From what I have read the risk of cancer from snus is essentially zero, and that comes from a number of sources. The risk from dip is so low at this point it is hard to find in studies. At worst it has a 10% to 20% increase risk for oral cancer compared to a non-tobacco user. The risk from smoking is somewhere around 800% to 1000% increased risk for oral cancer, not to mention all the other types of cancer, COPD, and a long list of other risk from smoking.
Smoking is perhaps 100 times more risky then smokeless. If there is an increased risk in dip compared to snus it is very slight.
As a point of interest moist snuff was invented in Sweden with what we now call snus. The Swedes who immigrated to the US missed their beloved snus and started making their own version which we now call dip. It's all related.