Time Since Stopping Smoking and the Risk of Oral and Pharyngeal Cancers

Extract

In the largest study to date of oral and pharyngeal cancers that contained 1114 case subjects and 1268 control subjects from four areas of the United States, cessation of smoking was associated with a sharply and markedly reduced risk (1). The odds ratio (OR) for all current smokers combined was 3.4 for males and 4.7 for females. For ex-smokers (i.e., subjects who had not smoked for at least 1 year), the OR was 1.1 for males and 1.8 for females 1-9 years after smoking cessation, 1.1 for males and 0.8 for females 10-19 years after cessation, and 0.7 for males and 0.4 for females 20 years or longer after cessation.

Such a drop in risk in a relatively short time suggested that smoking mainly affects the later stages of oral and pharyngeal carcinogenesis (1) and, if confirmed, would have relevant public health implications. However, the U.S. veterans cohort study (2) showed elevated risks of oral (relative risk = 1.5) and pharyngeal (relative risk = 2.6) cancers in all former smokers combined.