Different cancers predominate at different ages, and the risks and types of normal tissue damage are also associated with developmental age and the capacity for cellular repair. Humans transit through early development into a phase of homeostasis and finally senescence. When the same cancer occurs at different ages (phases of life), is it in fact 'the same'? For some cancers this is clearly not the case, while for others this may well be true. Some of the questions we address include: Why does the incidence of virtually every malignancy vary across the age range, and why do the age-specific patterns for primary malignancies differ so dramatically? Can we rationalize the differential vulnerability of developing, homeostatic, and senescing tissues to normal tissue injury? What are the similarities and differences of select malignancies (including brain, head & neck, Hodgkin lymphoma, sarcoma) according to patient age with respect to epidemiology, natural history, treatment strategies, and curability? Is the propensity to develop secondary malignancies different according to patient age at the time of treatment, and does this vary according to the primary or subsequent malignancy? Unraveling the biologic basis for cancer should clarify the impact of age on malignancy. The obverse may also be true: a greater understanding of the impact of age on malignancy may also enhance our quest to unravel its biology. At the conclusion of this activity, the learner will be able to do the following: 1. Explain the association of age with the occurrence of different cancers, and the etiologic factors (including biology and toxic exposures) responsible for the patterns of cancer genesis. 2. Describe the impact of age on the natural history and therapeutic approaches for specific cancers that occur across the age spectrum. 3. Recognize the relationship of patient age to the potential to develop late adverse treatment effects and secondary malignancies.