The associations between the original and second cancer diagnoses are shown in Table 2. SMNs of the breast and gastrointestinal tract most commonly followed a primary diagnosis of HL. Second thyroid cancers were most common in leukemia and HL survivors, as were skin cancers (melanoma and NMSC). Second sarcomas predominantly occurred among survivors of primary soft tissue sarcoma or HL. Second hematopoietic cancers most commonly followed a primary diagnosis of HL or leukemia. Second malignancies of the CNS most commonly occurred after original diagnoses of a CNS tumor or leukemia. This represents a 2.3-fold increase over the 314 SMNs that occurred in 298 survivors as of January 1, 2000, as identified during the first comprehensive analysis of these events in the CCSS cohor