Figure 4 – Odds ratio^a,b of oral and pharyngeal cancer and laryngeal cancer in former smokers who quit ≥10 years ago, for the joint effect of intensity (cigarettes/day) and duration (years) of cigarette smoking estimated through bivariate spline models. INHANCE consortium.

^a Fitted models included adjustment for age, sex, race, study, education, drinking status, drinking intensity, and drinking duration. The reference category was defined as “Never smokers”. ^b On the grid, the black thicker line represents the knot location: 27 cigarettes/day for laryngeal cancer. Dark grey lines in contour plots indicate iso-risk curves at defined levels of risk.