Purpose: To evaluate the impact of cardiac disease and second malignant neoplasms on late mortality rate and to identify risk factors for late mortality among 15-year survivors of cancer diagnosed during childhood or adolescence.
Patients and methods: Gender-specific all-cause and cause-specific (cardiac disease, cancer) standardized mortality ratios were calculated. Kaplan-Meier survival estimates and Cox regression analyses were performed to determine the relationship of several demographic and treatment variables to survival.
Results: Patients who survived for 15 years after diagnosis had excess subsequent all-cause, cancer (second malignant neoplasms only), and cardiac mortality rates. No decrease in the late mortality rate by treatment era (1960 to 1970, 1971 to 1984) was identified. Risk factors for males included disease recurrence during the first 15 years after diagnosis, treatment with doxorubicin, and the diagnosis of Hodgkin's disease. Those for females included treatment with radiation therapy, treatment with an alkylating agent, and disease recurrence during the first 15 years after diagnosis. Cox regression analysis demonstrated that only an initial duration of remission of less than 15 years (P <.01) and treatment with doxorubicin (P =.08) were significantly associated with shorter survival time for males. No variable was significantly associated with shorter survival time for females in Cox regression analysis.
Conclusion: Fifteen-year survivors of childhood cancer have excess mortality. More effective treatments must be developed to reduce this excess risk. Fifteen-year relapse-free survivors did not have excess mortality. This group will require continued observation to determine whether excess mortality will become apparent as more events occur.