Guidelines for Complications of Cancer Treatment Vol VIII Part B

ate expected in the standard population which is used tomeasure the overall burden due to subsequent cancers.Burden:The Surveillance, Epidemiology & End Results (SEER) dataon SMN based on nine cancer registries involving over 2million cancer patients reported an overall 14% higher risk ofnew malignancies (O/E=1.14; 95%CI=1.14-1.15) in cancersurvivors than would be expected in general population[Table I].In the SEER database (2), nearly 14% of all patients developeda second cancer by 25 years of follow-up (cumulative incidenceof 5.0%, 8.4%, 10.8%, and 13.7% at 5, 10, 15, and 25 years,respectively). The aetiology of SMN can reflect the latesequelae of treatment; the influence of lifestyle factors,environmental exposures, and host factors; and combinationsof influences, including gene-environment and gene-geneinteractions. Travis and colleagues (3) categorized SMN intothree major groups according to dominant etiologic factors(ie. treatment-related, syndromic, and those attributable toshared etiologic influences) underscoring the non-exclusivityof these delineations. The incidence of second primary cancerhowever varied according to age group (1). In childhoodcancers, the all-cause mortality and overall risk of subsequentcancer was very high (O/E=6.13), as compared to the elderlypopulation where the risk of a SMN was much less (O/E=0.93).In a subgroup analysis (2), the incidence of subsequent primarycancers was evaluated in a cohort of 23,819 2-month survivorsof childhood cancer diagnosed at ages less than 18 years during1973-2000 and followed for an average of 8.3 years. Childhoodcancer survivors were at more than 6-fold increase in risk ofdeveloping a new cancer relative to the general population(O/E=6.07, O=352, EAR=15 per 10,000 person-years). Thecumulative incidence of second cancers at 25 years after280