The majority of less developed countries do not have cancer registries and out of the existing registries very few are population-based. In the absence of population-based registries, it is impossible to evaluate not only the incidence of childhood cancer but also the proportion of children who do not access care. Their numbers should be substantial, even in high-medium income countries (i.e. those with GNI’s between USD 4,036 and 12,475). South Africa offers an example: according to the GLOBOCAN estimations of an incidence of 85 childhood cancers per million, around 1,300 new cases should appear every year. However, the South African Children’s Cancer Registry, which is hospital-based and covers the whole country, only counted between 546 and 723 cases yearly between 1997 and 2007 [11].

Another example originates in Brazil, where in 2009 a number of 234 High Complexity Cancer Care Centers existed, which were equipped and staffed to treat cancer in children and adolescents. In these centres, the mortality from cancer in children, as well as the number of therapeutic procedures, was seen to be much smaller in the northern regions than in the southern ones. At the same time, the proportion of childhood deaths from ill-defined causes, which can be a proxy for the number of children not reaching the health care system, was higher in the north. As the units were planned to cover a roughly similar number of children in the territory, and the incidence of childhood cancer was considered to be generally uniform, the authors concluded that a larger number of children with cancer in the North were never seen at a Cancer Centre before their death [12].

Large time gaps from the clinical onset of the disease to instituting the therapy would allow time for progression of the malignancy towards more advanced and difficult to treat stages. Most of the studies addressing the delay from first symptoms to diagnosis and treatment were done on high-income countries [13, 14]. They present evidence for significant progression of the disease during the time elapsed before the child entered the health care system. Research done in Mexico on the risk factors for delay found that Hodgkin disease, the lower standard of education of the mother, the absence of coverage of the patient by health insurance and the longer distance between home and hospital were correlated with longer delays to the beginning of treatment [15]. Data published from South Africa indicated that in 58 % of cases the initial diagnosis was wrong and the persistence of symptoms in spite of various initial treatments was the most frequent reason to think of malignant disease. In that study, the most important contributor to delay was the physician [16].

A recent systematic review and meta-analysis of the literature describing the magnitude of treatment abandonment and its associated factors, in cases of acute leukaemia in children, found that it was vastly different in various studies, from 0 to 74.5 %. The rates were significantly higher in lower-middle income countries (please see definition above), at 29 %, while in higher-middle income countries the figures found were around 2 % (p < 0.0001). However, the heterogeneity of the higher rates was interpreted by the authors as an indicator that the abandonment could be reduced, even in restricted resource settings. The analysis could not find clear explanations for the heterogeneity [17].

Another recent, retrospective study, addressing the causes of abandonment of treatment for retinoblastoma in Uttar Pradesh, India, contributes more details to the understanding of the matter: out of 101 children, 50 (49.5 %) defaulted. Around one-third of those families could be traced; the lack of finances and the rejection of enucleation as a means of treatment were the major reasons given for abandonment [18]. A few children returned to complete their treatment, with more advanced disease, which reduced their survival to 50 %, while 75 % of those who never returned died during the monitoring period. Additional statistic data from Delhi, India, this time on a variety of cancers, indicated that the cost of treatment, the great distance to the hospital (over 100 km), the belief that cancer was incurable and the female sex of the child were the reasons given by the parents for discontinuing the therapy [19].