The applicability of Congress' power to the agents and instruments of commerce is implied in Marshall's opinion in Gibbons v. Ogden, 628 where the waters of the State of New York in their quality as highways of interstate and foreign transportation were held to be governed by the overriding power of Congress.
Lung cancer today is primarily caused by the inhalation of smoke from cigarettes, which is also why the disease was quite rare prior to the 20th century. Lung cancer was not even recognised medically until the 18th century, and as recently as 1900 only about 140 cases were known in the published medical literature.
In a pair of good news/bad news reports, the federal government said Thursday that cigarette smoking among adult Americans continues to decline sharply but that 40 percent of all cancer diagnoses now are linked to tobacco use.