain more precise risk estimates for adverse birth outcomes, and to allow stratified analyses according to, for example, treatment.

Germline minisatellite mutations in survivors of childhood and young adult cancer treated with radiation

PURPOSE

To investigate minisatellite germline mutation rates in survivors of childhood and young adult cancer who received radiotherapy.

MATERIALS AND METHODS

DNA samples from 100 families, where one parent was a cancer survivor, were analysed for mutations at eight hypervariable minisatellite loci (B6.7, CEB1, CEB15, CEB25, CEB36, MS1, MS31, MS32) by Southern hybridisation.

RESULTS

No significant difference was observed between the paternal mutation rate of 5.6% in exposed fathers with a mean preconceptional testicular dose of 1.23 Gy (56 mutations in 998 informative alleles) and that of 5.8% in unexposed fathers (17 in 295 informative alleles). Subgrouping the exposed fathers into dose groups of < 0.10 Gy, 0.10-0.99 Gy, 1.00-1.99 Gy, ≥ 2.00 Gy revealed no significant differences in paternal mutation rate in comparison with the unexposed fathers. Maternal mutation rates of 1.6% in cancer survivor mothers with a mean preconceptional ovarian dose of 0.58 Gy (five mutations in 304 informative alleles) and 2.1% in unexposed mothers (21 in 987 informative alleles) were not significantly different. There were no differences in minisatellite mutation rates associated with treatment with chemotherapeutic agents.

CONCLUSIONS

This study provides evidence that preconception radiotherapy for childhood or early adulthood cancer does not increase the germline minisatellite mutation rate.

Reproductive outcomes for survivors of childhood cancer

Because of remarkable progress in therapy, long-term survival is expected for 80% of children and adolescents diagnosed with cancer. Infertility remains one of the most common and life-altering complications experienced by adults treated for cancer during childhood. Surgery, radiation, or chemotherapy that negatively affects any component of the hypothalamic-pituitary-gonadal axis may compromise reproductive outcomes in childhood cancer survivors. The risk of infertility is generally related to the tissues or organs involved in cancer and the specific type, dose, and combination of cytotoxic therapy. In addition to anticancer therapy, age at treatment, sex, and likely genetic factors influence the risk of permanent infertility. When possible, contemporary protocols limit cumulative doses of cytotoxic therapy in an effort to optimize reproductive potential. If sterilizing therapy is required for cancer control, then fertility preservation measures should be explored before initiation of therapy. For childhood cancer survivors who maintain fertility, health risks to offspring resulting from their cancer treatment are major concerns. Radiation affecting ovarian and uterine function has been linked to pregnancy complications, including spontaneous abortion, preterm labor, fetal malposition, and low birth weight. The risk of congenital malformations, genetic disorders, and cancer appears to be low, with the exception of cancer risk in offspring born to survivors with germline cancer-predisposing mutations. This review summarizes research about cancer treatment factors affecting fertility and pregnancy outcomes of childhood cancer survivors. The data presented should facilitate the delivery of preventive counseling and age- and sex-appropriate interventions to optimize reproductive outcomes in childhood cancer survivors.

G2 checkpoint control and G2 chromosomal radiosensitivity in cancer survivors and their families

Significant inter-individual variation in G(2) chromosomal radiosensitivity, measured as radiation-induced chromatid-type aberrations in the subsequent metaphase, has been reported in peripheral blood lymphocytes of both healthy individuals and a range of cancer patients. One possible explanation for this variation is that it is driven, at least in part, by the efficiency of G(2)-M checkpoint control. The hypothesis tested in the current analysis is that increased G(2) chromosomal radiosensitivity is facilitated by a less efficient G(2)-M checkpoint. The study groups comprised 23 childhood and adolescent cancer survivors, their 23 partners and 38 of their offspring (Group 1) and 29 childhood and young adult cancer survivors (Group 2). Following exposure to 0.5 Gy of 300 kV X-rays, lymphocyte cultures were assessed for both G(2) checkpoint delay and G(2) chromosomal radiosensitivity. In Group 1, the extent of G(2) checkpoint delay was measured by mitotic inhibition. No statistically significant differences in G(2) checkpoint delay were observed between the cancer survivors (P = 0.660) or offspring (P = 0.171) and the partner control group nor was there any significant relationship between G(2) checkpoint delay and G(2) chromosomal radiosensitivity in the cancer survivors (P = 0.751), the partners (P = 0.634), the offspring (P = 0.824) or Group 1 taken as a whole (P = 0.379). For Group 2, G(2) checkpoint delay was assessed with an assay utilising premature chromosome condensation to distinguish cell cycle stage. No significant relationship between G(2) checkpoint delay and G(2) chromosomal radiosensitivity was found (P = 0.284). Thus, this study does not support a relationship between G(2)-M checkpoint efficiency and variation in G(2) chromosomal radiosensitivity.

Fertility considerations in the management of gynecologic malignancies

GOALS

Gynecologic cancers represent a significant proportion of malignancies affecting women. Historically, cancer treatment focused primarily on eradicating disease, irrespective of the impact on fertility. The implementation of early detection protocols and advanced treatment regimens has resulted in improved prognosis for gynecologic cancer patients. With this improvement, more attention is now paid to quality-of-life issues. Fertility preservation (FP) has become an integral component in the selection and execution of gynecological cancer management. In this report we address gynecologic malignancies as they relate to future fertility potential.

METHODS

We review reproductive principles such as ovarian reserve, uterine function, cervical competence, and early obstetrical management, as well as available FP methods. In addition, we discuss the potential damage that cancer and cancer treatments can impart on the female reproductive system. We offer general recommendations regarding baseline screening tests useful in assessing the feasibility of FP. Lastly, cancer-specific FP methods are presented.

RESULTS

Oocyte quantity and quality naturally decline with advancing age. In most patients, the slope of decline steepens significantly after the age of 35. Reliable ovarian reserve measures exist and should be utilized to assess and triage potential candidates for FP. Advancements in FP, particularly in oocyte cryopreservation (OC), have improved the success rates associated with the techniques available to cancer patients. Currently, where successfully available, OC appears to be the preferred method for single women diagnosed with a gynecologic malignancy as it affords reproductive autonomy, whereas embryo cryopreservation using a donor gamete remains an alternative.

CONCLUSIONS

In gynecologic oncology, effective treatments to achieve cancer survival can compromise the ability to subsequently conceive and/or carry a child. Therefore, as the field of oncofertility continues to expand, a discussion regarding FP should be initiated when tailoring a cancer treatment protocol.

The heritability of G2 chromosomal radiosensitivity and its association with cancer in Danish cancer survivors and their offspring

PURPOSE

To investigate the relationship between chromosomal radiosensitivity and early-onset cancer under the age of 35 years and to examine the heritability of chromosomal radiosensitivity.

MATERIALS AND METHODS

Peripheral blood lymphocytes were cultured for 72 hours prior to being irradiated with 0.5 Gy, 300 kV X-rays. Colcemid was added to cultures 30 min post-irradiation. Cultures were harvested 90 min post-irradiation and analysed for chromatid gaps and breaks. Heritability was estimated using Sequential Oligogenic Linkage Analysis Routines (SOLAR) software and by segregation analysis.

RESULTS

Elevated radiosensitivity was seen for seven out of 29 (24.1%) cancer survivors, three out of 29 (10.3%) partners and 10 out of 53 (20.8%) offspring. Although the proportion of individuals displaying enhanced radiosensitivity was twice as high in both the cancer survivor and offspring groups than the partner controls, neither reached statistical significance. Heritability analysis of the radiosensitive phenotype suggested 57.9-78.0% of the variance could be attributed to genetic factors.

CONCLUSION

An association between G(2) chromosomal radiosensitivity and childhood and young adult cancer is suggested but was not statistically significant. In contrast, there is strong evidence for heritability of the radiosensitive phenotype. The cancer survivors included a broad range of malignancies and future studies should focus on specific cancers with known or likely faults in deoxyribonucleic acid (DNA) damage recognition and repair mechanisms.

Stillbirth and neonatal death in relation to radiation exposure before conception: a retrospective cohort study

BACKGROUND

The reproductive implications of mutagenic treatments given to children with cancer are not clear. By studying the risk of untoward pregnancy outcomes, we indirectly assessed the risk of transmission of germline damage to the offspring of survivors of childhood cancer who were given radiotherapy and chemotherapy.

METHODS

We did a retrospective cohort analysis, within the Childhood Cancer Survivor Study (CCSS), of the risk of stillbirth and neonatal death among the offspring of men and women who had survived childhood cancer. Patients in CCSS were younger than 21 years at initial diagnosis of an eligible cancer, were treated at 25 US institutions and one Canadian institution, and had survived for at least 5 years after diagnosis. We quantified the chemotherapy given to patients, and the preconception radiation doses to the testes, ovaries, uterus, and pituitary gland, and related these to the risk of stillbirth or neonatal death using Poisson regression analysis.

FINDINGS

Among 1148 men and 1657 women who had survived childhood cancer, there were 4946 pregnancies. Irradiation of the testes (16 [1%] of 1270; adjusted relative risk 0.8 [95% CI 0.4-1.6]; mean dose 0.53 Gy [SD 1.40]) and pituitary gland (17 [3%] of 510, 1.1 [0.5-2.4] for more than 20.00 Gy; mean dose 10.20 Gy [13.0] for women), and chemotherapy with alkylating drugs (26 [2%] of 1195 women, 0.9 [0.5-1.5]; ten [1%] of 732 men, 1.2 [0.5-2.5]) were not associated with an increased risk of stillbirth or neonatal death. Uterine and ovarian irradiation significantly increased risk of stillbirth and neonatal death at doses greater than 10.00 Gy (five [18%] of 28, 9.1 [3.4-24.6]). For girls treated before menarche, irradiation of the uterus and ovaries at doses as low as 1.00-2.49 Gy significantly increased the risk of stillbirth or neonatal death (three [4%] of 69, 4.7 [1.2-19.0]).

INTERPRETATION

Our findings do not support concern about heritable genetic changes affecting the risk of stillbirth and neonatal death in the offspring of men exposed to gonadal irradiation. However, uterine and ovarian irradiation had serious adverse effects on the offspring that were probably related to uterine damage. Careful management is warranted of pregnancies in women given high doses of pelvic irradiation before puberty.

FUNDING

Westlakes Research Institute, National Cancer Institute, and Children's Cancer Research Fund.

Fertility preservation in girls during childhood: is it feasible, efficient and safe and to whom should it be proposed?

BACKGROUND

In prepubertal and adolescent girls, fertility may be impaired by gonadotoxic treatments, repeat ovarian surgery or genetic disorders. Cryopreservation of ovarian cortex is an existing option to preserve fertility in these young girls at risk of premature ovarian failure (POF). The efficacy, feasibility and risks of ovarian cryopreservation in children must be assessed in order to validate the technique.

METHODS

Here, we conducted a review of ovarian cryopreservation in adults and, more specifically, in children using the PubMed databases. In addition, our own experience with ovarian cryopreservation in children was evaluated and compared with the literature.

RESULTS

Analysis of the literature and six published series on ovarian cryopreservation in children, as well as our own series of 58 cases, show that there is no reason to doubt its efficacy in this young population. However, no consensus has yet been reached on the indications for the technique. Indeed, with existing models, the real risk of POF may be over- or underestimated.

CONCLUSION

Our review suggests that ovarian cortex cryopreservation is feasible and as safe as comparable operative procedures in children. Although no births have yet resulted from freeze-thawing of prepubertal ovarian cortex, the results of this approach in adults are encouraging. However, the absence of consensus on the indications for fertility preservation, as well as the optimal timing and quantity of ovarian cortex for cryopreservation, should be taken into consideration when discussing fertility issues with girls at risk of POF and their parents.

Comparison of germ line minisatellite mutation detection at the CEB1 locus by Southern blotting and PCR amplification

Identification of de novo minisatellite mutations in the offspring of parents exposed to mutagenic agents offers a potentially sensitive measure of germ line genetic events induced by ionizing radiation and genotoxic chemicals. Germ line minisatellite mutations (GMM) are usually detected by hybridizing Southern blots of unamplified size-fractionated genomic DNA with minisatellite probes. However, this consumes a relatively large amount of DNA, requires several steps and may lack sensitivity. We have developed a polymerase chain reaction (PCR)-based GMM assay, which we applied to the hypermutable minisatellite, CEB1. Here, we compare the sensitivity and specificity of this assay with the conventional Southern hybridization method using DNA from 10 spouse pairs, one parent of each pair being a survivor of cancer in childhood, and their 20 offspring. We report that both methods have similar specificity but that the PCR method uses 250 times less DNA, has fewer steps and is better at detecting GMM with single repeats provided that specific guidelines for allele sizing are followed. The PCR GMM method is easier to apply to families where the amount of offspring DNA sample is limited.