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.
Health risks are similar to cigarette smoking in nicotine addiction, periodontal health, tooth loss, and many types of cancer, including cancers of the mouth, throat, and esophagus. Cigar smoking also can cause cancers of the lung and larynx, where the increased risk is less than that of cigarettes.