The latent period before an effect on deaths was about 5 years for oesophageal, pancreatic, brain, and lung cancer, but was more delayed for stomach, colorectal,
and prostate
cancer. For
lung and oesophageal
cancer, benefit was confined to adenocarcinomas,
and the overall effect on 20-year risk of cancer death was greatest for adenocarcinomas (HR 0·66, 0·56—0·77, p<0·0001).