Do Reductions in the Tar and Nicotine Yields of Cigarettes Help to Explain Recent Reductions in Lung Cancer Rates in Young Men and Women in the United States?

Abstract

Between 1985 and 2000, lung cancer rates in U.S. men and women aged 35-54 yr have declined. To investigate whether these declines can adequately be explained by changes in smoking prevalence, consumption, and duration, or if changes in tar and nicotine yields also contributed, two model-fitting approaches were used. Both approaches used individual person National Health Interview Survey data on smoking prevalence, age of starting and time of quitting, and national estimates of consumption per smoker and yields. Both approaches compared observed rates (by sex and age) relative to 1985, with those predicted after successively including various smoking variables into the model, making varying allowance for compensation for reduced yield. Approach A was simpler, based on mean smoking statistics estimated separately for current and former smokers. Approach B used the multistage model and individual smoking histories to estimate risk. Both approaches showed observed declines in risk were (except for men aged 35-39 yr) clearly greater than predicted based only on prevalence, consumption, and duration. Including yield generally improved the fit. At younger ages, models assuming substantial compensation (consistent with evidence from studies relating nicotine yield and intake) fitted well, but at age 50-54 yr in both sexes and age 45-49 yr in women, the decline was better fitted by models assuming little compensation. The conclusions were not sensitive to the precise parameter values assumed in the modeling. Interpretation is not straightforward, but the findings suggest declines in yields have contributed to the recent declines in rates in young U.S. men and women.