Former smokers of both sexes in the CPS II and contemporary cohorts had lower age-standardized rates of death and relative risks of death than did current smokers, for all the end points studied (Tables 2 and 3). The rates of death from cardiovascular conditions among men and women who were former smokers decreased significantly from the 1960s to the contemporary period, but the rates of death from lung cancer and COPD increased among women. Former smokers who had stopped smoking at earlier ages had progressively lower relative risks of death from lung cancer and COPD, as compared with current smokers in the contemporary cohorts (Fig. 2, and Table S6 in the Supplementary Appendix). Those who quit smoking by 40 years of age avoided nearly all the excess smoking-related deaths from these conditions; even those who quit smoking before 60 years of age had a lower relative risk than those who did not quit but smoked fewer than 10 cigarettes per day. Strong inverse relationships were also observed between years since quitting and deaths from these end points (Tables S6 through S13 in the Supplementary Appendix).
