Risk of leukemia in children treated with human growth hormone: review and reanalysis

Long-term risk of neoplastic events after childhood growth hormone treatment: a population-based cohort study in Sweden

Background

Increased risk of neoplastic events after recombinant human growth hormone (rhGH) treatment in childhood has been an ongoing concern but long-term safety data are limited.

Methods

A nationwide population-based cohort study in Sweden of patients treated with rhGH during childhood between 1985-2010, due to isolated growth hormone deficiency (GHD), small for gestational age (SGA) and idiopathic short stature (ISS). The comparison group consisted of 15 age-, sex-, and region-matched controls per patient, randomly selected from the general population. Data on neoplastic events and covariates, such as gestational age, birth weight, birth length, socioeconomic status, and height at study start, were collected through linkage with population-based registers. The cohort was followed for neoplastic events until the end of 2020.

Results

53,444 individuals (3,408 patients; 50,036 controls) were followed for up to 35 years, with a median follow-up of 19.8 years and a total of 1,050,977 person-years. Patients showed a moderately increased hazard ratio (HR) for neoplastic events overall compared to controls (HR 1.28, 95% CI: 1.12-1.46), but only significant for males (HR 1.39, 95% CI: 1.17-1.66) and not females (HR 1.15, 95% CI: 0.94-1.41). Longer treatment duration was associated with an increased HR, but no association was found between neoplastic events and mean or cumulative dose. No increased risk of malignant neoplasms was observed for the patients compared to matched controls (HR 0.91 95% CI: 0.66-1.26).

Conclusion

No association was found between rhGH treatment during childhood for GHD, SGA, or ISS and malignant neoplastic events in early to mid-adulthood. A moderate increase in overall neoplastic events was observed due to an increased number of events in male patients.

Hormone replacement in survivors of childhood cancer and brain tumors: safety and controversies

Childhood cancer survivors are at risk for developing endocrine disorders, including deficits in growth hormone, thyroid hormone and sex hormones. The influence these hormones have on cell growth and metabolism has raised concerns regarding the safety of their use as treatments in survivors of childhood cancer and brain tumors. This article offers a summary of current knowledge, controversies and areas for future research pertaining to this area.

Association Between Recombinant Growth Hormone Therapy and All-Cause Mortality and Cancer Risk in Childhood: Systematic Review and Meta-Analysis

OBJECTIVES

The safety of recombinant human growth hormone (rhGH) treatment in childhood and the role of rhGH therapy in promoting tumorigenesis and progression have been the subject of debate for decades. We aimed to systematically assess the relationship between rhGH therapy in children and adolescents and clinical outcomes, including all-cause mortality, cancer mortality, cancer incidence, and risk of the second neoplasm.

METHODS

Literature retrieval, study selection, and data extraction were completed independently and in duplicate. Effect-size estimates are expressed as standardized mortality ratios (SMRs), standardized incidence ratio (SIR), and relative risk (RR) with a 95% CI.

RESULTS

Data from 24 articles, involving 254,776 persons, were meta-analyzed. Overall analyses revealed the association of rhGH therapy was not statistically significant with all-cause mortality (SMR = 1.28; 95% CI: 0.58-2.84; P = 0.547; I ² = 99.2%; Tau² = 2.154) and cancer mortality (SMR = 2.59; 95% CI: 0.55-12.09; P = 0.228; I ² = 96.7%; Tau² = 2.361) and also cancer incidence (SIR = 1.54; 95% CI: 0.68-3.47; P = 0.229; I ² = 97.5%; Tau² = 2.287), yet statistical significance was observed for second neoplasm (RR = 1.77; 95% CI: 1.33-2.35; P = 0.001; I ² = 26.7%; Tau² = 0.055). Differences in the geographic region, gender, treatment duration, mean rhGH dose, overall rhGH exposure dose, and initial disease accounted for heterogeneity in the subgroup analyses.

CONCLUSION

Our findings indicate that the rhGH therapy is not related to all-cause mortality and cancer mortality and cancer incidence, yet it seems to trigger a second tumor risk. Future prospective studies are needed to confirm our findings and answer the more challenging question regarding the optimal dose of rhGH therapy in children and adolescents.

Management of Short Stature: Use of Growth Hormone in GH-Deficient and non-GH-Deficient Conditions

Growth hormone (GH) is an important driver for somatic growth and increase in height in children. The development of recombinant human GH has greatly increased its availability, and hence the potential for its use and abuse. GH therapy should only be offered to patients with established and approved indications. Common pediatric indications for treatment include growth hormone deficiency, Turner syndrome, Prader-Willi syndrome, small for gestational age, chronic renal insufficiency, and idiopathic short stature. Before initiating treatment, the family should be counseled about the treatment goals, costs, and possible adverse effects from the treatment. It is important for patients to have realistic expectations from the treatment. The dose of GH should be individualized for the indication and will require titration in each patient based on response to the treatment and the adverse effects. Overall, GH has a good safety record. However, GH treatment has many potential and real adverse effects that need to be considered and monitored during treatment. Recently, safety concerns regarding the long-term effect of GH therapy on cardiovascular morbidity have come under scrutiny.

Role of the GH-IGF1 system in progression of cancer

Emerging evidence links the growth hormone (GH)-insulin-like growth factor-1 (IGF1) endocrine axis to cancer development. While this putative correlation is of major translational relevance, most clinical and epidemiological reports to date found no causal linkage between GH therapy and enhanced cancer risk. Thus, it is generally agreed that GH therapy constitutes a safe pharmacological intervention. The present review focuses on a number of issues in the area of GH-IGF1 action in cancer development. Emphasis is given to the idea that GH and IGF1 do not conform to the definition of oncogenic factors. Specifically, these hormones, even at high pharmacological doses, are unable to induce malignant transformation. However, the GH-IGF1 axis is capable of 'pushing' already transformed cells through the various phases of the cell cycle. Viral and cellular oncogenes require an intact IGF1 signaling pathway in order to elicit transformation; in other words, oncogenic agents adopt the IGF1 pathway. This universal mechanism of action of oncogenes has broad implications in oncology. Our review provides an in-depth analysis of the interplay between the GH-IGF1 axis and cancer genes, including tumor suppressors p53 and BRCA1. Finally, the safety of GH therapy in both children and adults needs further long-term follow-up studies.

Downregulation of the GHRH/GH/IGF1 axis in a mouse model of Börjeson-Forssman-Lehman syndrome

Börjeson-Forssman-Lehmann syndrome (BFLS) is an intellectual disability and endocrine disorder caused by plant homeodomain finger 6 (PHF6) mutations. Individuals with BFLS present with short stature. We report a mouse model of BFLS, in which deletion of Phf6 causes a proportional reduction in body size compared with control mice. Growth hormone (GH) levels were reduced in the absence of PHF6. Phf6 ^{- /Y} animals displayed a reduction in the expression of the genes encoding GH-releasing hormone (GHRH) in the brain, GH in the pituitary gland and insulin-like growth factor 1 (IGF1) in the liver. Phf6 deletion specifically in the nervous system caused a proportional growth defect, indicating a neuroendocrine contribution to the phenotype. Loss of suppressor of cytokine signaling 2 (SOCS2), a negative regulator of growth hormone signaling partially rescued body size, supporting a reversible deficiency in GH signaling. These results demonstrate that PHF6 regulates the GHRH/GH/IGF1 axis.

Acquired neuro-secretory defect in growth hormone secretion due to Imatinib mesylate and the efficacy of growth hormone therapy in children with chronic myeloid leukemia

Imatinib results in growth retardation in children with chronic myeloid leukemia (CML). The study was planned to assess the GHRH-GH-IGF1 axis in children with CML, receiving Imatinib and to evaluate the efficacy of human growth hormone (hGH) therapy. Twenty children with CML, receiving Imatinib for a period exceeding 6 months, with resultant growth retardation were included. The GHRH-GH-IGF1 axis was assessed using growth hormone stimulation tests. IGF-1 generation test was performed for the evaluation of GH insensitivity. The mean age at inclusion was 15.2 years. The mean duration of treatment with Imatinib was 5.7 years. The mean decrease in height SDS since the start of Imatinib was -0.95 (p = 0.008). IGF-1 SDS was <-2 in all the patients. 71.4% of patients had a suboptimal GH response following stimulation with GHRH-Arginine. All patients had stimulable, although a delayed GH response with glucagon stimulation. 20% of patients had GH insensitivity. Four patients were treated with hGH for a mean duration of 5.75 months, achieved normalization of IGF-1 levels and improvement in growth velocity improved from 0.21 to 0.86 cm/month. Imatinib results in an acquired neurosecretory defect in GH secretion. Treatment with growth hormone leads to an improvement in growth velocity and normalization of IGF-1.

Growth Hormone's Links to Cancer

Several components of the GH axis are involved in tumor progression, and GH-induced intracellular signaling has been strongly associated with breast cancer susceptibility in genome-wide association studies. In the general population, high IGF-I levels and low IGF-binding protein-3 levels within the normal range are associated with the development of common malignancies, and components of the GH-IGF signaling system exhibit correlations with clinical, histopathological, and therapeutic parameters in cancer patients. Despite promising findings in preclinical studies, anticancer therapies targeting the GH-IGF signaling system have led to disappointing results in clinical trials. There is substantial evidence for some degree of protection against tumor development in several animal models and in patients with genetic defects associated with GH deficiency or resistance. In contrast, the link between GH excess and cancer risk in acromegaly patients is much less clear, and cancer screening in acromegaly has been a highly controversial issue. Recent studies have shown that increased life expectancy in acromegaly patients who attain normal GH and IGF-I levels is associated with more deaths due to age-related cancers. Replacement GH therapy in GH deficiency hypopituitary adults and short children has been shown to be safe when no other risk factors for malignancy are present. Nevertheless, the use of GH in cancer survivors and in short children with RASopathies, chromosomal breakage syndromes, or DNA-repair disorders should be carefully evaluated owing to an increased risk of recurrence, primary cancer, or second neoplasia in these individuals.

Safety Outcomes During Pediatric GH Therapy: Final Results From the Prospective GeNeSIS Observational Program

Context

Safety concerns have been raised regarding premature mortality, diabetes, neoplasia, and cerebrovascular disease in association with GH therapy.

Objective

To assess incidence of key safety outcomes.

Design

Prospective, multinational, observational study (1999 to 2015).

Setting

A total of 22,311 GH-treated children from 827 investigative sites in 30 countries.

Patients

Children with growth disorders.

Interventions

GH treatment.

Main outcome measures

Standardized mortality ratio (SMR) and standardized incidence ratio (SIR) with 95% CIs for mortality, diabetes, and primary cancer using general population registries.

Results

Predominant short stature diagnoses were GH deficiency (63%), idiopathic short stature (13%), and Turner syndrome (8%), with mean ± SD follow-up of 4.2 ± 3.2 years (∼92,000 person-years [PY]). Forty-two deaths occurred in patients with follow-up, with an SMR (95% CI) of 0.61 (0.44, 0.82); the SMR was elevated for patients with cancer-related organic GH deficiency [5.87 (3.21, 9.85)]. Based on 18 cases, type 2 diabetes mellitus (T2DM) risk was elevated [SIR: 3.77 (2.24, 5.96)], but 72% had risk factors. In patients without cancer history, 14 primary cancers were observed [SIR: 0.71 (0.39, 1.20)]. Second neoplasms occurred in 31 of 622 cancer survivors [5.0%; 10.7 (7.5, 15.2) cases/1000 PY] and intracranial tumor recurrences in 67 of 823 tumor survivors [8.1%; 16.9 (13.3, 21.5) cases/1000 PY]. All three hemorrhagic stroke cases had risk factors.

Conclusions

GeNeSIS (Genetics and Neuroendocrinology of Short Stature International Study) data support the favorable safety profile of pediatric GH treatment. Overall risk of death or primary cancer was not elevated in GH-treated children, and no hemorrhagic strokes occurred in patients without risk factors. T2DM incidence was elevated compared with the general population, but most cases had diabetes risk factors.

Long-term safety of growth hormone-A combined registry analysis

OBJECTIVES

Preliminary data from the French cohort of the Safety and Appropriateness of Growth hormone treatments in Europe (SAGhE) study raised concerns regarding the safety of recombinant human GH, suggesting that GH may increase mortality and incidence of stroke in patients treated during childhood for GH deficiency or short stature. We evaluated published safety data, focusing on mortality, neoplasms, cerebrovascular events and diabetes across a number of large-scale pharmaceutical company GH registries.

DESIGN

A literature review was conducted using PubMed, EMBASE and Google Scholar to identify all relevant safety data from manufacturers' GH registries published between 1988 and April 2016. Results were hand-sorted to exclude nonrelevant publications; bibliographic references from retrieved articles were evaluated for any additional references.

RESULTS

The published data do not support an increased risk of mortality in children or adults treated with GH. There was no evidence of an increased risk of stroke, new malignancy, leukaemia, nonleukaemic extracranial tumours or recurrence of intracranial malignancy in patients without risk factors. The risk of a second neoplasm is increased, particularly if patients have received radiation therapy for a central nervous system tumour. There may be an increased risk of type 2 diabetes in GH-treated patients, but this appears to be confined to those with pre-existing risk factors.

CONCLUSIONS

Patients with risk factors for malignancy or type 2 diabetes should be treated with caution and monitored during follow-up, but current published data provide reassurance on the long-term safety profile of GH in patients receiving GH treatment.

The Growth Hormone Receptor: Mechanism of Receptor Activation, Cell Signaling, and Physiological Aspects

The growth hormone receptor (GHR), although most well known for regulating growth, has many other important biological functions including regulating metabolism and controlling physiological processes related to the hepatobiliary, cardiovascular, renal, gastrointestinal, and reproductive systems. In addition, growth hormone signaling is an important regulator of aging and plays a significant role in cancer development. Growth hormone activates the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway, and recent studies have provided a new understanding of the mechanism of JAK2 activation by growth hormone binding to its receptor. JAK2 activation is required for growth hormone-mediated activation of STAT1, STAT3, and STAT5, and the negative regulation of JAK-STAT signaling comprises an important step in the control of this signaling pathway. The GHR also activates the Src family kinase signaling pathway independent of JAK2. This review covers the molecular mechanisms of GHR activation and signal transduction as well as the physiological consequences of growth hormone signaling.

Controversies in the risk of neoplasia in GH deficiency

Growth hormone (GH) replacement in GH deficient (GHD) children secures normal linear growth, while in GHD adults it improves metabolic status, body composition and quality of life. Safety of GH treatment is an important issue in particular concerning the controversy of potential cancer risk. Unlike in congenital IGF-1 deficiency, there is no complete protection against cancer in GHD patients. Important modifiable risk factors in GHD patients are obesity, insulin resistance, sedentary behavior, circadian rhythm disruption, chronic low grade inflammation and concomitant sex hormone replacement. Age, family history, hereditary cancer predisposition syndromes or cranial irradiation may present non-modifiable risk factors. Quantifying the risk of cancer in relation to GH therapy in adult GHD patients is complex. There is evidence that links GH to cancer occurrence or promotion, but the evidence is progressively weaker when moving from in vitro studies to in vivo animal studies to epidemiological studies and finally to studies on GH treated patients. GH-IGF inhibition in experimental animals leads to decreased cancer incidence and progression. Epidemiological studies suggest an association of high normal circulating IGF-1 or GH to cancer incidence in general population. Data regarding cancer incidence in acromegaly are inconsistent but thyroid and colorectal neoplasias are the main source of concern. Replacement therapy with rhGH for GHD is generally safe. Overall the rate of de novo cancers was not increased in studies of GH-treated GHD patients. Additional caution is mandated in patients with history of cancer, strong family history of cancer and with advancing age. Childhood cancer survivors may be at increased risk for secondary neoplasms compared with general population. In this subgroup GH therapy should be used cautiously and with respect to other risk factors (cranial irradiation etc). We believe that the benefits of GH therapy against the morbidity of untreated GH deficiency outweigh the theoretical cancer risk. Proper monitoring of GH treatment with diligent cancer surveillance remains essential.

Treatment of growth hormone deficiency in children, adolescents and at the transitional age

Recombinant human growth hormone (rhGH) has been available since 1985. Before 1985 growth hormone (GH) was extracted from cadaveric pituitary glands, but this was stopped in most countries that year, following the recognition that it could transmit Creutzfeldt-Jacob disease. The primary goal of rhGH treatment in GHD patients is to normalize height during childhood and adolescence and attain an adult height within the normal range and within the target height range (genetic potential). Genome-wide association studies have been used increasingly to study the genetic influence on height. There is a wide response to rhGH therapy, likely due to compliance issues, severity of GH deficiency and patient's sensitivity to rhGH. While some pediatric endocrinologists will use a fixed dose of rhGH, most will use an auxology-based dosing approach. This will involve starting at the lower end of the dose range and then titrating upwards based on the patient's response to therapy with measurement of IGF-1 concentrations to ensure that the patient is not over treated or undertreated. Although treatment of children with GHD with rhGH has generally been safe, careful follow-up by a pediatric endocrinologist in partnership with the pediatrician or primary care physician is recommended. The aim of this paper is to review the strategies and recommendations for treatment of GHD in children and patients in the transition to adult care.

Is there an effect of ghrelin/ghrelin analogs on cancer? A systematic review

Ghrelin is a hormone with multiple physiologic functions, including promotion of growth hormone release, stimulation of appetite and regulation of energy homeostasis. Treatment with ghrelin/ghrelin-receptor agonists is a prospective therapy for disease-related cachexia and malnutrition. In vitro studies have shown high expression of ghrelin in cancer tissue, although its role including its impact in cancer risk and progression has not been established. We performed a systematic literature review to identify peer-reviewed human or animal in vivo original research studies of ghrelin, ghrelin-receptor agonists, or ghrelin genetic variants and the risk, presence, or growth of cancer using structured searches in PubMed database as well as secondary searches of article reference lists, additional reviews and meta-analyses. Overall, 45 (73.8%) of the 61 studies reviewed, including all 11 involving exogenous ghrelin/ghrelin-receptor agonist treatment, reported either a null (no statistically significant difference) or inverse association of ghrelin/ghrelin-receptor agonists or ghrelin genetic variants with cancer risk, presence or growth; 10 (16.7%) studies reported positive associations; and 6 (10.0%) reported both negative or null and positive associations. Differences in serum ghrelin levels in cancer cases vs controls (typically lower) were reported for some but not all cancers. The majority of in vivo studies showed a null or inverse association of ghrelin with risk and progression of most cancers, suggesting that ghrelin/ghrelin-receptor agonist treatment may have a favorable safety profile to use for cancer cachexia. Additional large-scale prospective clinical trials as well as basic bioscientific research are warranted to further evaluate the safety and benefits of ghrelin treatment in patients with cancer.

Description of the SAGhE Cohort: A Large European Study of Mortality and Cancer Incidence Risks after Childhood Treatment with Recombinant Growth Hormone

BACKGROUND

The long-term safety of growth hormone treatment is uncertain. Raised risks of death and certain cancers have been reported inconsistently, based on limited data or short-term follow-up by pharmaceutical companies.

PATIENTS AND METHODS

The SAGhE (Safety and Appropriateness of Growth Hormone Treatments in Europe) study assembled cohorts of patients treated in childhood with recombinant human growth hormone (r-hGH) in 8 European countries since the first use of this treatment in 1984 and followed them for cause-specific mortality and cancer incidence. Expected rates were obtained from national and local general population data. The cohort consisted of 24,232 patients, most commonly treated for isolated growth failure (53%), Turner syndrome (13%) and growth hormone deficiency linked to neoplasia (12%). This paper describes in detail the study design, methods and data collection and discusses the strengths, biases and weaknesses consequent on this.

CONCLUSION

The SAGhE cohort is the largest and longest follow-up cohort study of growth hormone-treated patients with follow-up and analysis independent of industry. It forms a major resource for investigating cancer and mortality risks in r-hGH patients. The interpretation of SAGhE results, however, will need to take account of the methods of cohort assembly and follow-up in each country.

Risk of Neoplasia in Pediatric Patients Receiving Growth Hormone Therapy--A Report From the Pediatric Endocrine Society Drug and Therapeutics Committee

CONTEXT

GH and IGF-1 have been shown to affect tumor growth in vitro and in some animal models. This report summarizes the available evidence on whether GH therapy in childhood is associated with an increased risk of neoplasia during treatment or after treatment is completed.

EVIDENCE ACQUISITION

A PubMed search conducted through February 2014 retrieved original articles written in English addressing GH therapy and neoplasia risk. Subsequent searches were done to include additional relevant publications.

EVIDENCE SYNTHESIS

In children without prior cancer or known risk factors for developing cancer, the clinical evidence does not affirm an association between GH therapy during childhood and neoplasia. GH therapy has not been reported to increase the risk for neoplasia in this population, although most of these data are derived from postmarketing surveillance studies lacking rigorous controls. In patients who are at higher risk for developing cancer, current evidence is insufficient to conclude whether or not GH further increases cancer risk. GH treatment of pediatric cancer survivors does not appear to increase the risk of recurrence but may increase their risk for subsequent primary neoplasms.

CONCLUSIONS

In children without known risk factors for malignancy, GH therapy can be safely administered without concerns about an increased risk for neoplasia. GH use in children with medical diagnoses predisposing them to the development of malignancies should be critically analyzed on an individual basis, and if chosen, appropriate surveillance for malignancies should be undertaken. GH can be used to treat GH-deficient childhood cancer survivors who are in remission with the understanding that GH therapy may increase their risk for second neoplasms.

Growth hormone replacement in patients with a history of malignancy: a review of the literature and best practice for offering treatment

Previous studies have implicated the growth hormone (GH)/IGF-I axis as an important mediator of cancer risk in humans and animals. Evidence supporting this notion is derived from animal studies, epidemiological observations, patients with acromegaly and from therapeutic manipulation of GH and IGF-I actions. Therefore, the use of GH therapy in patients with a history of malignancy raises hypothetical safety concerns. Reassuringly, GH therapy in childhood cancer survivors has not been confirmed to increase the cancer risk. Conversely, the risk of occurrence of a second neoplasm may be increased, with meningiomas being the most common tumor. In light of these findings, we propose considering GH therapy to be based on each individual's circumstance and commenced at least 2 years after cancer remission is achieved with close monitoring during therapy. More long-term data are needed on the safety of GH replacement therapy in GH-deficient adults with a history of malignancy.

Growth hormone treatment and risk of malignancy

Growth hormone (GH) treatment has been increasingly widely used for children with GH deficiencies as the survival rate of pediatric patients with malignancies has increased. Both GH and insulin-like growth factor-I have mitogenic and antiapoptotic activity, prompting concern that GH treatment may be associated with tumor development. In this review, the authors examined the relationship between GH treatment and cancer risk in terms of de novo malignancy, recurrence, and secondary neoplasm. Although the results from numerous studies were not entirely consistent, this review of various clinical and epidemiological studies demonstrated that there is no clear evidence of a causal relationship between GH treatment and tumor development. Nonetheless, a small number of studies reported that childhood cancer survivors who receive GH treatment have a small increased risk of developing de novo cancer and secondary malignant neoplasm. Therefore, regular follow-ups and careful examination for development of cancer should be required in children who receive GH treatment. Continued surveillance for an extended period is essential for monitoring long-term safety.

Comparison between the growth response to growth hormone (GH) therapy in children with partial GH insensitivity or mild GH deficiency

OBJECTIVES

GH therapy is still controversial, except in severe GH deficiency (SGHD). The objective of this study was to compare the response to growth hormone (GH) therapy in children with partial GH insensitivity (PGHIS) and mild GH deficiency (MGHD) with those with SGHD.

SUBJECTS AND METHODS

Fifteen PGHIS, 11 MGHD, and 19 SGHD subjects, followed up for more than one year in the Brazilian public care service, were evaluated regarding anthropometric and laboratory data at the beginning of treatment, after one year (1st year) on treatment, and at the last assessment (up to ten years in SGHD, up to four years in MGHD, and up to eight years in PGHIS).

RESULTS

Initial height standard deviation score (SDS) in SGHD was lower than in MGHD and PGHIS. Although the increase in 1 st year height SDS in comparison to initial height SDS was not different among the groups, height-SDS after the first year of treatment remained lower in SGHD than in MGHD. There was no difference in height-SDS at the last assessment of the children among the three groups. GH therapy, in the entire period of observation, caused a trend towards lower increase in height SDS in PGHIS than SGHD but similar increases were observed in MGHD and SGHD.

CONCLUSION

GH therapy increases height in PGHIS and produces similar height effects in MGHD and SGHD.

Growth Hormone and Treatment Controversy; Long Term Safety of rGH

The availability of recombinant human growth hormone (rGH) for treatment of growth disorders has provided an unlimited supply for replacement in patients with growth hormone insufficiency but also for short stature due to Turner syndrome, renal failure, Prader-Willi syndrome, small for gestational age and idiopathic short stature. Considering the potential for side effects in the use of a growth promoting agent, the community of physicians and pharmaceutical manufacturers developed systematic methods to survey for short and long term effects. Recently published data from the National Cooperative Growth Study (NCGS), managed by Genentech, concluded that GH has a 'favorable profile'. In 2012, results from the European Union's Safety and Appropriateness of GH treatment in Europe (EU SAGhE) study about the long term mortality in GH treated patients were published in two separate manuscripts. This review will examine the issue of safety of rGH in order that practitioners are informed as they consider initiation of therapy with patients.

Safety of growth hormone treatment in patients previously treated for cancer

This review provides an overview of the safety of growth hormone replacement therapy in individuals previously treated for cancer. The review focuses on the risk of disease recurrence and second neoplasm occurrence with special attention to data on childhood cancer survivors.

Growth hormone, the insulin-like growth factor axis, insulin and cancer risk

Growth hormone (GH), insulin-like growth factor (IGF)-I and insulin have potent growth-promoting and anabolic actions. Their potential involvement in tumor promotion and progression has been of concern for several decades. The evidence that GH, IGF-I and insulin can promote and contribute to cancer progression comes from various sources, including transgenic and knockout mouse models and animal and human cell lines derived from cancers. Assessments of the GH-IGF axis in healthy individuals followed up to assess cancer incidence provide direct evidence of this risk; raised IGF-I levels in blood are associated with a slightly increased risk of some cancers. Studies of human diseases characterized by excess growth factor secretion or treated with growth factors have produced reassuring data, with no notable increases in de novo cancers in children treated with GH. Although follow-up for the vast majority of these children does not yet extend beyond young adulthood, a slight increase in cancers in those with long-standing excess GH secretion (as seen in patients with acromegaly) and no overall increase in cancer with insulin treatment, have been observed. Nevertheless, long-term surveillance for cancer incidence in all populations exposed to increased levels of GH is vitally important.

Growth hormone treatment in children is not associated with an increase in the incidence of cancer: experience from KIGS (Pfizer International Growth Database)

OBJECTIVE

To assess the incidence of cancer in patients treated with growth hormone (GH) in KIGS - the Pfizer International Growth Database-without cancer or any other condition in medical history known to increase the risk of cancer.

STUDY DESIGN

Data were analyzed from patients with growth disorders enrolled in an observational survey KIGS who had no known increased risk of developing cancer before starting recombinant human GH treatment. The incidence of cancer in this patient cohort (overall, site-specific, and according to etiology of growth disorder) was compared with the incidence in the general population by using the standardized incidence ratio (ie, relating the observed to expected number of cases with stratification for age, sex, and country).

RESULTS

A total of 32 new malignant neoplasms were reported in 58 603 patients, versus the 25.3 expected (incidence, 16.4 per 100 000 patient-years; standardized incidence ratio, 1.26; 95% confidence interval, 0.86-1.78). No category of growth disorder showed a statistically significant difference in observed compared with the expected number of cases.

CONCLUSION

There is no evidence in this series that GH treatment in young patients with growth disorders results in an increased risk of developing cancer relative to that expected in the normal population. However, surveillance for an extended time should continue to allow further assessment.

Carcinogenicity assessments of biotechnology-derived pharmaceuticals: a review of approved molecules and best practice recommendations

An important safety consideration for developing new therapeutics is assessing the potential that the therapy will increase the risk of cancer. For biotherapeutics, traditional two-year rodent bioassays are often not scientifically applicable or feasible. This paper is a collaborative effort of industry toxicologists to review past and current practice regarding carcinogenicity assessments of biotherapeutics and to provide recommendations. Publicly available information on eighty marketed protein biotherapeutics was reviewed. In this review, no assessments related to carcinogenicity or tumor growth promotion were identified for fifty-one of the eighty molecules. For the twenty-nine biotherapeutics in which assessments related to carcinogenicity were identified, various experimental approaches were employed. This review also discusses several key principles to aid in the assessment of carcinogenic potential, including (1) careful consideration of mechanism of action to identify theoretical risks, (2) careful investigation of existing data for indications of proliferative or immunosuppressive potential, and (3) characterization of any proliferative or immunosuppressive signals detected. Traditional two-year carcinogenicity assays should not be considered as the default method for assessing the carcinogenicity potential of biotherapeutics. If experimentation is considered warranted, it should be hypothesis driven and may include a variety of experimental models. Ultimately, it is important that preclinical data provide useful guidance in product labeling.

Obstacles to the prescribing of growth hormone in children with chronic kidney disease

Despite its effectiveness, recombinant human growth hormone (rhGH) is under-utilized in short children with chronic kidney disease (CKD). We conducted a multicenter study to explore the obstacles preventing children with CKD from receiving rhGH. We investigated the use of rhGH in 307 children with CKD from seven pediatric nephrology centers. Among the 110 patients who fell below the 5th percentile, 56 (51%) had not received rhGH. The most common reasons given for these children not receiving rhGH were family refusal, secondary hyperparathyroidism, and non-compliance. However, no explanation was apparent for 25% of the short children with CKD. Boys were more likely than girls to receive rhGH (65% vs 31%; P = 0.002). Use of rhGH was similar in African Americans and non-Hispanic Whites. Children who had received rhGH achieved a 0.5 increase in height z-score in the first year after the initiation of rhGH therapy. Children who had not received rhGH achieved a 0.03 increase in height z-score during the first year after falling below the 5th percentile (P = 0.005 vs the children who had received rhGH). Waiting for insurance company approval led to a significant delay in the initiation of rhGH treatment in 18% of patients. The fact that more than 50% of short children with CKD did not receive rhGH is secondary to multiple factors, many of which may be amenable to intervention efforts.

Recombinant human growth hormone: rationale for use in the treatment of HIV-associated lipodystrophy

The role of hormonal and metabolic alterations in HIV-associated lipodystrophy syndrome is not yet clear. In patients with HIV-1 undergoing antiretroviral treatment, lipodystrophy is associated with peripheral fat wasting and central adiposity, dyslipidemia, insulin resistance, and increased intramuscular fat accumulation. In HIV lipodystrophy, changes in fat distribution are heterogeneous and can include reduced subcutaneous fat as well as increased visceral fat. In the literature, there is evidence showing that overnight growth hormone (GH) secretion and pulse amplitude decrease in patients with HIV lipodystrophy, with rates of response to standardized GH stimulation being abnormal in at least 20% of these patients. Excess accumulation of visceral fat, central obesity, and increased intra-abdominal adiposity are also typical features of patients with GH deficiency. Recombinant human GH (rhGH) is a potential treatment to diminish excess visceral fat. Our group recently demonstrated that GH therapy in HIV-infected patients with syndromes of fat accumulation produced a significant decrease in body fat and a gain in lean tissue. In this article, we discuss the origin of lipodystrophy in HIV patients, and the use of rhGH treatment (benefits and adverse effects) in HIV-related lipodystrophy.

Acromegaly, growth hormone and cancer risk

Acromegaly is an endocrine disorder characterized by sustained hypersecretion of growth hormone (GH) with concomitant elevation of insulin-like growth factor I (IGF-I) associated with premature mortality from cardiopulmonary diseases and certain malignancies. In particular, there is a two-fold increased risk of developing colorectal cancer. Possible mechanisms underlying this association include elevated levels of circulating GH and IGF-I, but several other plausible processes may be relevant. In a parallel literature, there has been debate whether GH replacement therapy is associated with increased cancer risk in three scenarios: (1) tumour recurrence in children with previously treated cancer; (2) second neoplasms (SNs) in survivors of childhood cancer treated with GH; and (3) de-novo cancer in non-cancer patients treated with GH. The general evidence suggests no increased risk in scenario 1. Through a maze of complex study designs, there is inconclusive evidence of a very modest increase in cancer risk in treated GH-deficiency patients in scenarios 2 and 3, but it is likely that the cumulative risk equates to that of the general population. This emphasizes the need for patient selection balanced against the known morbidity of untreated GH deficiency.

Idiopathic short stature: management and growth hormone treatment

In the management of ISS auxological, biochemical, psychosocial and ethical elements have to be considered. In boys with constitutional delay of growth and puberty androgens are effective in increasing height and sexual characteristics, but adult height is unchanged. GH therapy is efficacious in increasing height velocity and adult height, but the inter-individual variation is considerable. The effect on psychosocial status is uncertain. Factors affecting final height gain include GH dose, height deficit in comparison to midparental height, age and first year height velocity. In case of a low predicted adult height at the onset of puberty, addition of a GnRH analogue can be considered. Although GH therapy appears safe, long-term monitoring is recommended.

Growth hormone therapy for short children born small for gestational age

Children born small for gestational age may demonstrate continued growth retardation, resulting in persistent short stature. In the majority of the cases, this is linked with abnormal growth hormone secretion and also abnormal insulin-like growth factor levels. This review discusses the treatment of such children with recombinant human growth hormone. It illustrates the importance of starting therapy early, the dose-dependent response, and the advantages of continuous therapy and describes safety considerations.

Factors and markers of growth hormone secretion and gonadal function in Fanconi anemia

Many factors may be involved in the growth and gonadal dysfunction of Fanconi anemia (FA).

OBJECTIVE

To evaluate the (1) relationship between FA presentation, including genital abnormalities and pituitary stalk interruption syndrome (PSIS), (2) markers of growth hormone (GH) deficiency and gonadal function, and (3) factors influencing final height and gonadal function.

PATIENTS

Twenty five patients with FA were included, 17 of them were given bone marrow transplantation.

RESULTS

Six patients were diagnosed with GH deficiency and PSIS (group A), whereas 19 had no evidence of GH deficiency (group B). In group A, all patients had more than 3 FA malformations and all 5 boys had cryptorchidism associated with microphallus in 4. All patients had heights and plasma insulin-like growth factor I < -3SD. Final height was reached in 15 patients and was < or = -2SD in 12 of them, all but 3 were born small for gestational age and/or given norethandrolone and/or corticosteroids. Gonadal function was abnormal in 5/7 boys and 4/5 girls evaluated at pubertal age. The plasma concentrations were low in 4/9 for antimüllerian hormone and in 3/9 for inhibin B, 3 of them had been given bone marrow transplantation.

CONCLUSIONS

PSIS can be part of a severe FA phenotype. It seems to occur mainly in boys, with more than 3 malformations, microphallus and cryptorchidism. This phenotype is associated with normal blood counts, defining a new clinical subgroup of patients.

Growth hormone treatment and cancer risk

Increasing numbers of children receive growth hormone (GH) to treat a range of growth disorders, including those rendered GH deficient (GHD) by tumors or their treatment. Young persons with persistent growth hormone deficiency (GHD) and adults with severe GHD are also eligible to receive GH treatment. As in vitro and in vivo studies and epidemiologic observations provide some evidence that the GH--insulin like growth factor-I (IGF-I) axis is associated with tumorigenesis, it is important to assess, in practice, the incidence of tumors related to GH treatment. Reassuringly, surveillance studies in large cohorts of children and in smaller cohorts of adults indicate that GH is not associated with an increased incidence of tumor occurrence or recurrence. Nevertheless, all children who have received GH, in particular cancer survivors and those receiving GH in adulthood, should be in surveillance programs to assess whether an increased rate od late-onset and rare tumours may occur.

Thymic hyperplasia in a child treated with growth hormone

OBJECTIVE

To report a case of thymic hyperplasia diagnosed three months after initiation of recombinant human growth hormone (GH) for the treatment of GH deficiency.

DESIGN

Retrospective chart review was conducted to evaluate the temporal relationship between treatment with GH and thymic enlargement in a 7-year-old girl who had a history of embryonal rhabdomyosarcoma of the nasopharynx diagnosed at the age of 3 years.

RESULTS

The diagnosis of GH deficiency was made based on clinical and auxological criteria, an insufficient response to clonidine-arginine stimulation testing (peak GH level of 4.8 microg/L) and low insulin-like growth factor 1 (IGF-1) level (30 ng/mL, -2.7 SD). The patient was started on GH at a dose of 0.3mg/kg/week. At the initiation of treatment with GH, the baseline growth velocity was 0.8 cm/year (-6.0 SD) and height was 112.5 cm (-1.7 SD). After three months of treatment with GH, her height increased by 4.2 cm (from -1.7 to -1.2 SD), and the IGF-1 level from -2.7 SD to -1.1 SD. A chest CT performed at that time for recurrence surveillance showed 89% increase in thymic volume relative to previous scan before treatment with growth hormone. A thoracoscopic biopsy of the thymus was performed and revealed hyperplasia with normal thymic architecture without evidence of malignancy.

CONCLUSIONS

The timing of the development of thymic hyperplasia, along with data from in vitro and in vivo animal studies showing that GH and IGF-1 can directly stimulate growth of the thymus, suggests that GH contributed to the development of thymic hyperplasia in this patient.

GH/IGF e neoplasia: o que há de novo nesta associação

Estudos in vitro e em animais sugerem que os membros do sistema insulin-like growth factors (IGFs), incluindo IGF-I, IGF-II, receptores de IGF-I e IGF-II (IGF-IR e IGF-IIR), e as IGF-binding proteins (IGFBPs) podem ter um importante envolvimento no desenvolvimento e na progressão de neoplasias. Mais especificamente, as IGFs promovem a progressão do ciclo celular e inibem a apoptose tanto por ação direta com outros fatores de crescimento como por ação indireta interagindo com outros sistemas moleculares intracelulares envolvidos na promoção e/ou progressão do câncer. Além disso, inúmeros estudos epidemiológicos têm sugerido que concentrações elevadas das IGFs, independente das alterações nas IGFBPs, podem estar associadas a um aumento no risco de desenvolver determinadas neoplasias. Esta revisão tem como objetivo apresentar o envolvimento do sistema IGF na regulação tumoral, os principais estudos epidemiológicos realizados e o risco de desenvolvimento de neoplasia em pacientes (com ou sem história pessoal de neoplasia prévia) que receberam hormônio de crescimento (rhGH). É importante salientar que o uso clínico de rhGH, nas indicações aprovadas internacionalmente, é seguro e não existem evidências, até o momento, da associação com o desenvolvimento de neoplasias.

Growth hormone treatment: cancer risk

There have been concerns that growth hormone (GH) therapy may be associated with an increased risk of cancer. Although data are limited and conflicting, one recent report on cancer risk in individuals with no cancer history or risk factors for cancer who were treated with pituitary GH demonstrated a small increased risk of colon cancer and deaths from colon cancer and Hodgkin disease. The data from cancer survivors have consistently shown no increased risk of recurrence of the primary tumor in survivors of all tumor types who are treated with GH. One recent study did show a small increased risk of second solid tumors in survivors previously treated with GH. Limited data suggest that GH therapy is not associated with excess cancer risk in individuals with Langerhans cell histiocytosis and neurofibromatosis type 1. Overall, the clinical data are reassuring, but continued surveillance is mandatory.

Growth hormone therapy

Growth hormone (GH) therapy has revolutionized treatment of children with growth hormone deficiency (GHD). Improved height outcome with final height in the target height range has been achieved in these children. Identification of Creutzfeldt-Jakob disease, a deadly prion mediated disorder, in recipients of pituitary GH accelerated the transition from pituitary derived GH to recombinant GH. Once daily subcutaneous administration of the freeze-dried preparation at evening is the recommended mode of GH therapy. Studies have led to use of higher dose of GH for improving height outcome (0.33 mg/kg/week or 0.14 IU/kg/day) albeit at a significantly high cost. Growth velocity increases from 3-4 cm/year before therapy to 10-12 cm/year during the first two years of therapy and is maintained at 7-8 cm/year after a period of two years. Close follow-up with regular clinical and laboratory monitoring is essential for achieving a desirable height outcome. A theoretical unlimited supply has led to wide spread use of GH in a variety of disorders other than GHD. Initially started in children with Turner syndrome, GH has now been used in chronic renal failure, idiopathic short stature and intrauterine growth restriction besides a wide array of newly emerging indications.

Hormones and Supplements: Do They Work?: Use of Growth Hormone for Prevention or Treatment of Effects of Aging

Decreases in growth hormone (GH) and insulin-like growth factor-I, estrogen deficiency in women, diminished testosterone in men, and loss of lean body mass, increased fat, and other changes consistent with hormone deficiencies occur during aging. Treatment of nonelderly GH-deficient adults with recombinant human GH (rhGH) improves body composition, muscle strength, physical function, and bone density, and reduces blood cholesterol and cardiovascular disease risk, but is often accompanied by carpal tunnel syndrome, peripheral edema, joint pain and swelling, gynecomastia, glucose intolerance, and possibly increased cancer risk. Reports that rhGH augments lean body mass and reduces body fat in aged individuals increased use of rhGH to delay aging effects. However, clinically significant functional benefits, prolongation of youth, and life extension have not been demonstrated. Moreover, marketing of rhGH and other hormone supplements largely ignores adverse effects. Until more research has better defined the risk/benefit relationships, treatment of elderly individuals with rhGH should be confined to controlled research studies.

Pituitary stalk thickening and primary central nervous system lymphoma

We report a 14-year-old girl in whom a diagnosis of primary central nervous system lymphoma was confirmed while receiving growth hormone (GH) for GH deficiency, detected after presenting with short stature. MRI revealed an enhancing and thickened pituitary stalk with absence of the normal bright signal in the posterior pituitary. Regular MRI surveillance detected progression of the neurohypophyseal changes 13 months into GH treatment. Biopsy confirmed this to be B-cell large cell lymphoma. This case highlights the diagnostic and management challenges inherent in treating such children.

Can GH induce chromosome breaks or microsatellite instability in GH-deficient children?

The role of GH in carcinogenesis is unclear. We studied the effect of recombinant human GH (rhGH) in vitro on chromosomal and genomic instability. Thirteen children, aged 9.57 +/- 1.08 yr (mean +/- SEM), with complete (no.=5) or partial (no.=8) GH deficiency were evaluated before and during GH treatment. We examined the incidence of chromosome and chromatid breaks, and microsatellite instability after in vitro addition of two different doses of rhGH to peripheral blood lymphocytes obtained from the patients. No differences were observed between the samples of GH-deficient children before and after GH therapy as regards the percentage of chromosome and chromatids breaks, and in microsatellite instability. Our data show that in vitro addition of rhGH does not induce chromosomal and/or genomic instability in cultured lymphocytes.

Advances in Growth Hormone Therapy: A New Registry Tool

Growth hormone (GH) deficiency is a rare condition, and physicians may lack clinical experience of its treatment. Despite evidence for the efficacy and tolerability of GH therapy, a substantial proportion of patients remain untreated. Registries and other large-scale databases are an important tool for expanding the evidence base for GH treatment. Since the mid-1980s, registries have provided data on important aspects of the safety and efficacy of GH treatment. Registries have also allowed pooling of data from patients with rare conditions that could otherwise not be recruited in sufficient numbers for clinical trials. Importantly for patients and their relatives, use of registry data has allowed the development of prediction models that indicate the likely outcomes of treatment. MEGHA (Metabolic Endocrinology and Growth Hormone Assessment) is a recently developed, observational database with a number of features not found in existing registries, including its use as a day-to-day clinical management tool, the ability to create individual sub-studies, direct comparison of personal data against the full database, and a particular focus on the transition from childhood to adulthood. This creative registry is a promising instrument for further research into GH-related disorders that will improve GH therapy and thus provide benefits for patients.

Cancer Risk Following Growth Hormone Use in Childhood

The therapeutic use of growth hormone (GH) has caused concern, as it is anabolic and mitogenic, and its effector hormone, insulin-like growth factor (IGF)-I is anti-apoptotic. As both hormones can cause proliferation of normal and malignant cells, the possibility that GH therapy may induce cancer, increase the risk of tumour recurrence in those previously treated for a malignancy, or increase the risk of cancer in those with a predisposition, has resulted in concerns over its use. There are theoretical and epidemiological reasons that suggest GH and IGF-I may be important in tumour formation and proliferation. Malignant tumours have been induced in animals exposed to supraphysiological doses of GH, whereas hypophysectomy appears to protect animals from carcinogen-induced neoplasms. In vitro, proliferation and transformation of normal haemopoetic and leukaemic cells occurs with supraphysiological doses of GH, but not with physiological levels. IGF, IGF binding proteins (IGFBP) and IGFBP proteases influence the proliferation of cancer cells in vitro; however, GH is probably not involved in this process. Epidemiological studies have suggested an association between levels of IGF-I and cancer, and an inverse relationship between IGFBP-3 and cancer; however, these associations have been inconsistent. A number of studies have been undertaken to determine the risk of the development of cancer in children treated with GH, either de novo, or the recurrence of cancer in those previously treated for a malignancy. Despite early concerns following a report of a cluster of cases of leukaemia in recipients of GH, there appears to be no increased risk for the development of leukaemia in those treated with GH unless there is an underlying predisposition. Even in children with a primary diagnosis of cancer, subsequent GH use does not appear to increase the risk of tumour recurrence. However, a recent follow-up of pituitary GH recipients has suggested an increase in colorectal cancer. In addition, follow-up of oncology patients has suggested an increase in second neoplasms in those who also received GH therapy. These studies emphasise the importance of continued surveillance both internationally with established databases and also nationally through single-centre studies.

Aplastic anemia during growth hormone (GH) treatment in a girl with idiopathic GH-deficiency

We report a 12-year-old girl with aplastic anemia accompanied by chromosome 8 trisomy during growth hormone (GH) therapy. When she was six years old she was diagnosed as idiopathic isolated GH deficiency, and GH therapy (0.175 mg/kg/week) was initiated. At the age 12, she began to exhibit petechiae in both lower limbs. Platelet count was 11,000/microL; serum hemoglobin level 11.8 gr/mL; white blood cell count 3,400/microL, with 37% neutrophils, 58% lymphocytes, 4% monocytes and 1% basophils. Bone marrow examination showed that total nucleated cell count and megakaryocyte were 17,000/microL and 0/microL, respectively, suggesting low formation. In addition, 13% of bone marrow cells contained the 3 signals of chromosome 8 marker (trisomy 8). She was diagnosed as aplastic anemia accompanied with chromosome 8 trisomy. GH therapy was stopped immediately, and simultaneous administration of methylprednisolone and anti-thymocyte globulin was initiated. Platelet count improved with treatment, and the 3-signal chromosome 8 abnormality disappeared from the bone marrow cells. The fact that a hematological adverse effect other than leukemia exists in conjunction with GH therapy warrants further investigation into possible hematological changes occurring during or after GH therapy.