Well, if you want to go down the rabbit hole of causation, there is very little you can say definitely, as proving causation is practically impossible. So you can never say what caused any disease. Having said that, most diseases are multifactorial in origin, with cells mostly having multiple insults to lead to cancer- both on an individual cell and cell population basis. For types of cancer associated with smoking (like non adenocarcinomas of the lung), its likely that smoking contributed to at least one of the insults causing a cell to undergo metaplasia/dysplasia or become cancerous, or statistically would be likely to lead to that cancer on a cell population basis.