Retinoblastoma (cancer of eye retina), neuroblastoma (cancer of the peripheral nerve tissue), and Wilm's tumor (kidney cancer) usually are found only in very young children.
Retinoblastma, usually present within the first year of life with the average age at diagnosis being 9 months.
Half of the cases of neuroblastoma occur in children younger than two years old, and Wilm's tumor is diagnosed at a mean age of 3.5 years.
Generally, rates of cancer incidence are highest among infants, decline until age 9, and then rise again with increasing age.
In other words, children under 5 and those aged 15-19 experienced the highest incidence rates of cancer.

Thanks for the reply, but I guess I did not pose my question correctly. I am attempting to determine when in the history or humans, children started getting cancer. Like 1990, 1970, 1950, or even before that? I am unable to find any information on this anywhere and would appreciate any opinions...