Bladder cancer — field versus clonal origin

THE paper in this issue of the Journal by Sidransky and his colleagues on the clonal origin of multiple tumors of the bladder¹ augments our understanding of genetic changes in the bladder during early neoplasia and has implications for other common cancers. Transitional-cell cancer of the urinary bladder has an incidence rate of 15 in 100,000 and a mortality rate of 4 in 100,000; these rates increase steeply between 50 and 65 years of age and are four to five times higher in men. As with most tumors, the cause of bladder tumors is multifactorial, but exposure to chemical carcinogens.