Analysis of the markedly increased incidence of cancer in individuals with Blooms Syndrome. W. Shi¹, A. Zauber¹, M. Sanz^2,3, J. German³. 1) Dept. Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY; 2) Dept. Biology, Molloy College, Rockville Centre, NY; 3) Dept. Pediatrics, Weill Medical College of Cornell University, New York, NY.
   Blooms syndrome (BS) is a rare recessively transmitted form of proportional dwarfism. A single locus is mutatedBLM that encodes the nuclear protein BLM that when absent or non-functional also results in a mutator phenotypethe clinical consequence is cancer of a wide variety of cellular types and anatomical sites. We determined the standardized incidence ratio (SIR) of specific types of cancers diagnosed in 237 individuals with BS (BSI) ascertained since 1954 by the Blooms Syndrome Registry. The number of cancers expected to arise was calculated based on age, sex, and calendar interval-specific rates published by the Surveillance, Epidemiology, and End Results (SEER) program, NIH. 138 primary invasive cancers were diagnosed in 108 BSI during 4952 person years of follow-up. The mean age of diagnosis of the first primary cancer was 23 years (SD=12). The SIR (95% CI) by sex (M=128, F=109) is given below. An almost 100 fold increased risk of cancer existed for BSI as compared to the general population. A markedly increased risk of developing cancer exists for both males and females with BS. Early and continued surveillance for cancer is critical for affected individuals.