Fig. 1.

Survival curves for a subsample of cancer patients with survival data (N = 2387) divided as follows: smokers who were seen [within a year of diagnosis] more than once at the clinic and whose records indicated abstinence at atleast two follow-up points (group A); smokers who were seen [within a year of diagnosis] more than once at the clinic and whose records indicated abstinence at only one follow-up point (group B); smokers who were seen [within a year of diagnosis] more than once at the clinic and whose records indicated no abstinence at any follow-up point. Patients who did not accrue sufficient follow-up records to measure abstinence also were included in this group (group C); and smokers who were never seen at the clinic or were seen after a year from diagnosis (group D)