Response assessment by positron emission tomography-computed tomography as compared with contrast-enhanced computed tomography in childhood Hodgkin lymphoma can reduce the need for radiotherapy in low- and middle-income countries.

INTRODUCTION: The InPOG-HL-15-01, a multicentric prospective study, used a risk-stratified and response-based approach with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) backbone to treat children and adolescents with newly diagnosed Hodgkin lymphoma (HL) and reduce the use of radiation therapy (RT). Children/adolescents with bulky disease or inadequate response at early response assessment (ERA) after two cycles of chemotherapy were assigned to receive RT. For ERA, positron emission tomography computed tomography (PET-CT) was recommended but not mandatory in view of limited access. This study aimed to compare the impact of using contrast-enhanced computed tomography (CECT) and PET-CT on treatment decisions and outcomes. METHODOLOGY: 396 patients were enrolled and 382 had an ERA at the assigned time point. Satisfactory response was defined as Deauville score 3 or less for patients undergoing PET-CT and complete response (CR)/very good partial response (VGPR) for patients undergoing CECT. Outcomes of interest incorporate 5 year event-free survival (EFS), EFS including abandonment (EFSa), and overall survival (OS). RESULTS: At ERA, satisfactory response was documented in 277 out of 382 (72.5%) participants and this was significantly higher in PET-CT (151 out of 186, 81.2%) as compared with CECT-based assessments (126 out of 196, 64.3%) respectively (p value < .001). Amongst the 203 patients with nonbulky disease (wherein the indication for RT was entirely dependent on ERA), 96 out of 114 (84.2%) and 61 out of 89 (68.5%) patients achieved a satisfactory response according to the PET-CT and CECT (p value = .008) respectively and hence a lesser proportion of patients in the PET-CT arm received RT. Despite a lower usage of RT the 5 year OS of both groups, ERA based on CECT (91.8%) versus PET-CT (94.1%) was comparable (p value = .391) and so was the 5 year EFS (86.7 vs. 85.5%, p value = .724). CONCLUSION: Use of PET-CT as the modality for ERA is more likely to indicate a satisfactory response as compared with CECT and thereby decreases the need for RT in response-based treatment algorithm for HL-afflicted children. The reduction in the application of RT did not impact the overall outcome and plausibly would lower the risk of delayed toxic effects.

Sustainable care for children with cancer: a Lancet Oncology Commission.

We estimate that there will be 13·7 million new cases of childhood cancer globally between 2020 and 2050. At current levels of health system performance (including access and referral), 6·1 million (44·9%) of these children will be undiagnosed. Between 2020 and 2050, 11·1 million children will die from cancer if no additional investments are made to improve access to health-care services or childhood cancer treatment. Of this total, 9·3 million children (84·1%) will be in low-income and lower-middle-income countries. This burden could be vastly reduced with new funding to scale up cost-effective interventions. Simultaneous comprehensive scale-up of interventions could avert 6·2 million deaths in children with cancer in this period, more than half (56·1%) of the total number of deaths otherwise projected. Taking excess mortality risk into consideration, this reduction in the number of deaths is projected to produce a gain of 318 million life-years. In addition, the global lifetime productivity gains of US$2580 billion in 2020-50 would be four times greater than the cumulative treatment costs of $594 billion, producing a net benefit of $1986 billion on the global investment: a net return of $3 for every $1 invested. In sum, the burden of childhood cancer, which has been grossly underestimated in the past, can be effectively diminished to realise massive health and economic benefits and to avert millions of needless deaths.

A framework to develop adapted treatment regimens to manage pediatric cancer in low- and middle-income countries: The Pediatric Oncology in Developing Countries (PODC) Committee of the International Pediatric Oncology Society (SIOP).

Many children with cancer in low- and middle-income countries are treated in hospitals lacking key infrastructure, including diagnostic capabilities, imaging modalities, treatment components, supportive care, and personnel. Childhood cancer treatment regimens adapted to local conditions provide an opportunity to cure as many children as possible with the available resources, while working to improve services and supportive care. This paper from the Adapted Treatment Regimens Working Group of the Pediatric Oncology in Developing Countries committee of the International Society of Pediatric Oncology outlines the design, development, implementation, and evaluation of adapted regimens and specifies levels of services needed to deliver them.

A practical approach to reporting treatment abandonment in pediatric chronic conditions.

Treatment abandonment, the failure to complete therapy that is required for definitive disease control, frequently causes treatment failure for pediatric patients in low- and middle-income countries with chronic conditions, particularly cancer. Other forms of incomplete treatment affecting children in all settings, such as nonadherence and loss to follow-up, are often confused with treatment abandonment. Unclear definitions of incomplete treatment dramatically affect reported outcomes. To facilitate disease-specific and cross-sector analyses, we outline a practical approach to categorize forms of incomplete treatment, present distinct semantic categories with case examples and provide an algorithm that could be tailored to disease- and context-specific needs.

The contrasting age-incidence patterns of bone tumours in teenagers and young adults: Implications for aetiology.

Bone tumours comprise 0.2% of cancers overall but 5.7% in 15-24 year olds. To explore the relationship with adolescence we have analysed age-incidence patterns of bone tumours in a large national dataset. Data on incident cases of bone tumours in 0-84 year olds in England, 1979-2003, were extracted from national cancer registration data. Incidence rates per million person-years by 5-year age-group, sex, morphology and primary site were calculated and adjusted to the world standard population. Nine thousand one hundred forty-six cases were identified giving an overall age-standardized rate of 7.19 per million person-years. The distribution by morphology was: osteosarcoma, 34.2%; chondrosarcoma, 27.2%; Ewing sarcoma, 19.3%; other, 19.4%. The distribution varied by age. Ewing sarcoma was most common in 0-9 year olds, osteosarcoma in 10-29 year olds and chondrosarcoma in 30-84 year olds. 29.2% of all tumours occurred in 0-24 year olds. Highest incidence of osteosarcoma and Ewing sarcoma in females was in 10-14 year olds. In males, peak incidence occurred at 15-19 years and exceeded that in females. Chondrosarcoma incidence steadily increased with age. The proportions of Ewing sarcomas occurring in respective bones were consistent with those of the adult skeleton by weight. In osteosarcoma tumours of long bones of lower limb were markedly over-represented in the adolescent peak, being six times more than at any other site. Variation in incidence patterns with age and site suggests pubertal bone growth to be a key factor in osteosarcoma while different biological pathways could be relevant for Ewing sarcoma.

Comparative incidence patterns and trends of gonadal and extragonadal germ cell tumors in England, 1979 to 2003.

BACKGROUND: It is believed that gonadal and extragonadal germ cell tumors (GCTs) arise from primordial germ cells and may have similar etiopathogenesis. Unlike testicular GCTs, there has been limited comprehensive population-based analysis of ovarian and extragonadal GCTs. METHODS: All malignant GCTs and all central nervous system (CNS) GCTs with benign and uncertain behavior that were registered in England in the age group 0 to 84 years from 1979 to 2003 were included in the current study. Incidence rates were calculated and adjusted to the world standard population. RESULTS: There were 33,364 GCTs (92.5% testes, 3.9% ovary, 3.2% extragonadal) in individuals aged 0 to 84 years. The CNS was the most common extragonadal site. An initial peak in incidence at ages 0 to 4 years of nongerminomas was observed at all sites except ovary. Second incidence peaks between ages 10 to 39 years that were more marked among males also were observed at all sites. The ages at these incidence peaks varied by site and were 10 to 14 years (CNS), 15 to 19 years (ovary), 25 to 29 years (other extragonadal sites), and 30 to 34 years (testes). A statistically significant increase in incidence over time was observed in germinomas (testes, CNS) and nongerminomas (testes, ovary). CONCLUSIONS: The age-incidence patterns observed suggested a common initiation of GCTs in embryonic/fetal life with variable rates of tumor progression as a result of subsequent events that may be site specific. The authors concluded that future genetic studies should consider GCTs from all sites to enable a better understanding of their etiology.

Cancer at ages 15-29 years: the contrasting incidence in India and England.

BACKGROUND: There has been a steady increase in published research from Europe and North America on the epidemiology of cancers in young people. There are limited data from the developing world. We contrast the incidence of cancer at ages 15-29 years in India and England. PROCEDURE: Malignant neoplasms in those aged 15-29 years registered during 2001-2003 in five urban population-based cancer registries (PBCRs) of India and in eight PBCRs in England were included. Site-based classification was used. Age-standardized incidence rates were expressed per 100,000 person years. RESULTS: In India, 4,864 (5.8%) of 84,450 cases and in England, 8,137 (1.2%) of 65,6752 cancer cases occurred in those aged 15-29 years. For this age group, the incidence rate for males and females in India were 12.91 and 14.19, and in England were 27.75 and 28.88, respectively. In males aged 15-29 years, the three most common cancers in India were leukemia, lymphoma, and central nervous system tumors and in England were cancers of male genital organs, lymphoma, and leukemia. Cancers of female genital organs, breast, and leukemia were most common in females in India and cancers of female genital organs, lymphoma, and melanoma in England. For cancers of mouth, stomach, and gall bladder, the incidence was higher in India. CONCLUSION: Incidence of cancer at ages 15-29 years in England is higher at most sites than in India. Variation in environmental exposures between the two countries might be an explanation. Under-ascertainment of cases and gender bias in seeking healthcare may also influence reported incidence rates in India.

The Global Impact of COVID-19 on Childhood Cancer Outcomes and Care Delivery - A Systematic Review.

Background: Childhood cancer represents a leading cause of death and disease burden in high income countries (HICs) and low-and-middle income countries (LMICs). It is postulated that the current COVID-19 pandemic has hampered global development of pediatric oncology care programs. This systematic review aimed to comprehensively review the global impact of COVID-19 on childhood cancer clinical outcomes and care delivery. Methods: A systematic search was conducted on PubMed, Embase, Medline, and the African Medical Index from inception to November 3, 2021 following PRISMA guidelines. A manual search was performed to identify additional relevant studies. Articles were selected based on predetermined eligibility criteria. Findings: The majority of studies reported patients with cancer and COVID-19 presenting as asymptomatic (HICs: 33.7%, LMICs: 22.0%) or with primary manifestations of fever (HICs: 36.1%, LMICs: 51.4%) and respiratory symptoms (HICs: 29.6%, LMICs: 11.7%). LMICs also reported a high frequency of patients presenting with cough (23.6%) and gastrointestinal symptoms (10.6%). The majority of patients were generally noted to have a good prognosis; however the crude mortality rate was higher in LMICs when compared to HICs (8.0% vs 1.8%). Moreover, the pandemic has resulted in delays and interruptions to cancer therapies and delays in childhood cancer diagnoses in both HICs and LMICs. However, these findings were disproportionately reported in LMICs, with significant staff shortages, supply chain disruptions, and limited access to cancer therapies for patients. Conclusions: The COVID-19 pandemic has resulted in delays and interruptions to childhood cancer therapies and delays in childhood cancer diagnoses, and disproportionately so within LMICs. This review provides lessons learned for future system-wide disruptions to care, as well as provides key points for moving forward better with care through the remainder of this pandemic. Systematic Review Registration: CRD42021266758, https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=266758.

Utilizing Multilingual Methods and Rapid Analysis for Global Qualitative Research During a Pandemic.

Historically, qualitative research has complemented quantitative biologic and epidemiologic studies to provide a more complete understanding of pandemics. The COVID-19 pandemic has generated unique and novel challenges for qualitative researchers, who have embraced creative solutions including virtual focus groups and rapid analyses to continue their work. We present our experience conducting a multilingual global qualitative study of healthcare resilience among teams of pediatric oncology professionals during the COVID-19 pandemic. We provide an in-depth description of our methodology and an analysis of factors we believe contributed to our study's success including our use of technology, engagement of a large multilingual team, global partnerships, and framework-based rapid analysis. We hope these techniques may be useful to qualitative researchers conducting studies during the current pandemic, as well as for all pediatric oncology studies including multiple languages or geographically disparate subjects.

Relationship between height at diagnosis and bone tumours in young people: a meta-analysis.

OBJECTIVE: Some evidence exists that patients with osteosarcoma and Ewing sarcoma are taller than the general population. However, previous studies are under-powered, lack comprehensive data and show inconsistencies. METHODS: Relevant studies linking osteosarcoma and Ewing sarcoma with height at diagnosis were identified in two major online databases, Medline (1950 to 2009) and Embase (1980 to 2009). Outcomes in individual studies were reported as standard deviation (SD) scores or percentages of study population with height at diagnosis above the median of the reference population. We performed separate random-effects meta-analyses for each outcome and tumour type. RESULTS: 14 studies examined the height of patients with osteosarcoma or Ewing sarcoma. Meta-analyses on SD scores found patients with osteosarcoma were 0.260 SD (95% CI: 0.088-0.432) taller than the reference population (five studies). A meta-analysis on percentages found 62% (95% CI: 57%-67%) of patients were estimated to have a height above the median (six studies). Patients with Ewing sarcoma were 0.096 SD (95% CI 0.004-0.188) taller (four studies). Only one study reported the percentage of Ewing sarcoma patients with height above the median. CONCLUSION: The average height of patients with osteosarcoma, but not Ewing sarcoma, was significantly above the average height of the reference population by 2-3 centimetres. The observed differences indicate the involvement of pubertal longitudinal bone growth in osteosarcoma development while different biological pathways could be relevant for Ewing sarcoma.

Assessing the impact of paediatric oncology publications using three citation databases.

Despite some reported limitations, Web of Science has been the standard source to assess the impact of individual articles, and consequently journals. By analysing the citations to articles published in the field of paediatric oncology, we demonstrate that Scopus and Google Scholar, the two new citation databases, retrieve more citations than Web of Science. The strength of Scopus lies in identifying non-English literature from Western and Eastern Europe, while Google Scholar is proficient at identifying English and non-English literature from Africa, Asia and Central and South America. These findings have implications for researchers, journals and health libraries.

Interventions other than anticoagulants and systemic antibiotics for prevention of central venous catheter-related infections in children with cancer.

BACKGROUND: Use of central venous catheters (CVC) in treatment of children with cancer is associated with infective complications. Current evidence-based guidelines to prevent catheter-related infections are mainly relevant to the adult population. They are not cancer (especially not childhood cancer) specific. Two existing Cochrane reviews have looked at prophylactic antibiotics and anticoagulants to prevent CVC-related infections. OBJECTIVES: The primary objective was to find which interventions, if any, were effective in preventing CVC-related infections in children with cancer. Further objectives were to examine the effectiveness of each intervention in the following subgroups: implanted versus external catheters, haematological versus non-haematological malignancies, and in those receiving haematopoietic stem cell transplants (HSCT) versus no HSCT. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2008, Issue 4), MEDLINE (January 1950 to January 2009), EMBASE (January 1980 to January 2009) and CINAHL(R) (January 1982 to March 2009). We also searched reference lists of relevant articles and proceedings of relevant international conferences (2004 to 2008). SELECTION CRITERIA: Randomised and quasi-randomised studies comparing any intervention (other than anticoagulants, systemic antibiotics and antibiotic lock techniques) versus no intervention, placebo or any other intervention to prevent CVC-related infections in children with cancer. DATA COLLECTION AND ANALYSIS: Two authors independently selected studies, assessed trial quality and extracted data. Where necessary, we contacted study authors for further data and clarification of methods. MAIN RESULTS: Three trials involving two different interventions were included. Two trials involving 680 children compared flushing CVC with urokinase (with or without heparin) versus heparin alone. Neither of these trials reported on the primary outcome of catheter-related blood stream infection (CRBSI). There was a non-significantly decreased rate of catheter-associated infection (CAI) (Rate Ratio 0.72, 95% confidence interval 0.12 to 4.41) in the urokinase (with or without heparin) arm compared with the heparin arm.One trial involving 113 children compared frequency of catheter dressing change every 15 days versus every 4 days. It did not report on CRBSI or CAI. There were no premature catheter removals for infection in either of the trial arms. AUTHORS' CONCLUSIONS: Three RCTs for only two types of interventions to prevent CVC-related infections in children with cancer have been identified. Flushing CVC with urokinase (with or without heparin) compared to heparin alone possibly leads to decrease in CAI rates. Changing catheter dressings every 15 days versus every 4 days does not lead to more premature catheter removals due to infection although data were insufficient to assess if catheter-related infection rates were changed.

Age-incidence patterns of primary CNS tumors in children, adolescents, and adults in England.

Around 25% of all tumors in those 0-14 years of age and 9% in those 15-24 years of age involve the CNS. They are the most common cause of cancer-related deaths in both age groups. In adults 25-84 years of age, the proportion of CNS tumors is 2%; 5-year overall survival is 10%-15%; and survivors have considerable morbidity. Comprehensive up-to-date population-based incidence data on these tumors are lacking. We present incidence rates for primary CNS tumors based on data derived from the high-quality national cancer registration system in England. A total of 54,336 CNS tumors of malignant, benign, and uncertain behavior were registered across the whole of England from 1995 through 2003. The age-standardized rates for all ages (0-84 years) was 9.21 per 100,000 person-years. This is higher than previously reported for England because it includes nonmalignant CNS tumors and hence gives a more accurate picture of burden of disease. The age-standardized rates for those 0-14 years of age, 15-24 years of age, and 25-84 years of age were 3.56, 3.26, and 14.57 per 100,000 person-years, respectively. In this article, we describe the changing patterns in the epidemiology of primary CNS tumors in these three age groups with respect to sex, tumor behavior, and histology using the current WHO classification. This information will provide a reference for future studies nationally and internationally and make comparisons relevant and meaningful.

Wilms tumour in Sudan.

BACKGROUND: Wilms tumour is one of the commonest childhood solid tumours which has an excellent outlook in the developed world with 5-year overall survival exceeding 90%. There is little information from Sudan regarding Wilms tumour. PROCEDURE: Records of patients with Wilms tumour diagnosed and treated at Institute of Nuclear Medicine, Molecular Biology and Oncology (INMO) in the University of Gezira from May 1999 to June 2007 were reviewed. RESULTS: Thirty-seven children presented at a mean age of 4.1 years (range 2 months-13 years). The male to female ratio was 0.9-1. Abdominal swelling or mass was the commonest symptom. There was 1 child with Stage I (2.7%), 7 with stage II (18.9%), 25 with Stage III (67.6%) and 4 with Stage IV (10.8%). Following diagnosis 27% of children did not receive further treatment (5.4% died prior to treatment, 5.4% were not able to finance treatment and for the rest 16.2% no cause was identified). More than half of the children did not have a nephrectomy and only 4 (11%) completed treatment. CONCLUSIONS: The poor outlook is related to several factors. Delayed presentation, poor awareness of treatment options, lack of finances, no provision of food, lodging and transport, absence of paediatric trained staff are the obstacles to better outcomes. Empowering parents with information, giving chemotherapy prior to nephrectomy, training staff and establishing links with a tertiary cancer centre in the developed world are some of the options to improve survival.

Childhood cancer in Sudan: 1999-2007.

There is paucity of information on childhood cancer from Sudan with the last studies published more than 20 years ago. This study aims to provide a current picture of childhood cancer in Sudan. Data was obtained from the hospital registry for the period May 1999 to June 2007 on all paediatric patients presenting to the Institute of Nuclear Medicine and Oncology, University of Gezira, Wad Madani, Sudan. There were 322 children with cancer during this time period with a male:female ratio of 1.6:1. Lymphomas (111, 35%), leukaemia (83, 26%) and Wilms' tumour (43, 13%) were the three most common groups of tumours. Thirty percent of all lymphomas were Burkitt's lymphoma; 3.4% of all childhood cancer cases were nasopharyngeal carcinomas.

Determinants of Treatment Abandonment in Childhood Cancer: Results from a Global Survey.

BACKGROUND: Understanding and addressing treatment abandonment (TxA) is crucial for bridging the pediatric cancer survival gap between high-income (HIC) and low-and middle-income countries (LMC). In childhood cancer, TxA is defined as failure to start or complete curative cancer therapy and known to be a complex phenomenon. With rising interest on causes and consequences of TxA in LMC, this study aimed to establish the lay-of-the-land regarding determinants of TxA globally, perform and promote comparative research, and raise awareness on this subject. METHODS: Physicians (medical oncologists, surgeons, and radiation therapists), nurses, social workers, and psychologists involved in care of children with cancer were approached through an online survey February-May 2012. Queries addressed social, economic, and treatment-related determinants of TxA. Free-text comments were collected. Descriptive and qualitative analyses were performed. Appraisal of overall frequency, burden, and predictors of TxA has been reported separately. RESULTS: 581 responses from 101 countries were obtained (contact rate = 26%, cooperation rate = 70%). Most respondents were physicians (86%), practicing pediatric hematology/oncology (86%) for >10 years (54%). Providers from LMC considered social/economic factors (families' low socioeconomic status, low education, and long travel time), as most influential in increasing risk of TxA. Treatment-related considerations such as preference for complementary and alternative medicine and concerns about treatment adverse effects and toxicity, were perceived to play an important role in both LMC and HIC. Perceived prognosis seemed to mediate the role of other determinants such as diagnosis and treatment phase on TxA risk. For example, high-risk of TxA was most frequently reported when prognosis clearly worsened (i.e. lack of response to therapy, relapse), or conversely when the patient appeared improved (i.e. induction completed, mass removed), as well as before aggressive/mutilating surgery. Provider responses allowed development of an expanded conceptual model of determinants of TxA; one which illustrates established and emerging individual, family, center, and context specific factors to be considered in order to tackle this problem. Emerging factors included vulnerability, family dynamics, perceptions, center capacity, public awareness, and governmental healthcare financing, among others. CONCLUSION: TxA is a complex and multifactorial phenomenon. With increased recognition of the role of TxA on global pediatric cancer outcomes, factors beyond social/economic status and beliefs have emerged. Our results provide insights regarding the role of established determinants of TxA in different geographical and economic contexts, allow probing of key determinants by deliberating their mechanisms, and allow building an expanded conceptual model of established and emerging determinants TxA.

Magnitude of Treatment Abandonment in Childhood Cancer.

BACKGROUND: Treatment abandonment (TxA) is recognized as a leading cause of treatment failure for children with cancer in low-and-middle-income countries (LMC). However, its global frequency and burden have remained elusive due to lack of global data. This study aimed to obtain an estimate using survey and population data. METHODS: Childhood cancer clinicians (medical oncologists, surgeons, and radiation therapists), nurses, social workers, and psychologists involved in care of children with cancer were approached through an online survey February-May 2012. Incidence and population data were obtained from public sources. Descriptive, univariable, and multivariable analyses were conducted. RESULTS: 602 responses from 101 countries were obtained from physicians (84%), practicing pediatric hematology/oncology (83%) in general or children's hospitals (79%). Results suggested, 23,854 (15%) of 155,088 children <15 years old newly diagnosed with cancer annually in the countries analyzed, abandon therapy. Importantly, 83% of new childhood cancer cases and 99% of TxA were attributable to LMC. The annual number of cases of TxA expected in LMC worldwide (26,166) was nearly equivalent to the annual number of cancer cases in children <15 years expected in HIC (26,368). Approximately two thirds of LMC had median TxA ≥ 6%, but TxA ≥ 6% was reported in high- (9%), upper-middle- (41%), lower-middle- (80%), and low-income countries (90%, p<0.001). Most LMC centers reporting TxA > 6% were outside the capital. Lower national income category, higher reliance on out-of-pocket payments, and high prevalence of economic hardship at the center were independent contextual predictors for TxA ≥ 6% (p<0.001). Global survival data available for more developed and less developed regions suggests TxA may account for at least a third of the survival gap between HIC and LMC. CONCLUSION: Results show TxA is prevalent (compromising cancer survival for 1 in 7 children globally), confirm the suspected high burden of TxA in LMC, and illustrate the negative impact of poverty on its occurrence. The present estimates may appear small compared to the global burden of child death from malnutrition and infection (measured in millions). However, absolute numbers suggest the burden of TxA in LMC is nearly equivalent to annually losing all kids diagnosed with cancer in HIC just to TxA, without even considering deaths from disease progression, relapse or toxicity-the main causes of childhood cancer mortality in HIC. Results document the importance of monitoring and addressing TxA as part of childhood cancer outcomes in at-risk settings.

The magnitude and predictors of abandonment of therapy in paediatric acute leukaemia in middle-income countries: a systematic review and meta-analysis.

BACKGROUND: Abandonment of therapy is a significant cause of paediatric cancer treatment failure in low- to middle-income countries (LMIC), but its impact has been underestimated. We performed a meta-analysis to determine the magnitude of abandonment in paediatric leukaemia in LMIC and sought to identify patient-, centre- and country-specific predictors of abandonment. PATIENTS AND METHODS: We searched seven databases to identify paediatric oncology cohorts followed up from diagnosis and treated in LMIC. All languages were included. Two reviewers independently selected articles and extracted data. Authors were contacted for additional information. Subgroup analyses were planned a priori. RESULTS: Of 22,384 publications, 318 in eight languages met criteria for full text review. 157 studies met analysis inclusion criteria. Abandonment rates (ARs), obtained for 83 of the 157 studies (52.9%), ranged from 0% to 74.5%. ARs were frequently unreported and available only directly from authors. Forty studies (10,494 children in 20 countries) were quantitatively analysed. ARs for acute lymphoblastic laeukemia in lower-middle-income countries (lower-MICs) were higher than in upper-middle-income countries (29%, 95% confidence interval (CI) 23-36% versus 2%, 95% CI 1-3%; p<0.0001) but were heterogeneous (I(2)=98%; p<0.0001). This heterogeneity was not explained by centre-specific (free versus paid treatment) or country-specific (government health expenditure, per-capital income) subgroups. CONCLUSIONS: In LMICs, ARs are highest in lower-MICs. However, their broad range suggests that low ARs are possible in resource-constrained settings. Analysis of outliers may suggest interventions for use at other centres. Methodologically appropriate reporting of ARs should be adopted. Future research should evaluate interventions targeting abandonment.