Outcome of lesions that were normal, hyperplasia, metaplasia, mild dysplasia, moderate dysplasia, or severe dysplasia at baseline. Subjects free of lung cancer on follow-up for each histology grade are shown in a, c, e, g, i, and k, and those who developed CIS or invasive cancer in the same site or a distant site are shown in b, d, f, h, j, and l. The progression rates are higher in the cancer group and reach statistical significance for lesions that were normal or moderate dysplasia at baseline (P=0.04 and 0.045, respectively; 2 by 2 comparison, one-tailed Fisher exact test)