Strong new evidence linking smoking and bladder cancer was reported last week by a team of researchers from the National Center for Toxcological Research in Jefferson, Ark., and the University of Cincinnati. Bladder cancer strikes an estimated 47,000 Americans each year, with 10,200 of them dying. Researchers have previously estimated that 40% to 85% of bladder tumors are caused by smoking.
The researchers studied bladder biopsies from 13 smokers, nine nonsmokers and 20 ex-smokers. They reported in the Proceedings of the National Academy of Sciences that DNA--deoxyribonucleic acid, the genetic blueprint of life--from the bladder cells of smokers was chemically linked to carcinogens normally found in tobacco smoke. Such linking is thought to be the first step in chemical carcinogenesis, the process by which chemicals causes cancer.
The so-called DNA-carcinogen adducts were present in sharply lower concentrations in both nonsmokers and ex-smokers who had not smoked for at least five years. The latter finding suggests that genetic damage caused by smoking can be reversed over time.