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Yes, according to a number of sources.[1][2]

[1] http://www.mayoclinic.org/healthy-lifestyle/quit-smoking/in-...

[2] http://www.cancer.org/cancer/cancercauses/tobaccocancer/smok...

Nice find.

The likely carcinogens in question: https://en.wikipedia.org/wiki/Tobacco-specific_nitrosamines

Yes.

In fact, there are also problems for smkers who cough up and then swallow phlegm - this increases risk of bladder and penile cancers.

Stomach, esophagus, and pancreas cancers are all common for people who dip. The chemical difference between smokeless tobacco and marijuana in food is probably a lot different though.