We are sorry to hear that your father died young. Our motivation for the work we do is to try to keep nicotine users from needlessly dying young
However, there is very, very little chance that his cancer was actually caused by smokeless tobacco. It is a natural human tendency to assign a specific cause to events, especially major bad events. But the nature of some diseases, like most cancers and heart disease, is that there is very seldom one clear cause.
When someone tries to find a cause anyway, it is easy to assign the blame to an exposure that is popularly vilified, like smokeless tobacco. Indeed, those who want to vilify the exposure may cynically take advantage of the disease case to try to bolster their case. But neither they nor anyone else can claim to see causation in a particular case. Scientific methods are designed to deal with this challenge, by seeing if there is an overall elevated rate of disease among people who are exposed. In this case, that scientific evidence does not support the conclusion that smokeless tobacco causes stomach cancer. The evidence indicates such a low risk that even a smokeless tobacco user who got stomach cancer would almost certainly have been predisposed to get it anyway.
The exposure most identified with stomach cancer is not eating enough fruits and vegetables, and most experts also cite smoking and infection with the bacteria Helicobacter pylori (usually a life-long infection acquired in childhood). For some people, preserved meat and lack of refrigeration for food or occupational exposures are identified as causes. Unlike a smoker who gets lung or oral cancer (where we can conclude that it was almost certainly caused by smoking) assigning a specific cause to stomach cancer is difficult. Whoever told you that this cancer was caused by smokeless tobacco had no scientific basis for doing so, and was probably a victim of the misleading anti-smokeless-tobacco propaganda.
We appreciate the reminder about the tendency of anti-harm-reduction advocates to assign blame for some cancers to smokeless tobacco, even though such claims do not have scientific support. We have added an FAQ entry about this point: http://tobaccoharmreduction.org/faq/healtheffectsofst.htm#38 . We realize that learning that smokeless tobacco was very unlikely to have caused this cancer does not make you any better off, but we hope it might help others who will not be scared away from switching from smoking to smokeless tobacco due to misunderstandings about the comparative cancer risks.
Carl V Phillips