Guidelines for Complications of Cancer Treatment Vol VIII Part B

Radiation Induced Second MalignantNeoplasmIntroduction:With sustained and continuous improvements in screening,early detection, and therapy mortality from cancer hasconsistently reduced over the years resulting in improvedcancer-specific survival. In the United States, 5 year survivalfor all cancers increased from 50% to 66% in adults and from61% to 79% in children from 1975-1979 to 1996-2002 (1). Inthe latter years, the 10 year survival rates were 59% in adultsand 75% in children. Development of second malignantneoplasm (SMN) is probably one of the most sinister lateevents in long-term cancer survivors. The risk of secondmalignancies is often expressed as observed versus expectedratio (O/E ratio) calculated by dividing the observed numberof new cases by the number expected if patients in the cohortexperienced same cancer rates as the general referencepopulation. It is a measure of strength of association. Anothertool often used is excess absolute risk (EAR), defined as excesscancers per 10,000 person-years at risk (PYR) and calculatedas [(O-E)/PYR X 10,000]. It is the difference between thesubsequent cancer rate in the cohort being evaluated and the279