Cancers weakly related to smoking.

In 1985, review of the carcinogenic effects of tobacco led the International Agency for Research on Cancer to conclude that the smoking of cigarettes was an important cause of cancers of the lung, larynx, oro- and hypo-pharynx, oesophagus, bladder, renal pelvis, and pancreas and that the smoking of tobacco in other form was also an important cause of some of them. More evidence about common cancers has now been obtained in cohort studies and about less common cancers in case-control studies. Many are weakly related to smoking. Review now justifies the conclusion that cigarette smoking is also a cause of cancers of the stomach, renal body, liver, and nose and of myeloid leukaemia and may be a cause of cancers of the nasopharynx and lip, and that pipe smoking is a cause of cancer of the lip. Associations between cigarette smoking and cancers of the large bowel and cervix uteri may be largely, and perhaps wholly, explained by confounding.