Usually no. There are a few very rare cancers like mesothelioma that are only caused by one thing (asbestos) or the more common squamous cell carcinoma of the cervix which is almost always caused by HPV . But usually we have no idea because cancer is an accumulation of errors. One error could be a diesel truck that spewed exhaust in your face, another error could be a cosmic ray or a random event or a chemical in the water you drank