Endocrine late effects of cancer treatment

NORMAL TISSUE REACTIONS TO CHRONIC RADIATION EXPOSURE IN MAN

This paper presents an overview of radiobiological dependences governing the occurrence of tissue (organ) reactions that determine the outcomes of chronic exposure to low-LET ionizing radiation (IR) in humans. The mechanisms involved in the development of tissue reactions (TRs) to long-term exposures to IR and radioadaptation are considered. The overview describes the reactions of the haematopoietic, immune, nervous, reproductive and endocrine systems, lungs, skin and crystalline lens to chronic radiation exposure, which are of fundamental importance in view of radiation protection. It is shown that the individual's physiological tissue (organ) reserve, and also that induced by radiation exposure at low-dose rates are of great significance in the context of TR development.

Recruitment feasibility to a cohort study of endocrine and metabolic health among survivors of childhood brain tumours: a report from the Canadian study of Determinants of Endometabolic Health in ChIlDrEn (CanDECIDE)

OBJECTIVES

The aim of this study was to test the feasibility of recruitment and performance of study procedures of the Canadian Study of Determinants of Endometabolic Health in ChIlDrEn (CanDECIDE) study, which was designed to assess the determinants of endocrine and metabolic health in survivors of childhood brain tumours.

SETTING

A single paediatric tertiary care centre in Hamilton, Ontario, Canada.

PARTICIPANTS

We included boys and girls, aged 5 years and older, who were lean (body mass index (BMI) below 85th centile for age and gender) or overweight/obese (BMI 85th centile or above for age and gender). We excluded children on steroids or immunosuppressant therapy, smokers and those who had an active infection for the 2 weeks prior to participation.

OUTCOMES

Feasibility targets included recruitment rate of at least 50%, the consenting of 80% of participants to provide biological samples, 90% questionnaire completion rate and the ability to process biological samples from at least 80% of participants.

RESULTS

We approached 210 potential participants, and of the 112 (53%) who agreed to participate, 30 (26.8%) completed the study visit over 7 months. All participants agreed to fast, provide biological samples and complete the questionnaires. Sample collection was successful in 97% (29/30) of participants and laboratory procedures were feasible in 100% of collected samples. We also tested resources required for the conduct of the full study including personnel, space, laboratory equipment and procedures and determined that they are all feasible.

CONCLUSIONS

Recruitment and consenting of patients for the CanDECIDE study may be feasible. However, we are considering prolonging recruitment duration and collaboration with other centres to meet recruitment targets due to lower than expected recruitment rate. Completion of questionnaires and implementation of sample processing protocols are feasible.

Canadian Study of Determinants of Endometabolic Health in ChIlDrEn (CanDECIDE study): a cohort study protocol examining the mechanisms of obesity in survivors of childhood brain tumours

BACKGROUND

Childhood obesity has reached epidemic proportions and is impacting children's health globally. In adults, obesity is associated with chronic low-grade inflammation that leads to insulin resistance, which is one of the important mechanisms through which dysregulation of metabolism occurs. There is limited information available about the contribution of inflammation to metabolic health in obese children, and how individual and lifestyle factors impact this risk. One of the paediatric groups at risk of higher rates of obesity includes the survivors of childhood brain tumours. The aim of this study was to evaluate the mechanisms that contribute to inflammation in obese survivors of childhood brain tumours.

METHODS AND ANALYSIS

This is a prospective cohort study. We will recruit lean and obese survivors of childhood brain tumours, and a control group composed of lean and obese children with no history of tumours. We will measure circulating and urinary cytokine levels and cytokine gene expression in monocytes. In addition, the methylation patterns of cytokine genes and that of toll-like receptor genes will be evaluated. These will be correlated with individual and lifestyle factors including age, sex, ethnicity, puberty, body mass index, fasting lipid levels, insulin sensitivity, diet, exercise, sleep, stress and built environment. The sample size calculation showed that we need 25 participants per arm

ETHICS AND DISSEMINATION

This study has received ethics approval from the institutional review board. Once completed, we will publish this work in peer-reviewed journals and share the findings in presentations and posters in meetings.

DISCUSSION

This study will permit the interrogation of inflammation as a contributor to obesity and its complications in obese survivors of childhood brain tumours and compare them with lean survivors and lean and obese controls with no history of tumours, which may help identify therapeutic and preventative interventions to combat the rising tide of obesity.

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

A cross-sectional study of overweight in pediatric survivors of acute lymphoblastic leukemia (ALL)

BACKGROUND

Survivors of childhood acute lymphoblastic leukemia (ALL) are at risk for overweight, predisposing them to long-term morbidity. We examined the relationship between body mass index (BMI) and demographic and lifestyle factors in a cohort of ALL survivors.

PROCEDURE

We enrolled consecutive ALL survivors who attended the institutional AfterCare Clinic over a 1-year period. BMI (kg/m(2) ) at diagnosis, end-therapy, and current time were calculated. Survivors were classified as overweight/obese (overweight group; BMI for age ≥ 85th percentile) or normal/underweight (normal weight group; BMI for age <85th percentile). We assessed the relationship between current BMI and self-reported current caloric intake, physical activity, and sedentary behavior.

RESULTS

102/157 (65%) eligible survivors consented to enrollment. Median age was 14.3 years (range 8.4-18.6) and time from end of treatment 7 years (2.5-15.6). The proportion of overweight survivors was 21%, 45%, and 35% at diagnosis, end-therapy, and current time, respectively. The overweight group reported less calories (Δ324 kcal, P = 0.018), fat (Δ14.5 g, P = 0.02), and carbohydrates (Δ39 g, P = 0.02) than the normal weight group. These differences disappeared after excluding patients classified as under-reporting their calorie intake according to the Goldberg cut-off method. There were no differences in sedentary behavior or activity between groups.

CONCLUSIONS

Many children with ALL gain weight during therapy and fail to return to normal weight after treatment concludes. Subsequent diet, physical activity, and sedentary behavior do not appear to differ between overweight and normal weight survivors. Clinicians should focus on ways to minimize weight gain during therapy rather than waiting for treatment to conclude.

Time-dependent alterations in growth and bone health parameters evaluated at different posttreatment periods in pediatric oncology patients

Bone mineral density (BMD) and anthropometric measurements in pediatric cancer patients were evaluated and compared at early and late posttreatment periods. Sixty-six pediatric cancer patients who recovered completely following treatment longer than at least a 6-month period were included in the study. Patients were evaluated cross-sectionally and prospectively with regard to anthropometric measurements and BMD twice; the first being at a mean period of 2.62 ± 1.44 years and the second of 6.55 ± 1.71 years after the completion of treatment. Rates of osteoporosis and osteopenia at first or second evaluation were 25.8% and 39.4% or 10.6% and 19.7%, respectively. Mean BMD z-scores were (-1.26) ± 1.12 [(-4.3)-2.0] and (-0.48) ± 1.25 [(-3.30)-3.40] at first and second evaluations, respectively. BMD findings obtained at second evaluation revealed statistically significant recovery compared with those obtained at first evaluation (P = .001). BMD z-scores were significantly lower in patients who received, as opposed to those who did not receive, radiotherapy (RT) at both evaluations. Anthropometric parameters of patients such as height, weight, and body mass index (BMI) were increased at both evaluations compared with values obtained at diagnosis (P < .05). Height standard deviation score (SDS) decreased at first evaluation compared with that measured at diagnosis, whereas it increased at second evaluation. Conversely, weight SDS and BMI SDS increased (P < .05) at first evaluation compared with that measured at diagnosis, whereas they decreased at second evaluation. The authors conclude that early impairments in anthropometric measurements recover in the long term, whereas BMD is continually reduced in children who recovered from cancer.

Adverse effects of treatment in childhood acute lymphoblastic leukemia: general overview and implications for long-term cardiac health

Survival of childhood acute lymphoblastic leukemia (ALL) is one of the greatest medical success stories of the last four decades. Unfortunately, childhood ALL survivors experience medical late effects that increase their risk of morbidity and premature death, often due to heart and vascular disease. Research has helped elucidate the mechanisms and trajectory of direct damage to the heart from treatment exposure, particularly to anthracyclines, and has also contributed knowledge on the influences of related chronic conditions, such as obesity and insulin resistance on heart health in these survivors. This article summarizes the key issues associated with early morbidity and mortality from cardiac-related disease in childhood ALL survivors and suggests directions for interventions to improve long-term outcomes.

Gonadal Function in Patients Treated for Leukemia in Childhood

Ovarian and testicular function were assessed in 67 long-term survivors (37 females, 30 males) treated for leukemia between 1973 and 1992. At diagnosis they were 1-16 (median 5) years old and had evaluation of gonadal function 4-25 (median 13) years later at the age of 13-31 (median 19). All had been treated with various combinations of chemotherapy (ChT) (including cyclophosphamide (CYC) and cytarabine in 32 patients), 62 patients had received prophylactic cranial irradiation with 12-49 (median 18) Gy, 2 patients had had craniospinal irradiation with 24 and 10 Gy respectively. Nine patients were treated for relapse; 2 boys had testicular irradiation (RT) with 12 Gy in 3 fractions and 1 girl whole-abdomen RT with 20 Gy as a part of this treatment. Three patients were treated for second malignancies. Gonadal function was assessed by clinical examination and measurement of serum concentrations of estradiol and testosterone. Serum levels of LH and FSH were determined in basal state and after stimulation. Primary hypogonadism was found in 6 (9%) patients. Five (16,5%) males had primary hypogonadism with evidence of damage to the germinal epithelium, 2 of them, treated with testicular RT, had evidence of damage to the Leydig cells and 2 had evidence of dysfunction of Leydig cells as well. Primary hypogonadism was found in 1 female, who was heavily treated for relapse (ChT containing CYC, abdominal RT and craniospinal RT). She was amenorrhoic and needed substitutional estrogen therapy but delivered a child anyway. Five females had early puberty after cranial RT. One female had secondary hypogonadism and hyposomatotropism after cranial RT with 30 Gy, one male had hyposomatotropism after receiving cranial RT twice (49 Gy total). Primary treatment for leukemia does not produce primary hypogonadism in girls, but it does in boys. Alkylating agents and gonadal RT are the most damaging factors. Not only RT to gonads but also alkylating agents alone cause dysfunction of Leydig cells.

Adverse Late Effects of Childhood Cancer and Its Treatment on Health and Performance

More than 12,000 newly diagnosed cases of cancer occur each year in the United States among children ages 20 years or younger, and the current 5-year survival rate is near 80%. An estimated 228,000 among adults 47 years or younger and currently living in the United States had a diagnosis of cancer during childhood or adolescence. Here, we review long-term adverse effects of childhood cancer and its treatment with an emphasis on physical performance and health. We also briefly review existing guidelines that may be used to develop appropriate exercise and diet interventions for childhood cancer survivors. We suggest that there is a need for development of evidence-based, risk-based guidelines and interventions for health promotion among long-term childhood cancer survivors, particularly for those whose physical activity limitations interfere with chances for optimizing their bodies' potential in today's society.

The prevalence of overweight and obesity in pediatric survivors of cancer

OBJECTIVE

To compare the prevalence of overweight in a cohort of pediatric survivors of cancer with that in the general population.

STUDY DESIGN

We reviewed the charts of 441 cancer survivors followed at a Canadian tertiary care pediatric hospital and calculated their most recent body mass index. We compared this cohort with population data generated from the Canadian Community Health Survey.

RESULTS

At a median age of 14.7 years (range, 3.4 to 19.5 years) and a median time from diagnosis of 9.7 years (range, 3.4 to 19.2 years), 140 of 441 patients (31.7%) were overweight or obese. Only 12 of the 441 patients (2.7%) were underweight. Males age 6 to 11 years (odds ratio [OR] = 2.29; 95% confidence interval [CI] = 1.36 to 3.86; P < .001) and male survivors of acute lymphoblastic leukemia (OR = 1.55; 95% CI = 1.03 to 2.52; P = .04) were more likely to be overweight than the general population. No other age or diagnostic group had an increased risk of overweight.

CONCLUSIONS

The prevalence of overweight was not increased in this cohort compared with the general population. However, almost 1/3 of these patients are overweight, necessitating a clinical and research focus on preventing and combating overweight in childhood cancer survivors.

Metabolic syndrome and growth hormone deficiency in adult survivors of childhood acute lymphoblastic leukemia

BACKGROUND

The purpose of the study was to determine the prevalence of metabolic syndrome, growth hormone deficiency, and cardiovascular risk factors among adult survivors of childhood acute lymphoblastic leukemia (ALL) treated with or without cranial irradiation.

METHODS

Follow-up was undertaken of 75 randomly selected long-term childhood ALL survivors. Testing included fasting insulin, glucose, lipids, and growth hormone (GH) releasing hormone plus arginine stimulation test. The prevalence of metabolic syndrome was compared with population norms from 1999-2002 National Health and Nutrition Examination Study (NHANES) data, and internally between those with and without past cranial irradiation and those with normal (>16.5 microg/L) versus insufficient (9-16.5 microg/L) versus deficient (<9 microg/L) peak GH secretion.

RESULTS

The mean subject age was 30 years and the mean time since ALL diagnosis was 25 years. The prevalence of metabolic syndrome did not differ statistically (P = .87) between study subjects (16.6%) and same-age, same-sex population norms (17.5%). However, 60% of subjects treated with cranial irradiation, compared with 20% of those who were not, had 2 or more of the 5 components of metabolic syndrome. Untreated abnormally low GH was present in 64% of subjects overall and 85% of those who received past cranial irradiation. Cranial irradiation was strongly related to GH deficiency, and in turn lower insulin-like growth factor 1 (IGF-1), higher fasting insulin, abdominal obesity, and dyslipidemia, particularly in women.

CONCLUSIONS

Hematologists who treat childhood ALL patients, and particularly those who provide primary care to adult survivors, should be aware of the potential for long-term GH deficiency and adverse cardiovascular and diabetes risk profiles as a consequence of leukemia treatment.

Advances in the diagnosis and treatment of neuroblastoma

Neuroblastoma, a childhood neoplasm arising from neural crest cells, is characterized by a diversity of clinical behavior ranging from spontaneous remission to rapid tumor progression and death. To a large extent, outcome can be predicted by the stage of disease and the age at diagnosis. However, the molecular events responsible for the variability in response to treatment and the rate of tumor growth remain largely unknown. Over the past decade, transformation-linked genetic changes have been identified in neuroblastoma tumors that have contributed to the understanding of tumor predisposition, metastasis, treatment responsiveness, and prognosis. The Children's Oncology Group recently developed a Neuroblastoma Risk Stratification System that is currently in use for treatment stratification purposes, based on clinical and biologic factors that are strongly predictive of outcome. This review discusses the current risk-based treatment approaches for children with neuroblastoma and recent advances in biologic therapy.