ABSTRACT
Survivors of retinoblastoma (Rb) are at high risk of dying from second malignant tumour. The occurrence of second malignant neoplasm (SMN) and related mortality in a cohort of 1111 cases from the Italian Retinoblastoma Registry was analysed, considering the possible role of both genetic and iatrogenic causes. Rb patients had a greater than 10-fold excess in overall mortality compared with the general population (standardized mortality ratio (SMR) 10.73, 95% CI 9.00-12.80). Their excess risk attributable to cancers other than Rb was 14.93 95% CI 10.38-21.49). Survivors of hereditary Rb had an SMR for all causes of 16.25 (95% CI 13.20-20.00), whereas their SMR for all cancers was 25.72 (95% CI 17.38-38.07). Survivors of unilateral sporadic Rb had an SMR of 4.12 from all cancers (95% CI 1.55-10.98) and a much higher excess for overall mortality (SMR 13.34, 95% CI 10.74-16.56). As expected, survivors of hereditary Rb had higher mortality from cancers of the bone (SMR 391.90, 95% CI 203.90-753.20) and soft tissue (SMR 453.00, 95% CI 203.50-1008.40), small intestine (SMR 1375.50, 95% CI 344.00-5499.70), nasal cavity (SMR 13.71, 95% CI 1.93-97.35) and cancers of the brain and central nervous system (SMR 41.14, 95% CI 13.2-127.55).
Subject(s)
Neoplasms, Second Primary/mortality , Retinal Neoplasms/pathology , Retinoblastoma/pathology , Cohort Studies , Functional Laterality , Germ-Line Mutation , Humans , Italy , Registries , Retinal Neoplasms/genetics , Retinoblastoma/genetics , Survival Analysis , SurvivorsABSTRACT
Two hypotheses are capable of explaining nonrandom loss of one parent's alleles at tumor suppressor loci in sporadic cases of several pediatric cancers, including retinoblastoma--namely, preferential germ-line mutation or chromosome imprinting. We have examined 74 cases of sporadic retinoblastoma for tumors in which at least two genetic events--loss of heterozygosity for chromosome 13q markers and formation of an isochromosome 6p--have occurred. Sixteen cases were found to contain both events. In 13 of 16 such tumors, the chromosomes 13q that were lost and chromosomes 6p that were duplicated are derived from the same parent. These data may be explained within the framework of the genome imprinting model but are not predicted by preferential germ-line mutation.
