Cancer in adolescents and young adults (AYA) represents a higher fraction of all cancer in countries that are still undergoing a demographic transition. Such countries tend to have much younger populations, and therefore unless they have a particularly low incidence of cancer in this age group, will have a higher burden of cancer (absolute number of cases with cancer) in AYA. Cancers in AYA are comprised of the tail end of the incidence curve of cancers that have their peak incidence, or occur almost exclusively in childhood, the beginning of the incidence curve of cancers that primarily affect the elderly, and a third set of cancers that have their peak incidence (or are at least common) in the AYA age group (e.g., testicular cancer, sarcomas, melanoma, thyroid cancer). Many, but not all, of these cancers require radiation or cancer surgery, but the poorest countries do not have a sufficient number of radiation therapy units and surgical oncologists, or indeed medical and pediatric oncologists, to deal with the burden of cancer they face. The AYA age group is particularly important, both with regard to their contribution to the economy now and in the future (the majority are in the "working" age-group defined as 15-64 years), as well as their important role in caring for their families. Moreover, some of these cancers are eminently curable with chemotherapy alone, and more could be cured by simply improving the efficiency of existing health services and providing education and training to both the public as well as oncologists and other specialists required for the care of AYA (although such individuals will not necessarily be exclusively concerned with this age group). Of particular importance is the detection and diagnosis of cancer patients at the earliest possible time in the course of their disease. Avoiding delays in initiating therapy, which are partly due to the poverty and lack of education of the public as well as to a failure on the part of primary health care providers to recognize the possibility of cancer, would lead not only to improved survival and less toxicity, but is likely to reduce the need for radiation as well as the cost of treatment. There are few good quality clinical trials that take place in the LMIC (in relationship to the extent of the existing cancer burden), and research training should be an integral component of capacity building. Research on the efficacy and toxicity of standardized treatment approaches that are either based on principles established in the HIC, or adapted from treatment protocols used in the HIC, would be a good place to begin, but health policy and multisectoral collaboration are essential if improved survival rates are to be achieved. Decisions will also need to be made regarding the treatment of diseases in which radiation or cancer surgery are important elements, when one or both of the latter are unavailable. Late effects are important in this young population in HIC, and protocol adaptations or design in LMIC should take into consideration the significant fraction of cured patients with late effects who were treated in HIC in an era where improving response and survival rates was the paramount consideration-the situation that applies today in less developed countries. Special adolescent units which better deal with psychological issues of young cancer patients are rare in LMIC and the psychosocial issues faced by adolescents are much less studied. Although survival is the first consideration, attention to psychosocial and financial issues may reduce existing delays in initiating therapy and also the fraction of patients that abandon therapy.