Bone Morbidity and Recovery in Children With Acute Lymphoblastic Leukemia: Results of a Six-Year Prospective Cohort Study

Prevalence of Osteopathologies in Children and Adolescents After Diagnosis of Acute Lymphoblastic Leukemia

Background: Impaired bone health is a late effect of childhood malignancies which can be difficult to detect in juvenile survivors. It may, however, lead to compromised quality of life, or even permanent disability later in life due to osteoporosis, pain or fractures if left untreated. Acute lymphoblastic leukemia (ALL) is the most frequent childhood malignancy with an over 85% five-year survival. ALL and its treatment cause bone alterations in adults, but little information on the bone health status in juvenile survivors is available. Objective: To report data on skeletal late effects in juvenile survivors of childhood ALL based on a comprehensive assessment of bone health and to assess the influence of a vitamin D deficiency on bone health in this cohort. Methods: In a single center cross sectional study 128 pediatric patients (11.9 ± 4.76 years) with a mean follow up of 5.88 ± 3.75 years after diagnosis of ALL were recruited. The bone health status of the survivors was assessed based on clinical examination, review of medical records, biochemical and radiographic analyses, by clinical experts. A score which utilized 8 different parameters was formed and used to assess the effect of a vitamin D deficiency on bone health. Results: In this cohort, 18% of survivors displayed overt osteopathologies as defined by clinical expert assessment. Impaired bone health, defined by at least one pathological screening parameter, was detected in 77%. Despite recommendations for adequate vitamin D supplementation, 15% displayed a vitamin D deficiency associated with hyperparathyroidism. The applied score identified survivors with osteopathologies with high sensitivity and specificity. The median score did not differ between patients without and with severe vitamin D deficiency. Conclusion: Our findings suggest that impaired bone health and osteopathologies are common skeletal late effects following treatment of childhood ALL. Major contributing factors are BMT, irradiation and older age at diagnosis. Vitamin D deficiency likely accounts for hyperparathyroidism in some patients but does not seem to further affect bone health in this cohort. Survivors of ALL need thorough surveillance to investigate bone health, since bone morbidity is common and still poorly understood. Early detection and appropriate intervention may improve bone health.

Glucocorticoid-induced osteoporosis update

PURPOSE OF REVIEW

Steroid-induced osteoporosis or glucocorticoid-induced osteoporosis (GIOP) is a common form of secondary osteoporosis and is a cause of increased morbidity and mortality. The pathogenesis of GIOP includes decreased bone formation and increased bone resorption. Clinicians can rely on several effective medications for the treatment and prevention of GIOP, including antiresorptive drugs (i.e. bisphosphonates) and bone anabolic drugs (i.e. teriparatide).

RECENT FINDINGS

Recent studies have further highlighted that GIOP is a major public health concern and have provided new insights on the pathogenesis of GIOP, in particular, the dose-dependent effects of glucocorticoids on bone. New evidence on the real-world effectiveness of established GIOP therapies have been recently published as well as the results of the 24-months denosumab randomized controlled trial in GIOP.

SUMMARY

GIOP and fragility fractures are important adverse events related to the long-term use of glucocorticoids. Recent studies have provided additional data on the epidemiology and pathogenesis of GIOP and on the efficacy and effectiveness of GIOP therapies.

A Contemporary View of the Definition and Diagnosis of Osteoporosis in Children and Adolescents

The last 2 decades have seen growing recognition of the need to appropriately identify and treat children with osteoporotic fractures. This focus stems from important advances in our understanding of the genetic basis of bone fragility, the natural history and predictors of fractures in chronic conditions, the use of bone-active medications in children, and the inclusion of bone health screening into clinical guidelines for high-risk populations. Given the historic focus on bone densitometry in this setting, the International Society for Clinical Densitometry published revised criteria in 2013 to define osteoporosis in the young, oriented towards prevention of overdiagnosis given the high frequency of extremity fractures during the growing years. This definition has been successful in avoiding an inappropriate diagnosis of osteoporosis in healthy children who sustain long bone fractures during play. However, its emphasis on the number of long bone fractures plus a concomitant bone mineral density (BMD) threshold ≤ -2.0, without consideration for long bone fracture characteristics (eg, skeletal site, radiographic features) or the clinical context (eg, known fracture risk in serious illnesses or physical-radiographic stigmata of osteoporosis), inappropriately misses clinically relevant bone fragility in some children. In this perspective, we propose a new approach to the definition and diagnosis of osteoporosis in children, one that balances the role of BMD in the pediatric fracture assessment with other important clinical features, including fracture characteristics, the clinical context and, where appropriate, the need to define the underlying genetic etiology as far as possible.

Bone morbidity in pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL), currently the most common pediatric leukemia, has a high curability rate of up to 90%. Endocrine disorders are highly prevalent in children with ALL, and skeletal morbidity is a major issue induced by multiple factors associated with ALL. Leukemia itself is a predominant risk factor for decreased bone formation, and major bone destruction occurs secondary to chemotherapeutic agents. Glucocorticoids are cornerstone drugs used throughout the course of ALL treatment that exert significant effects on demineralization and osteoclastogenesis. After completion of treatment, ALL survivors are prone to multiple hormone deficiencies that eventually affect bone mineral accrual. Dual-energy X-ray absorptiometry, the most widely used method of measuring bone mineral density, is used to determine the presence of childhood osteoporosis and vertebral fracture. Supplementation with calcium and vitamin D, administration of pyrophosphate analogues, and promotion of mobility and exercise are effective options to prevent further bone resorption and fracture incidence. This review focuses on addressing bone morbidity after pediatric ALL treatment and provides an overview of bone pathology based on skeletal outcomes to increase awareness among pediatric hemato-oncologists and endocrinologists.

Glucocorticoid-Induced Osteoporosis: Why Kids Are Different

Glucocorticoids (GC) are an important risk factor for bone fragility in children with serious illnesses, largely due to their direct adverse effects on skeletal metabolism. To better appreciate the natural history of fractures in this setting, over a decade ago the Canadian STeroid-associated Osteoporosis in the Pediatric Population ("STOPP") Consortium launched a 6 year, multi-center observational cohort study in GC-treated children. This study unveiled numerous key clinical-biological principles about GC-induced osteoporosis (GIO), many of which are unique to the growing skeleton. This was important, because most GIO recommendations to date have been guided by adult studies, and therefore do not acknowledge the pediatric-specific principles that inform monitoring, diagnosis and treatment strategies in the young. Some of the most informative observations from the STOPP study were that vertebral fractures are the hallmark of pediatric GIO, they occur early in the GC treatment course, and they are frequently asymptomatic (thereby undetected in the absence of routine monitoring). At the same time, some children have the unique, growth-mediated ability to restore normal vertebral body dimensions following vertebral fractures. This is an important index of recovery, since spontaneous vertebral body reshaping may preclude the need for osteoporosis therapy. Furthermore, we now better understand that children with poor growth, older children with less residual growth potential, and children with ongoing bone health threats have less potential for vertebral body reshaping following spine fractures, which can result in permanent vertebral deformity if treatment is not initiated in a timely fashion. Therefore, pediatric GIO management is now predicated upon early identification of vertebral fractures in those at risk, and timely intervention when there is limited potential for spontaneous recovery. A single, low-trauma long bone fracture can also signal an osteoporotic event, and a need for treatment. Intravenous bisphosphonates are currently the recommended therapy for pediatric GC-induced bone fragility, typically prescribed to children with limited potential for medication-unassisted recovery. It is recognized, however, that even early identification of bone fragility, combined with timely introduction of intravenous bisphosphonate therapy, may not completely rescue the osteoporosis in those with the most aggressive forms, opening the door to novel strategies.

Systematic review of the effects of bisphosphonates on bone density and fracture incidence in childhood acute lymphoblastic leukaemia

Skeletal fragility is a common complication of childhood acute lymphoblastic leukaemia (ALL) but the impact of bisphosphonate therapy on bone mass and fracture is unclear. We aim to conduct a systematic review to evaluate the effects of bisphosphonates on bone mineral density (BMD) and fracture incidence in children with ALL.

METHODS

EMBASE, Medline and the Cochrane Library were thoroughly searched by two researchers. Inclusion criteria was any child under the age of 18 years with a diagnosis of ALL, who had received any bisphosphonate treatment and had serial measurements of bone density performed thereafter. All primary research studies of any study design, excluding case reports, were included.

RESULTS

Ten full text papers were identified with two exclusively meeting the inclusion criteria. Both studies administered bisphosphonates to children receiving maintenance chemotherapy for varying durations. Bone density was assessed at regular intervals by dual x-ray absorptiometry (DXA). The majority of participants had an improvement in bone density at the end of each study. However, no size adjustment of DXA data was performed. Limited information on fracture occurrence was provided by one study but did not include routine screening for vertebral fractures.

CONCLUSIONS

This systematic review identified that there is insufficient evidence to support routine use of prophylactic bisphosphonate therapy in childhood ALL for prevention of fracture and improvement of bone mass. Future well-designed clinical trials in those at highest risk of fractures in ALL are now needed.

Bone density in children: what are we measuring?

The measurement of bone density is a frequent request in the assessment of children with concerns about bone health due to chronic disease or recurrent fractures. Dual energy X-ray absorptiometry (DXA) remains the recommended modality and is widely available. However, the interpretation and reporting of results in growing individuals needs to be undertaken by individuals who are familiar with scanning children and the potential pitfalls.

The Utility of DXA Assessment at the Forearm, Proximal Femur, and Lateral Distal Femur, and Vertebral Fracture Assessment in the Pediatric Population: 2019 ISCD Official Position

Dual-energy X-ray absorptiometry (DXA) is widely used in the evaluation of bone fragility in children. Previous recommendations emphasized total body less head and lumbar spine DXA scans for clinical bone health assessment. However, these scan sites may not be possible or optimal for all groups of children with conditions that threaten bone health. The utility of DXA scans of the proximal femur, forearm, and radius were evaluated for adequacy of reference data, precision, ability of predict fracture, and applicability to all, or select groups of children. In addition, the strengths and limitations of vertebral fracture assessment by DXA were evaluated. The new Pediatric Positions provide guidelines on the use of these additional measures in the assessment of skeletal health in children.

Severity of reduced bone mineral density and risk of fractures in long-term survivors of childhood leukemia and lymphoma undergoing guideline-recommended surveillance for bone health

BACKGROUND

Survivors of childhood leukemia/lymphoma are at increased risk for reduced bone mineral density (BMD). The authors sought to determine the frequency of reduced BMD detected by off-therapy surveillance, factors associated with reduced BMD, and the association of reduced BMD with fractures.

METHODS

This cross-sectional study included childhood leukemia/lymphoma survivors attending 2 survivorship clinics who received guideline-recommended BMD surveillance ≥2 years post-therapy with dual-energy x-ray absorptiometry (from January 1, 2004 to August 31, 2016). Lumbar spine BMD z-scores were height-for-age-adjusted. Low and very low BMD were >1 SD and >2 SDs below norms, respectively. Treatment, chronic conditions, and fractures were abstracted from medical records. Logistic regression was used to examine the association of low BMD with patient/treatment factors and fractures.

RESULTS

In total, 542 patients (51.5% female) with a mean age of 15.5 years (range, 4.4-52.2 years) who were 6 years post-therapy (range, 2.0-35.1 years) were evaluated, including 116 who reported post-therapy fractures. Lumbar spine low BMD was identified in 17.2% of survivors, and very low BMD was identified in 3.5% of survivors, but frequencies varied considerably between subgroups; 10.8% of survivors aged 15 to 19 years at diagnosis had very low BMD. In multivariable analyses, older age at diagnosis, white race, and being underweight were significantly associated with low BMD. Survivors with low BMD had greater odds of nondigit fractures (odds ratio, 2.2; 95% CI, 1.3-3.7) and specifically long-bone fractures (odds ratio, 2.7; 95% CI, 1.5-4.7).

CONCLUSIONS

In this study of childhood leukemia/lymphoma survivors undergoing guideline-recommended dual-energy x-ray absorptiometry surveillance, patients who were older at diagnosis, white, and underweight were at the highest risk for lumbar spine low BMD. Low BMD was associated with a greater risk of fractures, emphasizing the clinical importance of surveillance.

The Radiology of Osteoporotic Vertebral Fractures Revisited

Until recently there has been little evidence available to validate any method by which to make an accurate diagnosis of an osteoporotic vertebral fractures (OVFs) from plain radiographs. In part this reflects a lack of a completely satisfactory "gold standard," but primarily it relates to the absence of well-designed prospective studies in this context. Historically, OVFs were recognized by evidence of macroscopic structural failure in vertebrae using the criteria applied elsewhere in the skeleton. This comprised altered alignment, fragmentation, cortical disruptions, and breaks, among other changes. However, these morphological criteria were replaced by vertebral morphometry, referring to the use of quantitative or quasi-quantitative measurement tools for fracture diagnosis. Vertebral morphometry emerged as an understanding of and treatment for osteoporosis evolved, mainly in response to the need for expeditious assessments of large numbers of spine images for epidemiological and pharmaceutical purposes. Although most of the descriptions of such morphometric tools have stressed that they were not to be applied to clinical diagnosis with respect to individual patients, this constraint has been widely disregarded. Here we review the major attempts to develop a diagnostic strategy for OVF and describe their characteristics in adults and children. Recent evidence suggests that morphometric (quantitative; ie, based on measurement of dimensions and shape description) criteria are inferior to morphologic (qualitative; ie, based on structural integrity) vertebral damage assessment in identifying people with low bone density and at an increased risk of future fracture. Thus there is now an evidentiary basis for suggesting that morphological assessment is the preferred strategy for use in diagnosing OVF from radiographs. © 2019 American Society for Bone and Mineral Research.

The skeletal impact of cancer therapies

Both cancer and therapies used in the treatment of cancer can have significant deleterious effects on the skeleton, increasing the risks for both bone loss and fracture development. While advancements in cancer therapies have resulted in enhanced cancer survivorship for patients with many types of malignancies, it is increasingly recognized that efforts to reduce bone loss and limit fractures must be considered for nearly all patients undergoing cancer therapy in order to diminish the anticipated future skeletal consequences. To date, most studies examining the impact of cancer therapies on skeletal outcomes have focused on endocrine-associated cancers of the breast and prostate, with more recent advances in our understanding of bone loss and fracture risk in other malignancies. Pharmacologic efforts to limit the adverse effects of cancer therapies on bone have nearly universally employed anti-resorptive approaches, although studies have frequently relied on surrogate outcomes such as changes in bone mineral density or bone turnover markers, rather than on fractures or other skeletal-related events, as primary study endpoints. Compounding current deficiencies for the provision of optimal care is the recognition that despite clearly written and straightforward society-based guidelines, vulnerable eligible patients are very often neither identified nor provided with appropriate treatments to limit the skeletal impact of their cancer therapies.

Impact of Vertebral Fractures and Glucocorticoid Exposure on Height Deficits in Children During Treatment of Leukemia

OBJECTIVE

To assess the effect of vertebral fractures (VF) and glucocorticoid (GC) exposure on height deficits in children during treatment of acute lymphoblastic leukemia (ALL).

METHODS

Children with ALL treated without cranial radiation therapy (n = 160; median age, 5.1 years; 58.1% male) were followed prospectively for 6 years. Spinal deformity index (SDI) was used to quantify VF status.

RESULTS

Baseline height z score ± SD was 0.3 ± 1.2. It fell by 0.5 ± 0.4 in the first 6 months for boys and by 0.4 ± 0.4 in the first 12 months for girls (P < 0.01 for both) and then subsequently recovered. The prevalence of VF peaked at 1 year (17.6%). Among those with VF, median SDI rose from 2 [interquartile range (IQR): 1, 7] at baseline to 8 (IQR: 1, 8) at 1 year. A mixed model for repeated measures showed that height z score declined by 0.13 (95% CI: 0.02 to 0.24; P = 0.02) for each 5-unit increase in SDI during the previous 12 months. Every 10 mg/m2 increase in average daily GC dose (prednisone equivalent) in the previous 12 months was associated with a height z score decrement of 0.26 (95% CI: 0.20 to 0.32; P < 0.01).

CONCLUSIONS

GC likely plays a major role in the observed height decline during therapy for ALL. Because only a minority of children had VF, fractures could not have contributed significantly to the height deficit in the entire cohort but may have been important among the subset with VF.

Skeletal Morbidity in Children and Adolescents during and following Cancer Therapy

Skeletal abnormalities are common in children and adolescents diagnosed and treated for a malignancy. The spectrum ranges from mild pain to debilitating osteonecrosis and fractures. In this review, we summarize the impact of cancer therapy on the developing skeleton, provide an update on therapeutic strategies for prevention and treatment, and discuss the most recent advances in musculoskeletal research. Early recognition of skeletal abnormalities and strategies to optimize bone health are essential to prevent long-term skeletal sequelae and diminished quality of life in childhood cancer survivors.

New Insights Into Monogenic Causes of Osteoporosis

Osteoporosis, characterized by deteriorated bone microarchitecture and low bone mineral density, is a chronic skeletal disease with high worldwide prevalence. Osteoporosis related to aging is the most common form and causes significant morbidity and mortality. Rare, monogenic forms of osteoporosis have their onset usually in childhood or young adulthood and have specific phenotypic features and clinical course depending on the underlying cause. The most common form is osteogenesis imperfecta linked to mutations in COL1A1 and COL1A2, the two genes encoding type I collagen. However, in the past years, remarkable advancements in bone research have expanded our understanding of the intricacies behind bone metabolism and identified novel molecular mechanisms contributing to skeletal health and disease. Especially high-throughput sequencing techniques have made family-based studies an efficient way to identify single genes causative of rare monogenic forms of osteoporosis and these have yielded several novel genes that encode proteins partaking in type I collagen modification or regulating bone cell function directly. New forms of monogenic osteoporosis, such as autosomal dominant osteoporosis caused by WNT1 mutations or X-linked osteoporosis due to PLS3 mutations, have revealed previously unidentified bone-regulating proteins and clarified specific roles of bone cells, expanded our understanding of possible inheritance mechanisms and paces of disease progression, and highlighted the potential of monogenic bone diseases to extend beyond the skeletal tissue. The novel gene discoveries have introduced new challenges to the classification and diagnosis of monogenic osteoporosis, but also provided promising new molecular targets for development of pharmacotherapies. In this article we give an overview of the recent discoveries in the area of monogenic forms of osteoporosis, describing the key cellular mechanisms leading to skeletal fragility, the major recent research findings and the essential challenges and avenues in future diagnostics and treatments.