Subclinical depletion of primordial follicular reserve in mice treated with cyclophosphamide: clinical importance and proposed accurate investigative tool

Strengths and limitations of using repeat-dose toxicity studies to predict effects on fertility

The upcoming European chemicals legislation REACH (Registration, Evaluation, and Authorisation of Chemicals) will require the risk assessment of many thousands of chemicals. It is therefore necessary to develop intelligent testing strategies to ensure that chemicals of concern are identified whilst minimising the testing of chemicals using animals. Xenobiotics may perturb the reproductive cycle, and for this reason several reproductive studies are recommended under REACH. One of the endpoints assessed in this battery of tests is mating performance and fertility. Animal tests that address this endpoint use a relatively large number of animals and are also costly in terms of resource, time, and money. If it can be shown that data from non-reproductive studies such as in-vitro or repeat-dose toxicity tests are capable of generating reliable alerts for effects on fertility then some animal testing may be avoided. Available rat sub-chronic and fertility data for 44 chemicals that have been classified by the European Union as toxic to fertility were therefore analysed for concordance of effects. Because it was considered appropriate to read across data for some chemicals these data sets were considered relevant for 73 of the 102 chemicals currently classified as toxic to reproduction (fertility) under this system. For all but 5 of these chemicals it was considered that a well-performed sub-chronic toxicity study would have detected pathology in the male, and in some cases, the female reproductive tract. Three showed evidence of direct interaction with oestrogen or androgen receptors (linuron, nonylphenol, and fenarimol). The remaining chemicals (quinomethionate and azafenidin) act by modes of action that do not require direct interaction with steroid receptors. However, both these materials caused in-utero deaths in pre-natal developmental toxicity studies, and the relatively low NOAELs and the nature of the hazard identified in the sub-chronic tests provides an alert for possible effects on fertility (or early embryonic development), the biological significance of which can be ascertained in a littering (e.g. 2-generation) study. From the chemicals reviewed it would appear that where there are no alerts from a repeat-dose toxicity study, a pre-natal developmental toxicity study and sex steroid receptor binding assays, there exists a low priority for animal studies to address the fertility endpoint. The ability for these types of tests to provide alerts for effects on fertility is clearly dependent on the mode of action of the toxicant in question. Further work should therefore be performed to determine the 'failure rate' of this type of approach when applied to a larger group of chemicals with diverse modes of action.

Cortical fibrosis and blood-vessels damage in human ovaries exposed to chemotherapy. Potential mechanisms of ovarian injury

BACKGROUND

Chemotherapy destroys primordial follicles and can lead to ovarian atrophy. Although reports indicate that apoptosis is the mechanism responsible for follicle loss, additional pathways can be involved. This study investigates the damage in human ovaries after administration of non-sterilizing doses of chemotherapy.

METHODS

In a blind study, pathological changes in ovarian tissue harvested for cryopreservation were evaluated. The study group comprised young non-sterile cancer patients, previously exposed to chemotherapy who were (mean +/- SD), when compared with non-exposed patients.

RESULTS

Thirty-five cancer patients aged 28.7 +/- 6.74; 17 were previously exposed to non-sterilizing chemotherapy and 18 were not. In all samples, primordial follicles were present. In previously exposed patients, damage to cortical blood vessel and proliferation of small vessels was observed. The cortex showed focal areas of fibrosis with disappearance of follicles (sensitivity 76%, positive predictive value 75% for <37 years old patients). Older patients, not exposed to chemotherapy (5/7) showed similar pathological changes.

CONCLUSIONS

Injury to blood vessels and focal ovarian cortical fibrosis are aspects of ovarian damage caused by chemotherapy. These findings indicate a potential additional mechanism of damage to the direct apoptotic effect of chemotherapy on follicles. The possibility that these changes are involved in ageing ovaries should be further investigated.

Fertility preservation options for women with malignancies

Cancer is not rare in younger women. There has been a remarkable improvement in the survival rates due to progress in cancer treatment. The necessary treatment for most of the common cancer types occurring in younger women implies either removal of the reproductive organs or cytotoxic treatment that could partially or definitively affect reproductive function. Early loss of ovarian function not only puts the patients at risk for menopause-related complications at a very young age, but is also associated with loss of fertility. Further, women in the western hemisphere have been delaying initiation of childbearing to later in life. The results of these changes have led to an increase in patients facing the risk of premature ovarian failure, and therefore seeking help in preserving their fertility. This increase in demand has resulted in a proliferation of techniques to preserve fertility. Indeed, the number of options is increasing; some are more established procedures, such as embryo cryopreservation, and some are still experimental, such as ovarian cryopreservation. Because of the variations in type and dose of chemotherapy, the type of cancer, the time available before onset of treatment, the patient's age and the partner status, each case is unique and requires a different strategy of fertility preservation.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall the potential early loss of ovarian function secondary to radiotherapy and/or chemotherapy for cancer at a young age; explain the increasing demands for fertility preservation; and summarize the limited number of proven, safe, and efficacious methods.

Fertility preservation in young women undergoing breast cancer therapy

Breast cancer accounts for one third of all neoplasms seen in reproductive-age women and affects tens of thousands of women each year in that age group. The adjuvant chemotherapy regimens used for the treatment commonly affect fertility and cause premature ovarian failure. There have been recent advances in the field of fertility preservation, which can allow many of these breast cancer survivors to have children in the future. The most established option is embryo cryopreservation; oocyte cryopreservation can be considered in single women. Both of these approaches require approximately 2 weeks of ovarian stimulation beginning with the onset of the patient's menstrual cycle. Thus, it is crucial that these patients are referred to appropriate assisted reproduction centers as soon as they are diagnosed with breast cancer. Recently developed ovarian stimulation protocols using tamoxifen and letrozole can be used to increase the margin of safety in these patients. When and if a breast cancer patient does not have time to undergo ovarian stimulation prior to chemotherapy, ovarian cryopreservation for future autotransplantation can be offered as the last resort. The benefit of ovarian protection by gonadotropin-releasing hormone analogues is unproven and unlikely, and thus this treatment should not be offered as the sole method of fertility preservation.

Ovarian tissue cryopreservation and transplantation: a review

The review covers current options for ovarian tissue cryopreservation and transplantation and provides a systematic review of the existing literature from the last 10 years, taking into account all previously published reviews on the subject. The different cryopreservation options available for fertility preservation in cancer patients are embryo cryopreservation, oocyte cryopreservation and ovarian tissue cryopreservation. The choice depends on various parameters: the type and timing of chemotherapy, the type of cancer, the patient's age and the partner status. The different options and their results are discussed, as well as their putative indications and efficacy. The review concludes that advances in reproductive technology have made fertility preservation techniques a real possibility for patients whose gonadal function is threatened by premature menopause, or by treatments such as radiotherapy, chemotherapy or surgical castration.

Müllerian inhibiting substance as a novel biomarker of cisplatin-induced ovarian damage

Müllerian inhibiting substance (MIS) has been investigated as a possible serum biomarker in human aging to estimate the number of female germ cells remaining. Cisplatin is an effective chemotherapeutic agent that is associated with ovarian injury. In this study, we tested the hypothesis that decreasing serum MIS can serve as a biomarker of ovarian damage after cisplatin. Adult female rats were treated with saline, 4.5, or 6.0 mg/kg cisplatin. The serum MIS levels were lower in both cisplatin groups, in a dose-related fashion. The ovarian lysates of both cisplatin groups had less MIS than control. Immunofluorescence analysis showed that the percentage of MIS-positive follicles was lower in the 6.0 mg/kg group. TUNEL assays showed that there was a dose related increase in the number of apoptotic follicles in the cisplatin groups. In summary, a decrease in serum MIS could serve as a biomarker to discriminate the degree of ovarian damage after cisplatin. These data are the first to establish in the rat that ovarian injury due to a chemotherapeutic agent could be monitored with the non-invasive serum biomarker MIS.

Imminent ovarian failure in childhood cancer survivors

The aim of this study was to investigate reproductive history and the prevalence of imminent ovarian failure (IOF) in female childhood cancer survivors. Reproductive history and ovarian function were evaluated by questionnaires (n=124) and by measurement of follicle stimulating hormone (FSH) and oestradiol (E2) levels (n=93). IOF was defined as FSH>10 IU/l or E2>0.28 nmol/l on day 3 of the menstrual cycle, or FSH>12.4 IU/l on day 7 of the pill-free interval. IOF was demonstrated in 22.6% of the participants and correlated with age at diagnosis (P<0.005) and age at study (P=0.036). IOF correlated inversely with methotrexate (P=0.046). The incidence of miscarriages (22.7%) and recurrent miscarriages (7.3%) was increased. The male/female (M/F) ratio of the offspring was decreased. In conclusion, female childhood cancer survivors are at risk for IOF. If pregnant, the risk of (recurrent) miscarriages is increased. The M/F ratio in the offspring is decreased.

Characterizing the ovotoxicity of cyclophosphamide metabolites on cultured mouse ovaries

Cyclophosphamide (CPA) is reported to target dormant primordial ovarian follicles in rodents and humans. However, mechanistic studies are complicated due to the complex ovarian structure. We present here the characterization of the sensitivity of ovaries to CPA metabolites and the timing of morphological alterations induced by phosphoramide mustard (PM) in an in vitro system. Intact mouse ovaries (postnatal-day-4) were cultured in vitro and exposed to multiple breakdown products of CPA on day 0 (d0). Tissues were cultured up to d8, and then follicle counts and immunohistochemistry were performed. 4-Hydroperoxy-CPA (4-HC), a precursor of an activated form of CPA, and PM depleted primordial and primary follicles (> or =1 microM and > or =3 microM, respectively, p < 0.05); acrolein had effects on follicle numbers only under continuous exposure (> =30 microM); carboxycyclophosphamide and 4-ketocyclophosphamide reduced primordial and small primary follicles only at high concentrations (100 microM). PM-induced follicle loss became significant (p < 0.05) by d1 or d2 following exposures to 10 microM or 3 microM PM, respectively, as determined by the numbers of pyknotic or TUNEL-positive follicles. Cellular targets were oocytes in the smallest follicles, but granulosa cells in large primary follicles. TUNEL staining was observed in both cell types, but caspase-3, a marker of apoptosis, was absent from primordial follicles. In addition, a pan-caspase inhibitor could not prevent follicle losses when administered prior to PM. Thus, brief exposures to 4-HC or PM are sufficient to induce permanent follicle loss in ovaries, and PM is likely the ultimate ovotoxicant. Furthermore, the cell death pathway is likely caspase-independent.

The Use of an Open-freezing System with Self-seeding for Cryopreservation of Mouse Ovarian Tissue

Chemoradiotherapy in young women with cancer has substantially improved life expectancy in these patients, but these treatments often cause infertility. One method of preserving fertility is to cryopreserve ovarian tissue. In this study, an automatic open-vessel freezing system with self-seeding was tested for cryopreservation of murine ovarian tissue; the mouse is a species widely used in human and veterinary medical research. The freezing system concerned, is used for cryopreservation of oocytes and embryos in Europe. Twenty severe combined immunodeficiency (SCID) mice were ovariectomized. The ovarian tissue was either directly transplanted heterotopically into the neck muscle (group 1, n = 6) or cryopreserved after equilibration with 1.5 M dimethylsulphoxide and propanediol. After thawing, the tissue was transplanted in SCID mice (group 2, n = 6). Before and after thawing, a part of the ovarian tissue was examined with the LIVE/DEAD fluorescent viability staining. The count of follicles revealed intact (fresh 24.1%/thawed 21.7%), impaired (fresh 35.1%/thawed 35.4%), and dead follicles (fresh 40.8%/thawed 42.9%). The healthy follicular loss because of the cryopreservation was 10.0%. All recipient mice were killed after 3 weeks. Transplanted ovarian tissue was found macroscopically in all mice. Histological examination showed several growing follicles in all developmental phases in both groups of SCID mice [group 1 (fresh grafts): 315 +/- 76.3 (mean +/- SD); group 2 (cryopreserved grafts): 237 +/- 63.4]. These results demonstrate that the use of an open-freezing system allows the survival of cryopreserved mouse ovarian tissue.

Damage to ovarian development and function

Ovarian function in women can be compromised by exposure to toxic environmental factors. Chemicals that affect ovarian function can act through direct effects on hormone action (ovary) or by interference with steroid hormone action (hypothalamus and/or pituitary). These effects can cause problems in the form of infertility. Alternatively, ovarian toxicants can directly cause ovarian failure by extensive follicular destruction. This targeting can result in loss of ovarian steroid hormones, eventual ovarian failure (menopause), and ultimate disruption of neuroendocrine feedback causing increased levels of FSH and LH. This article provides an overview of chemicals that in animal studies have been identified to cause disrupted ovarian function with a focus on the sites of targeting by which these disruptions occur. In predicting the impact of environmental factors on reproductive function in women, it is critical to gain a better appreciation of the physiological consequences resulting from the potential variety of mechanisms by which toxicants can disrupt ovarian function. This article attempts to provide such a perspective within the context of specific chemicals for which ovarian sites of toxicity have been identified.

Effect of chemotherapy on primordial follicular reserve of rat: an animal model of premature ovarian failure and infertility

AIM

To determine the effect of paclitaxel and cisplatin in the reduction of primordial follicular reserve in rat.

MATERIAL AND METHODS

Thirty young female rats were divided randomly into three groups of 10 rats each. Paclitaxel 7.5 mg/kg and cisplatin 5 mg/kg were administered intraperitoneally in a single dose sterile technique to paclitaxel (n=10), and cisplatin (n=10) groups, and sterile saline solution was given to a control group (n=10). To assess the effects of chemotherapeutic agents on the primordial follicles, the rats were oophorectomised 7 days after the administration of chemotherapeutic agents. Haematoxylin and eosin staining was used to determine the number of primordial follicles. Primordial follicles were identified by the presence of an oocyte encapsulated partially or completely by a single layer of flattened follicular cells without a theca layer at the ovarian cortex.

RESULTS

The number of primordial follicles in the control group was 23.1 +/- 16.1 follicles. The number of primordial follicles were decreased significantly in both paclitaxel and cisplatin groups compared to control group (10.3 +/- 13.0 and 13.9 +/- 15.2 follicles, respectively) (P=0.001 and P=0.01, respectively). The difference in the number of primordial follicles between the paclitaxel and cisplatin groups was insignificant (P=0.465).

CONCLUSION

The administration of high dose paclitaxel and cisplatin to young rats causes the depletion of primordial follicles. However, no significant difference was observed between the two agents.

Efficacy of in vitro fertilization after chemotherapy

OBJECTIVE

To evaluate if in vitro fertilization (IVF) with embryo cryopreservation can be proposed to patients immediately after one or two regimens of chemotherapy.

DESIGN

Retrospective study.

SETTING

Academic research center and IVF unit.

PATIENT(S)

Eleven young patients diagnosed with cancer between September 1999 and April 2003 who wanted to preserve their fertility via IVF.

INTERVENTION(S)

Stimulation and IVF before or soon after chemotherapy treatment.

MAIN OUTCOME MEASURE(S)

The number and quality of embryos obtained after stimulation in cancer patients undergoing IVF before or soon after chemotherapeutic treatment.

RESULT(S)

Four patients underwent IVF in the interval between two regimens of chemotherapy. Two of them had no follicular development; one underwent follicular puncture but no oocytes were retrieved; and, in one, six oocytes were harvested but only one good quality embryo was obtained. In the seven patients who underwent IVF before starting chemotherapy, between 4 and 11 embryos were obtained per patient, the majority being good quality embryos.

CONCLUSION(S)

Because the efficacy of IVF is dramatically reduced after even one round of chemotherapy, IVF should be performed before chemotherapy. For those who require immediate chemotherapy, ovarian tissue cryopreservation and/or oocyte cryopreservation could be used before treatment.

Fertility preservation and pregnancy outcome after malignancy

PURPOSE OF REVIEW

The overall survival and cure rates of patients with childhood and adult malignancies have improved dramatically, but cancer treatment can be associated with diminished reproductive potential. However, research on the preservation of fertility in these patients has given patients new options. This article discusses the mechanisms of reproductive failure after cancer therapy and the currently available fertility preservation strategies.

RECENT FINDINGS

Ovarian transposition is still a viable option if radiotherapy is to be used alone. Modifications in assisted reproductive technology that decrease peak estradiol levels are ideal for breast cancer survivors. Embryo freezing technology offers excellent pregnancy rates. Oocyte freezing is available for women without a partner, but there is more limited experience with this technique. Understanding the concepts of graft function after the autotransplantation of frozen-thawed ovarian tissue has resulted in great strides in the technical requirements for success.

SUMMARY

Gonadotropin-releasing hormone analogues are the only available medical protection means for gonadotoxic chemotherapy. Assisted reproductive technology offers excellent results, but the protocols require a delay in implementing chemotherapy. Despite recent reports of embryo development after the transplantation of cryopreserved-thawed ovarian tissue, clinical experience is limited and the technique remains experimental.

Chemotherapy-Induced Ovarian Failure

Thanks to improvements in treatment regimens, more and more patients are now surviving cancer. However, cancer survivors are faced with the serious long-term effects of the different modalities of cancer treatments. One of these adverse effects is chemotherapy-induced irreversible damage to the ovarian tissues, which leads to premature ovarian failure and its resulting consequences such as hot flashes, osteoporosis, sexual dysfunction and the risk of infertility. Chemotherapy-induced ovarian failure (or chemotherapy-induced premature menopause) affects the quality of life of female cancer survivors. Although there is no clear definition of chemotherapy-induced ovarian failure, irreversible amenorrhoea lasting for several months (>12 months) following chemotherapy and a follicle stimulating hormone level of > or = 30 MIU/mL in the presence of a negative pregnancy test seems to be an appropriate characterisation. Different chemotherapy agents, alkylating cytotoxics in particular, have the potential to cause progressive and irreversible damage to the ovaries. The result of this damage is a state of premature ovarian failure, with progressive declining of estrogen levels, decreasing bone mass and an increased risk of fractures. Historically, hormonal replacement therapy (HRT) has been used to treat menopausal problems in the general population, but concerns about the potential of estrogen to increase the risk of breast cancer in women at high-risk or increase the risk of recurrence in cancer survivors, have forced physicians to utilise alternative treatments. This review discusses some of the newer therapies that are now available to provide appropriate symptom control, avoid complications such as fractures and possibly prevent infertility by making the ovarian epithelium less susceptible to cytotoxic agents.

Fertility in female cancer survivors: pathophysiology, preservation and the role of ovarian reserve testing

The improved long-term survival of adolescents and young women treated for cancer has resulted in an increased focus on the effects of chemotherapy on ovarian function and its preservation. These women may seek advice and treatment regarding their reproductive status, including ways of preserving their fertility and preventing a premature menopause--factors that can have a profound impact on their quality of life. This article comprehensively reviews ovarian reserve testing (ORT) in general. Special emphasis is placed on patients with cancer, including the pathophysiology of gonadal damage following chemotherapy, fertility preservation and the potential role of ORT. Baseline parameters of ovarian reserve [FSH LH, estradiol, inhibin B and anti-Mullerian hormone (AMH)] have not yet performed sufficiently well in predicting poor outcome in assisted reproduction, but biochemical markers of ovarian reserve appear to be better than chronological age. Inhibin B and AMH show potential for future use. Dynamic testing appears to show much promise, especially stimulated levels of inhibin B and estradiol. The most promising tests of ovarian reserve are the biophysical markers, where total antral follicle count was found to be most discriminatory followed by ovarian volume. Combination of biochemical, biophysical and clinical markers of ovarian reserve may also improve predictive capacity. However, there is a lack of data pertinent to ORT in cancer. As yet there is no single clinically useful test to predict ovarian reserve accurately. Patients with cancer represent a distinct cohort who have particular concerns about their future fertility and the possibility of a premature menopause, they can benefit greatly from knowledge of their functional ovarian reserve. Large, prospective, randomized, adequately controlled studies specific to different geographical areas are required in a control population of comparable reproductive age to determine the potential role of ORT in clinical practice.

Incidence of chemotherapy-induced amenorrhea depending on the timing of treatment by menstrual cycle phase in women with early breast cancer

BACKGROUND

The aim of this study was to characterize the factors associated with chemotherapy-induced amenorrhea (CIA) and to examine whether the phase of the menstrual cycle at chemotherapy start could affect the rate of CIA in premenopausal women with early breast cancer.

METHODS

CIA was defined as the cessation of menses for at least 3 months during or after chemotherapy. Menstrual phase was defined as days 1-6, follicular phase as days 7-14, luteal phase as days 15-20 and premenstrual phase as days 21-28. Univariate and multivariate predictors of CIA were examined.

RESULTS

Among 111 premenopausal women, univariate analysis showed a higher incidence of CIA in patients treated in the follicular phase rather than in other menstrual cycle phases (67.6% compared with 45.5%; P=0.03). The rate of CIA increased with age: 65.2% and 45.8% in patients aged >42 and </=42 years, respectively (P=0.05). Upon multivariate analysis these differences remained statistically significant and duration of chemotherapy of more than six cycles correlated significantly with the incidence of CIA (P=0.03).

CONCLUSIONS

The major implication of this analysis is that the timing of treatment within the menstrual cycle may potentially modulate the onset of CIA. This work and its future confirmation using prospective randomized trials would be useful in predicting the likelihood of CIA and in counseling breast cancer patients, especially those with a good prognosis who benefit less from chemical castration.

Thalidomide-induced amenorrhea: Case report and literature review

OBJECTIVE

To report on a patient with thalidomide-induced amenorrhea and review the literature on the effect of thalidomide on ovarian function.

DESIGN

Case report and literature review.

SETTING

University medical center.

PATIENT(S)

A twenty-eight-year-old woman referred for a 2-year history of amenorrhea.

INTERVENTION(S)

History, physical examination, laboratory evaluation of the patient, and subsequent medical therapy. Literature review performed by using OVID/Medline and PubMed search strategies.

MAIN OUTCOME MEASURE(S)

Diagnosis and appropriate management of thalidomide-induced amenorrhea.

RESULT(S)

Elevated pituitary gonadotropins, other labs normal. All known causes of hypergonadotropic amenorrhea were excluded.

CONCLUSION(S)

Thalidomide induces hypergonadotropic amenorrhea. Although this effect appears to be reversible, the long-term effect of thalidomide on ovarian reserve is unclear.

Reduced ovarian function in long-term survivors of radiation- and chemotherapy-treated childhood cancer

Seventy percent of children with cancer survive. Radiation and chemotherapy may, however, impair ovarian function. The aim of this population-based study was to achieve a comprehensive knowledge of the degree of ovarian damage. Ovarian function was evaluated in 100 childhood cancer survivors and 21 controls of similar age. Menstrual cycle pattern was recorded, and strictly timed ovarian sonography and hormonal assessment were performed. The median age of the survivors was 5.4 yr (range, 0.1-15.3) at the time of diagnosis and 25.7 yr (18.5-44.4) at study entry. Seventeen survivors with premature ovarian failure had follicle-depleted or nondetectable ovaries, elevated FSH and LH, and immeasurable inhibin B. Thirteen survivors used oral contraception. Survivors with spontaneous menstrual cycles (n = 70) had smaller ovarian volume per ovary than controls (median, 4.8 vs. 6.8 cm(3); P < 0.001) and a lower number of antral follicles per ovary (median, 7.5 vs. 11; P < 0.001). Further, they had lower inhibin B levels than controls (median, 94 vs. 111 pg/ml; P = 0.03) and higher estradiol levels (median, 0.12 vs. 0.08 pM; P = 0.04). Multiple linear regression analysis was performed to predict the total antral follicle number per ovary, and it showed a reduced number with ovarian irradiation (beta = -0.40, P < 0.001), alkylating chemotherapy (beta = -0.25, P = 0.01), older age at diagnosis (beta = -0.25, P = 0.01), and longer time period off treatment (beta = -0.19, P = 0.044). One in every six female survivors may develop premature ovarian failure. In survivors with spontaneous menstrual cycles, the results indicate a diminished ovarian reserve. Consequently, cessation of fertility may occur much earlier than anticipated. Adult survivors with spontaneous cycles should be informed hereof to plan childbearing.

Central causes of hypogonadism--functional and organic

Whether caused by environmental factors, lesions, genetic mutations, drug interactions, or unknown origins, the path of the central causes of hypogonadism frequently leads back to the GnRH pulse generator. In some cases, the cause can be unequivocally traced to a single factor, such as some of the congenital syndromes previously described. In most instances, however, hypogonadism is occult or functional. Because of the wide spectrum and complexity of underlying causes, a definitive diagnosis, especially in functional causes of the disorder, is not always attainable.

Protecting female fertility from cancer therapy

Recent advances in cancer therapy have improved the long-term survival of young cancer patients who are then commonly faced with iatrogenic infertility and premature ovarian failure. Preservation of fertility potential has thus become a major goal and could be realized by preventing ovarian toxicity or by cryopreservation of reproductive cells (i.e. oocytes, embryos) and tissues (i.e. ovarian cortex). GnRH analogs prevent chemotherapy-induced-ovarian-damage in rats, however human results are controversial. Anti-apoptotic agents (i.e. sphingosine-1-phosphate) may present an innovative treatment to prevent oocyte destruction during cancer therapy. Although cryopreservation of mouse oocytes is successful, the results obtained in other mammalian species were worse, probably due to their extreme sensitivity to suboptimal conditions during the process of cryopreservation. This resulted in low oocyte survival and fertilization rates, a high incidence of polyploidy, and poor embryonic developmental ability. Ovarian tissue cryopreservation is currently considered as the optimal procedure for follicle banking. Transplantation offers the best prospect of using frozen-thawed ovarian tissue, since no reliable ovarian in-vitro culture technology exists.

Fertility options for female cancer patients: facts and fiction

OBJECTIVE

To review the latest progress in the prevention of ovarian failure induced by chemo/radiotherapy, as well as the latest advances in culture technology and transplantation of frozen-thawed ovarian tissue.

DESIGN

The English-language literature was searched with PubMed and related references.

CONCLUSION(S)

The development of combination chemotherapy and radiotherapy has improved the long-term survival of young cancer patients who are then frequently faced with iatrogenic ovarian failure and its consequences. The use of prior and concomitant GnRH analogs with chemotherapy offers encouraging results in animal studies with regard to prevention of ovarian failure. Adequately controlled research projects are needed to define the utility of GnRHa cotreatment in women cancer patients exposed to prolonged chemotherapy. Ovarian tissue cryopreservation is the optimal procedure for follicle banking. Theoretic options include returning the banked tissue back to the original pedicle so that pregnancy could be achieved naturally. Alternatively, the tissue can be grafted to a heterotopic site, either as an autograft (i.e., rectus abdominis muscle sheath) or as a xenograft (i.e., immunodeficient mice). Follicles could also be grown in vitro. Until reliable ovarian culture technology becomes available, autologous transplantation offers the best prospect of using frozen-thawed ovarian tissue. A primary concern, however, is the issue of microscopic metastatic disease to the ovary and the possibility of tumor reimplantation. Areas of research should focus on optimizing the freeze/thaw procedure for ovarian tissue, minimizing the ischemia-reperfusion injury after transplantation, and detecting minimal residual disease in ovarian tissue grafts.

Administration of cyclophosphamide at different stages of follicular maturation in mice: effects on reproductive performance and fetal malformations

This study assessed reproductive performance, fetal viability and teratogenicity in female mice exposed to cyclophosphamide across a timeline corresponding to different stages of follicle maturation. Pregnancies were established in female Balb/c mice 1-4 weeks after administration of a non-sterilizing dose of cyclophosphamide (75 mg/kg). Each mating group represented a different stage of follicular growth at the time of cyclophosphamide exposure. The number of corpora lutea, pregnancies and fetal resorptions were determined. Surviving fetuses were evaluated for gross malformations. Results indicated that conceptions attributable to follicles exposed to cyclophosphamide at a mature stage had a significantly lower number of implantation sites, 4.82 +/- 1.01 versus 8.27 +/- 0.81 in controls (P = 0.001) and a high resorption rate, 56% +/- 0.11 versus 34% +/- 0.07 in controls (P = 0.05). The proportion of corpora lutea in this group which resulted in viable fetuses was extremely low, 0.2 +/- 0.06 versus 0.51 +/- 0.07 in controls (P = 0.001). Malformation rate was more than 10 times higher in all treated groups (P < 0.05) and a particularly high incidence of 33% (P = 0.0014) was observed in conceptions attributable to oocytes exposed to cyclophosphamide at the earliest stages of follicle growth. With an extended interval between exposure and mating the malformation rate gradually decreased towards normal values in the 12th week group. This study suggests that the effect of cyclophosphamide on female gametes and subsequently on future reproduction is influenced by the stage of oocyte maturation at the time of exposure. Early fertilization post-chemotherapy can result in a high rate of pregnancy failure and high malformation rate. This should be taken into account when considering the use of oocyte retrieval, IVF and embryo cryopreservation in patients currently undergoing chemotherapy.

Reproduction post-chemotherapy in young cancer patients

High-dose chemotherapy and radiotherapy has increased long-term survival of young patients with cancer. Sometimes however, the price paid is ovarian failure and sterility. It is highly important to detect who are the patients at risk in order to verify when fertility preservation is indicated. With conventional chemotherapy, there is significant differences in ovarian failure rate according to patients age, disease for which patients are treated for, and the drugs used. Bone marrow transplantation in cancer patients almost invariably induced ovarian failure, irrespective of patient age, treatment protocol or administration of hormonal treatment. Moreover, normal reproductive parameters post-chemotherapy does not necessarily imply that the ovaries escaped damage; ovarian injury is not an all or none phenomenon--partial loss of primordial follicle reserve can result in premature menopause as a delayed reaction to treatment. This should be taken into account while consulting former cancer patients about future planed pregnancies. The direct mechanisms of chemotherapy induced ovarian failure are poorly understood. An in vitro study has demonstrated that in the human ovary chemotherapy acts primarily on primordial follicles through induction of apoptotic changes in pregranulosa cells which lead to follicle loss. Protecting fertility potential in females exposed to chemotherapy with IVF and embryo cryopreservation or cryopreservation of ovarian tissue is practiced. Ovarian tissue cryopreservation: A recent study has demonstrated that laparoscopic ovarian biopsy performed with the round biopter is a safe and efficient method for collecting ovarian tissue for cryopreservation in cancer patients. In order to avoid possible hazards of transferring malignant cells, genetic and immunohistochemical markers for detection of minimal residual cancer cells in ovarian tissue are currently used. However, the reproductive potential of this method is still questionable. IVF: IVF and embryocryopreservation is currently used in infertile patients, however, several obstacles prevent it's wide implementation in cancer patients such as the need for male partner and the time needed for ovarian stimulation. A highly important issue is the possible risk of performing IVF and embryo cryopreservation to preserve fertility in females already exposed to chemotherapy. An animal study has raised serious concerns regarding the consequences of chemotherapy on future pregnancies. High abortion and malformation rates related to the different stages of oocyte maturation at the time of exposure to chemotherapy were demonstrated. These results should be taken into account when considering the use of IVF and embryo cryopreservation following chemotherapy treatment in cancer patients.

Gonadotrophin administration can benefit ovarian tissue grafted to the body wall: implications for human ovarian grafting

Ovarian grafting provides a strategy for clinical infertility treatment and is starting to be used in conjunction with ovarian tissue storage for patients at risk of early ovarian failure. As patients are starting to return for their frozen stored tissue we need to ascertain how to maximise follicle survival when this tissue is grafted back to the patient. For research purposes ovarian tissue is commonly grafted to the kidney capsule as the rich capillary bed at this site favours rapid graft revascularization. This is however not an ideal site for natural conceptions or for the harvest of mature oocytes for in vitro fertilization. While oocytes would be relatively easy to recover from grafts on the abdominal wall or subcutaneous tissue graft revascularization at these sites is slower and evidence indicates that fewer follicles survive. As gonadotropins can upregulate angiogenic growth factors in the ovary this study was designed to test whether the administration of exogenous gonadotropins would increase the number of surviving follicles in grafts placed at less vascularised sites. We showed that exogenous gonadotrophins, given to either the donor or the recipient, could increase the number of developing follicles but the magnitude of this effect was influenced by the timing of the injections relative to the time of grafting.

Hodgkin's Lymphoma

This review focuses on the different treatment options available for the treatment of Hodgkin's disease, with an emphasis on the importance of the long-term sequelae of these therapies.

In Section I, Dr. Linch reviews the current status of Hodgkin's disease treatment. Survival rates have improved over the last three decades due both to better initial therapies and associated supportive care and to the success of salvage therapy. Unlike most other malignancies, a similar survival endpoint can be achieved by different means, e.g., intensive initial therapy resulting in a low relapse rate or less intensive initial therapy and more reliance on salvage therapy. Overall survival has thus become a difficult end-point for clinical trials of primary therapy, and the value of disease-free survival as an end-point can also be questioned. Quality-of-life issues are to the fore of clinical decision and include the psychological trauma of relapse and fertility status. Patient choice is increasingly important. The high level of success in treating Hodgkin's disease also means that attention must be focused on the very long term results and in this context the occurrence of second malignancies is a major issue.

In Section II, Dr. Gosden with Dr. Tulandi and Dr. Tan review the risks of infertility following radio-therapy and chemotherapy and address the actions that can be taken to overcome this problem, particularly for females and prepubertal boys and girls. Particular attention is paid to the recent developments in ovarian cryopreservation and harvesting immature germ cells.

In Section III, Dr. Hancock gives a comprehensive update of the incidence of secondary acute leukemia, non-Hodgkin's lymphoma and solid tumors in a large population of patients treated for Hodgkin's disease. The roles of radiotherapy, chemotherapy and combined modality treatment as risk factors contributing to the development of these secondary malignancies are reviewed. The importance of efforts to prevent late-occurring solid tumors such as lung cancer through smoking cessation programs and early detection by screening for cancers of the breast, thyroid and skin are emphasized.

Hodgkin's Lymphoma

This review focuses on the different treatment options available for the treatment of Hodgkin's disease, with an emphasis on the importance of the long-term sequelae of these therapies.

In Section I, Dr. Linch reviews the current status of Hodgkin's disease treatment. Survival rates have improved over the last three decades due both to better initial therapies and associated supportive care and to the success of salvage therapy. Unlike most other malignancies, a similar survival endpoint can be achieved by different means, e.g., intensive initial therapy resulting in a low relapse rate or less intensive initial therapy and more reliance on salvage therapy. Overall survival has thus become a difficult end-point for clinical trials of primary therapy, and the value of disease-free survival as an end-point can also be questioned. Quality-of-life issues are to the fore of clinical decision and include the psychological trauma of relapse and fertility status. Patient choice is increasingly important. The high level of success in treating Hodgkin's disease also means that attention must be focused on the very long term results and in this context the occurrence of second malignancies is a major issue.

In Section II, Dr. Gosden with Dr. Tulandi and Dr. Tan review the risks of infertility following radio-therapy and chemotherapy and address the actions that can be taken to overcome this problem, particularly for females and prepubertal boys and girls. Particular attention is paid to the recent developments in ovarian cryopreservation and harvesting immature germ cells.

In Section III, Dr. Hancock gives a comprehensive update of the incidence of secondary acute leukemia, non-Hodgkin's lymphoma and solid tumors in a large population of patients treated for Hodgkin's disease. The roles of radiotherapy, chemotherapy and combined modality treatment as risk factors contributing to the development of these secondary malignancies are reviewed. The importance of efforts to prevent late-occurring solid tumors such as lung cancer through smoking cessation programs and early detection by screening for cancers of the breast, thyroid and skin are emphasized.