Young adult survivors of childhood acute lymphoblastic leukemia: spontaneous GH secretion in relation to CNS radiation

Radiotherapy-induced hypopituitarism: a review

Hypopituitarism is a disorder caused by impaired hormonal secretions from the hypothalamic-pituitary axis. Radiotherapy is the most common cause of iatrogenic hypopituitarism. The hypothalamic-pituitary axis inadvertently gets irradiated in patients receiving prophylactic cranial radiotherapy for leukemia, total body irradiation and radiotherapy for intracranial, base skull, sinonasal and nasopharyngeal tumors. Radiation-induced hypopituitarism (RIH) is insidious, progressive and largely nonreversible. Mostly, RIH involves one hypothalamic-pituitary axis; however, multiple hormonal axes deficiency starts developing at higher doses. Although the clinical effects of the hypopituitarism are more profound in children and young adults, its implications in older adults are being increasingly recognized. The risk continues to persist or increase up to 10 years following radiation exposure. The clinical management of hypopituitarism is challenging both for the patients and healthcare providers. Here we have reviewed the scale of the problem, the risk factors and the management of RIH.

Risk factors for cardiovascular disease are increased in young adults treated with stem cell transplantation during childhood

We measured risk factors for CVD in 18 patients at a median of 18.2 yr after SCT and in sex and age-matched controls. Three patients (17%), but none of the controls, met the criteria for the MetS (p = 0.25). In the patients, we found higher levels of triglycerides (0.94 vs. 0.62 mm, p = 0.019), total cholesterol (5.1 vs. 4.0 mm, p = 0.017), LDL (3.4 vs. 2.6 mm, p = 0.019), apolipoprotein B (1.04 vs. 0.74 g/L, p = 0.004), apolipoprotein B/A1 ratio (0.7 vs. 0.5, p = 0.026), and lower levels of adiponectin (4.9 vs. 7.5 mg/L, p = 0.008) than in the controls. The patients had a lower GHmax (9 vs. 20.7 mU/L, p = 0.002). GHmax was significantly correlated inversely with triglycerides (r = -0.64, p = 0.008), total cholesterol (r = -0.61, p = 0.011), apolipoprotein B (r = -0.60, p = 0.014), and apolipoprotein B/A1 ratio (r = -0.66, p = 0.005). We recorded a significantly thicker carotid intima layer among the patients than among matched controls (0.15 vs. 0.13 mm, p = 0.034). The level of adiponectin correlated inversely with carotid intima thickness (r = -0.55, p = 0.023). After SCT in childhood, long-term survivors may be at risk of developing premature CVD.

Effects of growth hormone therapy on bone mass, metabolic balance, and well-being in young adult survivors of childhood acute lymphoblastic leukemia

Growth hormone deficiency (GHD), mostly after cranial radiotherapy (CRT), may lead to several negative effects. Young adult survivors of acute lymphoblastic leukemia (ALL) could benefit from GH therapy in different ways. Twenty ALL survivors (17.1 ± 4.3 y after diagnosis) with low bone mineral densities and/or low insulin-like growth factor-1 were included. Two of the 3 patients who only received chemotherapy had GHD. Of the 20 patients, 17 started with GH therapy and 14 completed the 2-year study period. At several time points, bone mineral density (BMD) was measured. Psychological functioning was assessed. At the start of the study, standard deviation scores of height, insulin-like growth factor-1, lumbar spine, and femoral neck BMD were all below -1. After 2 years of GH therapy, total body BMD and lean mass were significantly higher (P < 0.01 and P < 0.001, respectively), whereas the percentage fat was significantly lower (P < 0.02). Several psychological measures improved significantly after 2 years. In conclusion, GH therapy during 2 years in young adult survivors of childhood ALL did have a number of benefits, such as improvement of total body bone density and body composition. Results also suggest improvement of psychological well being. Furthermore, it also became clear that patients after chemotherapy alone should be tested for GHD.

Height impairment after lower dose cranial irradiation in children with acute lymphoblastic leukemia

PURPOSE

The purpose of this study is to determine whether height measurements are affected by cranial radiation doses of 12-18 Gy.

PATIENTS AND METHODS

From 1997 to 2007, 23 children received cranial RT for T-cell or pre-B-cell acute lymphoblastic leukemia (ALL). Dose fractionation schemes included 18 Gy in 9 fractions (n = 8), 18 Gy in 10 fractions (n = 5), 12.6 Gy in 7 fractions (n = 6), and 12 Gy in 8 fractions (n = 4). These patients were matched and compared to a control group of 23 patients who had ALL but no cranial RT. Height z-scores at diagnosis and last follow-up were compared using the paired Student's t-test. Differences in z-scores according to host and treatment parameters were compared using the unpaired Student's t-test. Median follow-up for irradiated patients was 63.5 months while for unirradiated patients was 91 months.

RESULTS

The mean z-scores at initial diagnosis and last follow-up were 0.14 and -0.48 for patients receiving 12-12.6 Gy (P = 0.016), -0.16 and -0.89 for 18 Gy (P = 0.003), and 0.34 and 0.22 for no RT (P = 0.62). For children receiving RT, the mean difference in z-scores at initial diagnosis and last follow-up was -0.67 while for those not receiving RT, it was -0.10 (P = 0.043).

CONCLUSION

Children receiving 12-18 Gy cranial RT for ALL were found to have height impairment compared to those not receiving RT.

Glucose metabolism and body composition in young adults treated with TBI during childhood

After SCT in childhood, survivors may develop disorders of glucose metabolism. The role of obesity is controversial. We measured insulin sensitivity using the homeostasis model assessment (HOMA) and the frequently sampled i.v. glucose tolerance test (FSIVGTT), as well as body composition using dual-energy X-ray absorptiometry in 18 young adults median 18.2 years after SCT and compared them with matched controls. We also measured growth hormone (GH) secretion, and levels of leptin and adiponectin. HOMA showed insulin resistance in eight patients (44%), as opposed to none of the controls (P=0.008) and FSIVGTT showed a decreased sensitivity index in the patients (2.98 vs 4.54 mU/L/min, P=0.042). Dual energy X-ray absorptiometry showed a higher percentage fat mass in the patients (34.9 vs 24.3%, P=0.011), which correlated inversely with the sensitivity index (r=-0.52, P=0.032). The patients had a lower peak value of GH (GH(max) 9 vs 20.7 mU/L, P=0.002). Time post SCT correlated with percentage fat mass and inversely with GH(max). The patients had higher levels of leptin and lower levels of adiponectin, even after adjustment for fat mass. We propose that the decreased insulin sensitivity may primarily be explained by the adverse body composition, which may owe to long-standing GH deficiency.

Height deficit during and many years after treatment for acute lymphoblastic leukemia in children: a review

There are conflicting data on the incidence and severity of height deficits in children with acute lymphoblastic leukemia (ALL). This is probably due to: (1) collection of data in different phases of treatment; (2) differences in chemotherapeutic regimens; (3) inclusion or not of children who had received cranial irradiation (CRT); (4) limited numbers of patients; (5) relative numbers of prepubertal and pubertal children; (6) different ways of measuring growth deficits. Twenty-five papers published between 1987 and 2006 were reviewed. These reveal that (1) chemotherapy always causes some height reduction during treatment regardless of whether additional CRT is given; (2) catch-up growth occurs immediately after cessation of treatment; (3) intensive chemotherapy alone significantly decreases height in the long-term but to a lesser extent than with additional CRT; (4) young children develop more severe height loss; (5) girls are reported to have greater height deficits but confounding factors have not been adequately considered; (6) late growth hormone (GH) deficiency has been detected in many children, mostly in those who had CRT; (7) GH replacement therapy seems to be effective. ALL relapse in GH-treated children is not more common than in those not treated with GH.

Exercise echocardiography reveals subclinical cardiac dysfunction in young adult survivors of childhood acute lymphoblastic leukemia

OBJECTIVE

Anthracyclines (AC) have contributed significantly to increased survival rate in acute lymphoblastic leukemia (ALL), although the use of these drugs is limited due to cardiotoxicity. The aim was to evaluate heart muscle function in asymptomatic adult survivors of ALL treated in early childhood in relation to the combined effects of AC and other potential cardiotoxic factors.

PROCEDURE

Twenty-three young adult ALL survivors who had all received treatment with median 120 (120-400) mg AC/m(2) before the onset of puberty were examined median 21 years after remission and compared with 12 healthy controls. Basal echocardiography including two-dimensional (2D) M-mode and Doppler examination was performed, followed by a maximal exercise stress test and stress echocardiography immediately after stress test and after 5 min recovery.

RESULTS

We found significant differences in systolic function between patients and controls at maximal exercise despite absence of reported symptoms from the patients. The most marked difference was in ejection fraction at stress 59.5% (32.6-81.1) and 77.3% (66.2-85.3), respectively (P < 0.00006). Ten out of 23 patients reduced their ejection fraction at stress compared with at rest; this was not found in any of the controls. Cardiovascular risk factors such as GH deficiency and a high proportion of trunk fat did not have an impact on cardiac function.

CONCLUSIONS

With very long follow up in a homogenous cohort of ALL survivors, we found subclinical cardiac dysfunction with exercise stress echocardiography even after low doses of AC.

Osteopenia and cancer in children and adolescents: the fragility of success

The attainment of a satisfactory peak bone mass, which is accomplished largely by the end of adolescence, is the best protection against excessive bone mineral loss in late adulthood. Factors that influence this process include age, race, sex, body size, pubertal status, diet, physical activity, and other lifestyle elements. Cancer and its treatment in children and teenagers adversely impact bone mineralization. In particular, chemotherapy (especially glucocorticosteroids and methotrexate) and cranial irradiation (apparently by reducing growth hormone secretion and by causing hypogonadotropic hypogonadism) interfere with normal bone turnover. Resorption often exceeds formation, resulting in net bone mineral loss and providing a rational basis for the use of antiresorptive drugs. Such osteopenia may be symptomatic, with pain and abnormal gait, and increases the risk of fractures several fold. The disorder is compounded by reduced physical activity, so programs to reduce this deficit are of measurable benefit. All of those engaged in the care of children and adolescents with cancer have an opportunity to improve the bone health of these young people and to limit their risk of developing osteoporosis and fragility fractures in adult life.

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.