Cancer occurs in all age groups, and cancer incidence generally increases with age. There are significant differences between childhood cancers and adult cancers, with much of the difference due to the cancer cell of origin.
Childhood cancer generally originates from immature, undifferentiated cells (blastomas) or from connective tissue (sarcomas), while the majority of adult cancer usually originates from epithelial tissue (carcinomas).
In general, childhood cancer has a better prognosis than adult cancer, but there is still a large variation among cancer types. Within childhood cancer treatment, medical science has made some of its greatest recent advances, and with today's treatment methods, it is calculated that more than three out of five children with cancer are cured.
Childhood cancers consist of one third leukemia, one third in the central nervous system, and the rest in other parts of the body, all in various cancer types. The incidence of these cancer types is age-dependent; certain tumor types occur nearly exclusively in very young children. Older children and teenagers often develop cancers also occurring in adults.
Childhood cancers consist of one third leukemia, one third central nervous system tumors, and the rest various cancer types in other parts of the body. The incidence of these cancer types is age-dependent; certain tumor types occur nearly exclusively in very young children. Older children and teenagers may develop cancers that are more commonly found in adults.
There were 141 new cancer cases in children under 15 years of age in Norway in 2012. There were 78 boys and 63 girls. This constitutes less than 1% of the total number of cancer cases among the Norwegian population (1).
Incidence children, 0-14 years in the period 2008-2014 in Norway:
Among adults in Norway, the incidence of cancer has increased since the Cancer Registry of Norway began registering data in 1952, which is to a great degree due to lifestyle factors, but also because the population lives longer in general. Among children in other countries, an increased incidence of cancers has been reported (2,3). Nevertheless, an equivalent increase has not been found from 1980 to present in the Nordic countries (4).
The increased incidence in the first years of registering data is assumed to be due to more complete registration of data. Exogenous factors are of less etiological significance in pediatric cancers compared to adults since these exogenous factors often have a long latency time. Cancer caused by such factors will therefore appear after childhood.