Testicular function following irradiation of the human prepubertal testis

White paper: Onco-fertility in pediatric patients with Wilms tumor

The survival of childhood Wilms tumor is currently around 90%, with many survivors reaching reproductive age. Chemotherapy and radiotherapy are established risk factors for gonadal damage and are used in both COG and SIOP Wilms tumor treatment protocols. The risk of infertility in Wilms tumor patients is low but increases with intensification of treatment including the use of alkylating agents, whole abdominal radiation or radiotherapy to the pelvis. Both COG and SIOP protocols aim to limit the use of gonadotoxic treatment, but unfortunately this cannot be avoided in all patients. Infertility is considered one of the most important late effects of childhood cancer treatment by patients and their families. Thus, timely discussion of gonadal damage risk and fertility preservation options is important. Additionally, irrespective of the choice for preservation, consultation with a fertility preservation (FP) team is associated with decreased patient and family regret and better quality of life. Current guidelines recommend early discussion of the impact of therapy on potential fertility. Since most patients with Wilms tumors are prepubertal, potential FP methods for this group are still considered experimental. There are no proven methods for FP for prepubertal males (testicular biopsy for cryopreservation is experimental), and there is just a single option for prepubertal females (ovarian tissue cryopreservation), posing both technical and ethical challenges. Identification of genetic markers of susceptibility to gonadotoxic therapy may help to stratify patient risk of gonadal damage and identify patients most likely to benefit from FP methods.

Cancer treatment in childhood and testicular function: the importance of the somatic environment

Testicular function and future fertility may be affected by cancer treatment during childhood. Whilst survival of the germ (stem) cells is critical for ensuring the potential for fertility in these patients, the somatic cell populations also play a crucial role in providing a suitable environment to support germ cell maintenance and subsequent development. Regulation of the spermatogonial germ-stem cell niche involves many signalling pathways with hormonal influence from the hypothalamo-pituitary-gonadal axis. In this review, we describe the somatic cell populations that comprise the testicular germ-stem cell niche in humans and how they may be affected by cancer treatment during childhood. We also discuss the experimental models that may be utilized to manipulate the somatic environment and report the results of studies that investigate the potential role of somatic cells in the protection of the germ cells in the testis from cancer treatment.

Endocrinologic Consequences of Pediatric Posterior Fossa Tumours

Intracranial tumors are the second most frequent malignancies in children and posterior fossa is a common location for these neoplasias during childhood. Recent advances in surgical techniques, radiotherapy and chemotherapy resulted in dramatic increase in the survival rates of these children, however they are still source of a significant morbidity and mortality. Endocrinological complications and late sequelae of childhood posterior fossa tumours are common among the survivors of these tumours and include growth retardation, hypothyroidism, pubertal disorders, gonadal dysfunction and osteopenia. These complications have significant impact on the quality of life of the survivors of childhood posterior fossa tumours. In this paper, the frequency, etiology, and management of these complications will be reviewed.

Late effects of childhood cancer and its treatment

Treatment for childhood cancer with chemotherapy, radiation and/or hematopoietic cell transplant can result in adverse sequelae that may not become evident for many years. A clear understanding of the association between therapeutic exposures and specific long-term complications, and an understanding of the magnitude of the burden of morbidity borne by childhood cancer survivors, has led to the development of guidelines to support lifelong risk-based follow up for this population. It is important to develop interventions to reduce the impact of treatment-related late effects on morbidity and mortality and to continue research regarding the etiopathogenesis of therapy-related cancers and other late effects.

Irradiation causes acute and long-term spermatogonial depletion in cultured and xenotransplanted testicular tissue from juvenile nonhuman primates

Infertility is a serious late effect in childhood cancer survivors. Little is known about acute irradiation effects in immature primate testis. Radiation defects have previously only been studied in postpubertal primates. Here we use the juvenile rhesus monkey as a preclinical model. We expose fragments of testicular tissue to 0, 0.5, 1.0, and 4.0 Gy irradiation in vitro. We then maintain the fragments in organ culture for 24-48 h or xenograft the fragments into nude mice for 4 months. Histological endpoints were determined to explore the cellular responses to the irradiation. At the highest dose, irradiation provoked an acute depletion of A-spermatogonia and a rise of apoptotic germ and Sertoli cells in organ culture. A dose-dependent decrease in the number of seminiferous tubules containing type A dark and type A pale spermatogonia was observed in irradiated xenografts. The number of Sertoli-cell only tubules increased respectively. Outgrowth of grafts was affected by the 4-Gy dose. Our observations reveal that irradiation evoked an immediate and sustained depletion of A-spermatogonia. We conclude that spermatogonia in the juvenile primate testis are highly sensitive to irradiation and that spermatogonial depletion and cessation of proliferation is an acute response. In contrast to adult testes, where such damage is immediately visible, this damage in immature testes becomes apparent only when spermatogonial insufficiency leads to spermatogenic failure, and thus infertility, at the onset of puberty. Our methods are applicable to immature human testis and might serve as powerful tool to study irradiation toxicity in the juvenile human testis.

Endocrine complications of high-dose therapy with stem cell transplantation

Evaluations of endocrine function following hematopoietic cell transplantation demonstrate that the endocrine function abnormalities observed are related to the type of transplant preparative regimen received. Children given high dose cyclophosphamide (CY) only have normal thyroid function, normal growth and development. Children who received a busulfan (BU) plus CY preparative regimen usually have normal thyroid function, normal prepubertal growth, delayed or absent pubertal development, and blunted post-pubertal growth. Recipients of preparative regimens containing total body irradiation may be anticipated to have some thyroid dysfunction, impaired growth rates and delayed or absent pubertal development. Post-pubertal teens and young adults are likely to have gonadal function recover if they received a preparative regimen with CY only but are likely to have primary gonadal failure if they received a preparative regimen with BU or total body irradiation. Individuals whose gonadal function becomes normal have become parents of normal children. All patients who receive a marrow transplant should be followed long-term for development of endocrine function abnormalities.

Follow-up and management of recurrent Wilms' tumor

Over the past 3 decades, enormous advances have been made in the creation of a standardized treatment protocol for Wilms' tumor. Less morbid regimens for low-risk patients and more efficacious aggressive treatment protocols for high-risk patients have been developed, and continue to be improved with newer studies, such as the NWTS-V. An area that has posed a more challenging aspect of the disease is its relapse. Although a standard follow-up protocol has been produced by in-depth evaluation of previous works, there has been a great deal of difficulty demonstrating improved relapse-free and overall survival rates in re-treatment of children suffering from recurrent Wilms' tumor. Several factors are involved in the success of treatment of relapse, some of which include prerelapse treatment of initial disease and stage, site, and timing of recurrence. New agents and their combination with chemotherapeutics that already have established efficacy are being used for treatment of Wilms' tumor relapse, with varying success. These studies should lead the way for newer investigations in the future. Patients with anaplastic disease, rhabdoid tumors, and clear cell sarcoma are especially in need of these future investigations. Perhaps the true final frontier is establishing the likelihood of patients suffering a relapse. This topic currently is being studied in the fields of biologic markers and gene expression. This knowledge will hopefully, in turn, tailor initial treatment in a more specific manner.

[Radiation reactions in the gonads: importance in patient counseling]

PURPOSE

The intention of this article is to summarize the effects of radiation therapy on the female and male gonadal function.

RESULTS

In woman a decreasing tolerance to radiation is observed with increasing age, due to the decreasing number of follicles. The mean tolerance dose for sterilization is between 5 and 10 Gy. If both ovaries receive only scattered doses-radiation effects on the ovaries are dependent on the age of the women at the time of treatment. However, if both ovaries are included in the treatment volume of a tumor radiation therapy, sterilisation is unavoidable. In man even scattered doses are able to decrease the sperm cell counts in the range of 2 to 3 Gy in conventional fractionation regimes. Complete restoration of spermatogenesis is possible during the first 2 years after treatment, but is unlikely after 3 years. In contrast to the situation in female, impairment of male endocrine gonadal functions are observed only after testicular doses higher than 20 to 30 Gy. In female children the tolerance dose of the ovaries is higher than in the adult woman, while the gonadal endocrine function in boys is more sensitive than in adult men. In contrast, spermatogenesis is not initiated in young boys, and hence less radiation effects are induced.

CONCLUSIONS

In all treatment situations-in adults as well as in children-an additive effect of the combination of chemotherapy with radiation on gonadal function has been shown. However, the severity of damage by radio-chemotherapy is highly dependent on the drugs used.

Gonadal function after bone marrow transplantation for acute leukemia during childhood

OBJECTIVE

To examine the impact of bone marrow transplantation (BMT), using high-dose chemotherapy and hyperfractionated total body irradiation, on gonadal function in survivors of acute leukemia treated during childhood.

STUDY DESIGN

We conducted a retrospective study of 33 subjects (17 boys) who underwent a BMT for acute leukemia (acute lymphoblastic leukemia, n = 20; acute myelogenous leukemia, n = 13) at a single institution. All patients were prepubertal at the time of BMT (median age, 7.1 years (3.7 to 11.6 years)); at the time of their last examination the boys were a median of 14 years (10.4 to 17.1 years) of age and the girls were a median of 16.9 years (9.5 to 21.9 years) of age.

RESULTS

Of 17 boys, 14 (82%) entered puberty spontaneously and 13 demonstrated age-appropriate plasma concentrations of testosterone. Two boys (aged 10.5 and 11 years) remain clinically and hormonally prepubertal, and one boy has overt Leydig cell failure requiring androgen replacement therapy. Thirty-six percent of pubertal boys have elevated plasma concentrations of luteinizing hormone and 64% have raised levels of follicle-stimulating hormone. Boys with increased levels of luteinizing hormone were significantly younger at BMT (5.4 +/- 0.8 vs 7.8 +/- 0.8 years; p = 0.024). Of 16 girls, 9 (56%) had spontaneous puberty with onset of menarche at a median age of 13 years (9.5 to 15.8 years). Though six (67%) of these nine girls have had increased plasma concentrations of luteinizing and follicle-stimulating hormones, normalization has occurred in two during a period of 4 to 7 years. The remaining seven subjects required hormone replacement because of clinical and biochemical evidence of ovarian failure. One of these subjects has recovered ovarian function after 5 1/2 years. Female patients with ovarian failure were significantly older at BMT compared with female patients with spontaneous puberty/menarche (8.6 +/- 23 years vs 6.1 +/- 1.8; p = 0.03).

CONCLUSION

Our results indicate that most prepubertal boys undergoing BMT with chemotherapy and hyperfractionated total body irradiation can expect to enter and progress normally through puberty. For prepubertal girls treated with these regimens, at least 50% retain adequate ovarian function to enter puberty and menstruate regularly.

The effects of irradiation and chemotherapy on growth

The effects of cancer therapy on growth are reviewed. The effects of radiation and chemotherapy on growth hormone production and growth hormone responsiveness by peripheral tissues are examined. The effects of radiotherapy and chemotherapy on other endocrine function pertaining to growth also are discussed. An approach to surveillance of pediatric cancer survivors pertaining to growth and development is suggested.

Mechanism and management of treatment-related gonadal failure in recipients of high dose chemoradiotherapy

For the last two decades, the use of bone marrow transplantation for leukaemia, and most recently for lymphomas and other cancers, has increased dramatically and all of the systemic chemotherapy or radiotherapy used in these patients has a potential for causing infertility. This review describes the normal reproductive function of relevance to patients at risk of chemotherapy- or radiotherapy-induced infertility. The mechanism by which fertility may be affected by these agents is also described and therapeutic strategies for reducing or preventing these problems are outlined. The treatment of men and women who are infertile after chemotherapy or radiotherapy is addressed, as are the ethical and legal aspects of assisted fertilization.

Pubertal growth in response to testosterone replacement therapy for radiation-induced Leydig cell failure

The adolescent growth pattern of eight boys, who had puberty induced with androgen replacement therapy following radiation-induced Leydig cell failure, was studied from induction of puberty at a mean age of 13.1 years (range 11.6-14.5) to final height at mean age of 18.8 years (range 17.7-20.3). The mean gains during puberty (SD) for standing height, sitting height, and sub-ischial leg length were 18.56 cm (3.98), 10.46 cm (2.39), and 8.1 cm (2.01) respectively, which were significantly reduced compared with normal Tanner standards (P < .001). The peak velocity for each parameter occurred in the 1st year of induced puberty in contrast to the pattern in normal adolescence, although the mean peak velocity for each auxological parameter was not significantly different from the normal Tanner standards. The mean adult standing height (SD), 167.5 cm (9.88), and mean adult leg length (SD), 80.8 cm (6.19), were not significantly different from the normal Tanner standards, whereas the mean adult sitting height (SD), 86.7 cm (4.78), was shorter (P < .001). Three of the eight patients had a leg length standard deviation score less sitting height standard deviation score in excess of +2.96 suggesting the presence of significant skeletal disproportion. Seven of the eight boys reached target genetic height, though in six, the final height was below mid-parental height (P < .05). The modest loss in height potential was mainly due to radiation-induced skeletal dysplasia attenuating the growth of the spine. The families of boys with radiation-induced Leydig cell failure requiring androgen replacement therapy can be reasonably optimistic about height prognosis as seven of the eight boys reached target genetic height.

The survivors of childhood solid tumors

With the improvement in cancer therapy in recent years, the number of cancer survivors is rapidly increasing. Potential late medical and psychosocial sequelae of cancer therapy are reviewed. A practical guide for the primary health care giver is provided.

Effects of gonadotropin-releasing hormone analogs on cis-platinum-induced spermatogenic damage

In order to test the hypothesis that pretreatment with gonadotropin-releasing hormone (GnRH) analogs might ameliorate cytotoxic drug-induced testicular damage, mature male Wistar rats were pretreated for 2 weeks with a GnRH superactive agonist or a pure GnRH antagonist prior to, and for 1 week after, a 5 mg/kg intraperitoneal dose of cis-platinum. Despite inhibition of testicular function by both GnRH analogs prior to cis-platinum administration, there was no evidence of protection or enhanced recovery of spermatogenesis at 6 and 12 weeks after cis-platinum treatment, and spermatogenesis was significantly further depressed at both time-points by both GnRH agonist and antagonist pretreatment. This suggests that pretreatment with GnRH analogs in the rat does not protect spermatogenesis from cis-platinum-induced testicular damage within up to two spermatogenic cycles and that hypogonadism at the time of cytotoxic drug treatments may aggravate testicular damage.

Male reproductive function in long-term survivors of childhood cancer

We evaluated reproductive function in 27 male long-term survivors of childhood cancer treated during the prepubertal and pubertal period. Sperm samples were obtained from 23 patients; four who refused to provide specimens indicated that they had fathered normal healthy children. Thirteen patients were 12 years old or younger at the time of diagnosis and initiation of therapy. Chemotherapy was calculated according to the cumulative amount of drug administered and correlated with the surface area. Sterility was associated with large doses of single alkylating agents or reduced doses administered with other agents in combination regimens. It was noted in boys treated in both the prepubertal and pubertal period. Sterility was also observed in patients who received testicular radiation alone or in combination with chemotherapy. However, it was not an inevitable consequence in all patients, despite treatment with similar or identical regimens. Fertility potential could not be predicted by clinical examination (testicular size) or gonadotrophin and testosterone values. The results were compared to published reports of treatment-induced sterility in adult males. Additional investigations are required to establish more accurate correlations of dosage with reproductive potential.

Prepubertal endocrine follow-up in subjects with Wilms' tumor

Twenty-three prepubertal subjects treated for Wilms' tumor (10 males and 13 females) were endocrinologically evaluated off therapy from 0.5 to 4.08 years. They were divided into two groups: 11 subjects (6M, 5F) who had received chemotherapy only (group 1) and 12 (4M, 8F) who had in addition received abdominal radiation (1,500-3,000 rads) (group 2). Follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), thyroid-stimulating hormone (TSH), free thyroxine (FT4), free tri-iodo thyronine (FT3), testosterone (T), estradiol-17 beta (E2), and cortisol (F) were measured by radioimmunoassay (RIA). Plasma levels of TSH, PRL, FT4, FT3, and F were normal in both groups, as were FSH, LH, T, and E2 in group 1. In group 2, female subjects showed FSH levels significantly higher than controls, while LH and E2 were normal; male subjects showed significantly higher LH levels, while FSH and T levels were normal. These results indicate that in the treatment protocol used by us for Wilms' tumor (WT), chemotherapy does not affect endocrine function, whereas abdominal radiation seems to damage gonadal function directly. The present findings indicate that gonadal damage may be revealed in WT before puberty not only in females, as has been previously reported, but also in male subjects.

The effect of total body irradiation and bone marrow transplantation during childhood and adolescence on growth and endocrine function

Seventeen children (11 M, 6 F) with acute leukaemia and myeloproliferative disorders were investigated for growth and endocrine dysfunction. All had undergone bone marrow transplantation prepared with cyclophosphamide and single fraction total body irradiation (900-1000 cGy) between 1.5 and 3.8 (mean 2.2) years previously. The majority of children exhibited growth failure, which was of multiple aetiology. Ten patients, of whom eight had had previous prophylactic cranial irradiation, had evidence of growth hormone deficiency based on the reduced growth hormone response to insulin induced hypoglycaemia. Three patients had evidence of hypothalamic damage as shown by their growth hormone response to 200 micrograms GHRH (1-29) NH2 intravenously. Gonadal failure was common, assessed clinically, and biochemically by basal gonadotrophin and sex steroid concentrations. All four girls of adolescent age (10.6-14.1 years) had ovarian failure requiring sex steroid replacement. Of the eight boys of adolescent age (12.3-18.3 years), two had testicular failure requiring sex steroid supplements. Both of these had had previous testicular irradiation. Five others had compensated gonadal failure, and one had normal Leydig cell function. Abnormalities of the TSH response to TRH occurred in 10 patients but only three had overt hypothyroidism. Unlike growth hormone deficiency, gonadal and thyroid dysfunction showed no correlation with previous cranial radiotherapy.

Isolated testicular leukemic relapse. Response to radiation therapy

Between January, 1975, and December, 1984, at the University of Michigan Medical Center, 17 boys with leukemia presented with overt or occult isolated testicular relapse. Diagnosis was obtained by bilateral open-wedge biopsies of the testes. All the patients were treated with combined local testicular irradiation and systemic chemotherapy. In only 1 of the 17 patients (6%) testicular leukemia developed as the only site of relapse. It appears that doses in the range of 2,000 to 2,400 cGy in 10 to 12 fractions achieve optimum control of leukemic infiltration of the testes.

Leydig cell damage after testicular irradiation for lymphoblastic leukaemia

The effect of testicular irradiation on Leydig cell function has been studied in a group of boys irradiated between 1 and 5 years earlier for a testicular relapse of acute lymphoblastic leukaemia. Six of the seven boys irradiated during prepubertal life had an absent testosterone response to HCG stimulation. Two of the four boys irradiated during puberty had an appropriate basal testosterone level, but the testosterone response to HCG stimulation was subnormal in three of the four. Abnormalities in gonadotrophin secretion consistent with testicular damage were noted in nine of the 11 boys. Evidence of severe Leydig cell damage was present irrespective of whether the boys were studied within 1 year or between 3 and 5 years after irradiation, suggesting that recovery is unlikely. Androgen replacement therapy has been started in four boys and will be required by the majority of the remainder to undergo normal pubertal development.

Hypothalamo-hypophyseal-testicular function in prepubertal boys with acute lymphoblastic leukemia following chemotherapy and testicular radiotherapy

Hypothalamo-hypophyseal-testicular function was studied in twenty-eight prepubertal boys with ALL in clinical and haematological remission. Eighteen were treated with combined systemic chemotherapy (24-36 months) and the other ten, who had testicular leukemic infiltrates, received chemotherapy (38-60 months) and testicular radiotherapy (2 000 rad). Plasma levels of LH and FSH were measured before and after stimulation with LHRH (100 micrograms i.v.) and plasma levels of testosterone before and after stimulation with hCG (1 500 IU/48 h/7 doses). In patients treated with chemotherapy alone, mean basal LH and FSH, mean responses to LHRH stimulation and mean testosterone levels after stimulation with hCG did not significantly differ from those of the controls. Five of these patients who had normal testosterone values after three doses of hCG had testosterone values below the normal range after seven doses. In patients treated with chemotherapy and testicular radiotherapy, mean basal FSH and mean responses to LHRH stimulation were significantly higher than those of the controls. Testosterone values after stimulation with hCG were low in three and very low in the other seven. In both groups of patients data from testicular biopsies were consistent with functional results. We conclude that chemotherapy causes slight testicular damage, but chemotherapy and testicular radiotherapy produce severe testicular damage in patients with testicular leukemic infiltrates.

Testicular function following bone marrow transplantation performed during or after puberty

Testicular function was assessed in eight males who had undergone bone marrow transplantation (BMT) during or shortly after puberty. Their ages ranged between 10 years, 10 months and 17 years, 3 months (median, 13 years, 7 months) at the time of BMT, and they were followed 13 to 77 months (median, 36 months) posttransplantation. Therapy for BMT consisted of high-dose, short-term chemotherapy either alone (Group I) or in combination with single-dose irradiation, total lymphoid (Group II) or total body (Group III). Subjects in Group III had all received combination chemotherapy prior to BMT. Hormonal and clinical evidence of germ-cell dysfunction was common in that 6 patients manifested elevated plasma levels of follicle-stimulating hormone (FSH), and four subjects were found to have a subnormal testicular volume. Of the six patients with abnormal FSH values, four were followed serially, and all showed normalization over time. Leydig cell function was less impaired in that seven of the eight patients produced normal adult male levels of testosterone, including three subjects with elevated luteinizing hormone (LH) levels. All eight developed normal adult male secondary sexual characteristics. It is concluded that the therapy utilized for BMT causes damage primarily to germinal epithelium which appears amenable to recovery. This may be due, in part, to the use of single dose rather than fractionated radiation.

Testicular infiltrates in children with acute lymphoblastic leukemia: a prospective study

The incidence of testicular infiltrates in 68 boys with acute lymphoblastic leukemia in first remission (1974-81), was prospectively investigated through careful clinical examination and routine bilateral biopsies at 2-3 years of remission. All boys were under 14 years of age and they were treated with protocols D.74 and Pethema 7/78. Seven patients (10.3%) presented an isolated testicular relapse (ITR) during the chemotherapy period. In 13 of the 43 testicular biopsies (31%) leukemic infiltrates were found, and in another two findings were controversial. Three boys, two with previous negative biopsies, had an ITR 6 to 18 months after therapy was stopped. Finally, three others had simultaneous relapses in testes and bone marrow, one during chemotherapy and two after suppression. In all, 23 patients (33.8%) in first remission had overt or occult ITR. Overall estimated incidence rate of testes leukemia is 40% in all the groups. Incidence of early and occult ITR was higher in boys with initial WBC counts over 20 X 10(9)/1. Therapy in ITR generally consisted of local radiotherapy (20-25 Gy), a new induction treatment followed by 2-year maintenance treatment; in three patients with early ITR, orchidectomy was also performed and six were given a new CNS preventive treatment. Clinical course in the seven patients with early ITR was unfavourable in five, with subsequent hematological relapses and death; one had a long-term disease-free survival (80 + months) and the other was a recent case. Ten of the 13 patients with occult infiltrates continued in remission and four were off treatment with a follow-up of over 66 months. The three patients with late ITR were in 2nd remission at 8-18 months after a new cessation of therapy. It may be concluded from this study that prognosis in ITR is related to the phase of presentation: it is unfavourable in cases of early ITR, but in occult infiltrates, detected by routine biopsy, and in late ITR combined therapy is effective in most cases.

The effect of testicular irradiation on Leydig cell function in prepubertal boys with acute lymphoblastic leukaemia

Testicular function was investigated by the luteinising hormone releasing hormone (LHRH) test and a three day human chorionic gonadotrophin (HCG) test in 11 prepubertal boys with acute lymphoblastic leukaemia (ALL) who had received 2400 rads of fractionated radiation to their testes after relapse at this site. The results were compared with an unirradiated control group. Basal and peak testosterone values after 1000 units of HCG were significantly lower in the irradiated patients than in the control group. Peak follicle stimulating hormone (FSH) values after 100 micrograms LHRH were significantly higher in irradiated boys, but there was no difference in either basal FSH or basal and peak luteinising hormone values. The findings suggest that the ability of the Leydig cell to produce testosterone--as detected by the HCG test--is appreciably reduced after irradiation and that tubular dysfunction in prepubertal boys may sometimes be predicted by a raised FSH response.

Growth and endocrine function after treatment for medulloblastoma

Children with medulloblastoma in Bristol are treated surgically and with craniospinal irradiation, and in some cases chemotherapy. Thirteen medium or long term survivors were investigated to determine their growth and endocrine function. Their rate of growth was considerably reduced through the first year of their illness and after spinal irradiation spinal growth was poor. Nine children developed growth hormone deficiency. They were clinically euthyroid but 7 had raised basal thyroid stimulating hormone values. Gonadal function was abnormal in all but the youngest child. The rate of survival is increasing in children with medulloblastoma but this is associated with appreciable endocrine abnormalities. Some of these problems are present shortly after treatment ends but others may develop later and long term surveillance is therefore essential.

Leydig-cell function in children after direct testicular irradiation for acute lymphoblastic leukemia

To assess the effect of testicular irradiation on testicular endocrine function, we studied 12 boys with acute lymphoblastic leukemia who had been treated with direct testicular irradiation 10 months to 8 1/2 years earlier. Insufficient Leydig-cell function, manifested by a low response of plasma testosterone to chorionic gonadotropin or an increased basal level of plasma luteinizing hormone (or both), was observed in 10 patients, 7 of whom were pubertal. Two of these patients had a compensated testicular endocrine insufficiency with only high plasma concentrations of luteinizing hormone. Testosterone secretion was severely impaired in three pubertal boys studied more than four years after testicular irradiation. A diminished testicular volume indicating tubular atrophy was found in all pubertal patients, including three who had not received cyclophosphamide or cytarabine. These data indicate that testosterone insufficiency is a frequent complication of testicular irradiation, although some patients continue to have Leydig-cell activity for several years after therapy.

Gonadal function after combination chemotherapy for Hodgkin's disease in childhood

The effect of quadruple chemotherapy (mustine, vincristine, procarbazine, and prednisolone) on gonadal function was investigated in 15 males and 2 females treated for Hodgkin's disease during childhood. The 2 females have regular menstrual cycles with evidence of ovulation in one. Twelve of the males have shown normal progression of pubertal development since completing their treatment. Nine out of 10 late pubertal or adult subjects had small testes but only one developed gynaecomastia. All 4 prepubertal subjects had normal basal and peak gonadotrophin responses to luteinising hormone-releasing hormone. Nine of the 12 subjects studied during puberty or adulthood had either an increased basal serum follicle-stimulating hormone (FSH) level or an exaggerated FSH response to luteinising hormone-releasing hormone. Each of the 6 males who provided semen for analysis was azoospermic after an interval of between 2.4 and 8 (mean 5.3) years after completion of treatment. We conclude that severe testicular damage is common after treatment with mustine, vincristine, procarbazine, and prednisolone in childhood. The germinal epithelium is particularly vulnerable and the resultant azoospermia is likely to be irreversible. The Leydig cells are less susceptible to cytotoxic-induced damage. Pubertal development is normal and there is no indication for androgen replacement therapy.

Pubertal development in children treated for nephroblastoma

Recent improvements in the treatment of children with nephroblastoma have led to an increase in the disease-free survival rate. The late effect of treatment on long-term survivors requires assessment to determine whether avoidable iatrogenic disorders are appearing. The onset of puberty is one measurement of physical development and has been used in the study to assess the progress of 16 children over the age of 12 yr who were treated for nephroblastoma. The method consisted of the measuring body height, weight and testicular size, estimating serum levels of luteinizing hormone, follicular stimulating hormone and testosterone, recording the age at menarche, and staging of pubic hair and breast development. There was evidence of complete ovarian suppression in 3 out of 10 girls and of delayed and testicular function in 1 out of 6 boys. Analysis of the treatment received by the children implicated radiotherapy as the responsible factor causing gonadal suppression.

Testicular function after combination chemotherapy in childhood for acute lymphoblastic leukaemia

We have assessed testicular function with luteinising hormone-releasing hormone (LH-RH) and human chorionic gonadotrophin stimulation tests in 44 boys previously treated with, or currently receiving, chemotherapy for acute lymphoblastic leukaemia (ALL). At the same time a testicular biopsy was performed in each boy and the morphology was studied. Histologically the chemotherapy appeared to damage the tubular system in particular, and the degree of damage was assessed by estimating the tubular fertility (TF) index which is defined as the percentage of seminiferous tubules containing identifiable spermatogonia. The mean TF index in all 44 biopsies was 51%. Only 2 of the 44 boys showed an absent or blunted testosterone response to human chorionic gonadotrophin. This suggests that Leydig cell function is rarely impaired by such chemotherapy and that most of the boys, similarly treat for ALL, will undergo normal pubertal maturation. Apart from the basal luteinising hormone (LH) levels in the prepubertal group which could not be compared, the median basal serum follicle-stimulating hormone (FSH), LH, and testosterone concentrations, the median peak FSH and LH responses to LH-RH, and the mean plasma testosterone responses to human chorionic gonadotrophin stimulation did not differ between the prepubertal, early pubertal, and late pubertal groups compared with normal boys of similar pubertal maturation. Three of 32 prepubertal ALL boys, and 5 of 12 pubertal ALL boys showed abnormalities of gonadotrophin secretion. The increased frequency of abnormalities of FSH secretion in the pubertal ALL boys compared with the prepubertal ALL boys could not be explained by more severe tubular damage in the former group. We conclude that moderately severe damage to the tubular system of the testis unassociated with Leydig cell impairment may not be detected in the prepubertal boy with current tests of testicular function.