EXAMPLE 12 Smoking and Health

One of the earliest studies linking smoking and lung cancer was conducted by Ernst Wynder and Evarts Graham. This study compared people with and without lung cancer, looking for differences in their backgrounds or habits. The one habit that stood out was smoking. While lung cancer was rare in nonsmokers, among patients with lung cancer, cigarette use was high. The results of Wynder and Graham’s study were reported in a 1950 article in the Journal of the American Medical Association.

One potential problem with Wynder and Graham’s study was that it relied on self-reported smoking habits of people who already had lung cancer and those who did not. People who knew they had lung cancer might be more likely to overestimate how much they smoked, whereas people who did not have lung cancer might be more likely to underestimate how much they smoked.

In January 1952, E. Cuyler Hammond and Daniel Horn, scientists working for the American Cancer Society, designed a different style of study to avoid the potential problem discussed in the previous paragraph. They recruited about 188,000 men between the ages of 50 and 69. Participants completed questionnaires, which asked if they smoked cigarettes, and if so, how often and how many (along with other questions). in November 1952, Doctors Hammond and Horn collected the first follow-up set of data. These data classified participants as alive or dead (or unknown status). For those who had died, the cause of death listed on the official death certificate was recorded.

Hammond and Horn reported their preliminary findings in a 1954 article published in the Journal of the American Medical Association. They found: “The death rate from lung cancer was much higher among men with a history of regular cigarette smoking than among men who never smoked regularly.” They concluded their article stating that it was their opinion that a cause-and-effect relationship existed between regular smoking and lung cancer.