Understanding Statistics

The statistics on incidence and survival of childhood cancer apply to the United States. They should be viewed with the following in mind:

• Statistics describe an entire group, not any one individual’s prognosis. In other words, the outcome for an individual child cannot be forecast simply by learning the survival rate for his or her type of cancer – whether that rate is 10% or 90%. Some children survive even the most difficult cancers, and others do not survive even those with the lowest mortality rates.
• Many factors influence the prognosis of an individual child, including not only the child’s age and type of disease, but also biological and other risk factors specific to the individual child’s diagnosis.
• Survival charts are, by definition, based on outcomes for patients treated in the past. In fact, the statistics below are primarily based on the time period ending in 1995. Because research makes progress every year, today’s treatments are more advanced than those given to the children whose outcomes are shown on these charts. It will be years before enough time has passed to show survival rates from today’s treatments.

The article by Stephen Jay Gould,The Median isn't the Message is an excellant resource for demystifying childhood cancer statistics. 

Childhood cancer statistics