The CCSS has the ability to continue investigating this aging population and to understand the factors that increase their risk of subsequent neoplasms (SNs).Here we summarize the knowledge gained about the incidence and characteristics of second cancers in individuals who were diagnosed with childhood cancer between 1970 and 1986 and report the most prevalent SNs that occur in this cohort before they reach 21 years of age and have survived their primary disease for at least 5 years.