The study concluded that long-term tobacco usage contributes to the onset of lung cancer, as an overwhelming majority (96.5%) of the men with the disease were classified as moderate to heavy smokers for an extended period of time, compared to a lower percentage of the general hospital population control group.
[2] In 1775, Percivall Pott’s discovery of the high incidence of scrotal cancer in chimney sweeps demonstrated that charred organic substances were carcinogenic.
[3] In 1912, Isaac Adler connected the rise in primary lung cancer to consumption of cigarettes because of the different smoking habits of men and women.
[5] Richard Doll, a prominent scientist who conducted the British Doctors Study with Austin Bradford Hill in 1951, theorized that smoking was not considered an obvious factor because everyone participated in it, yet not everyone developed lung cancer.
Scientists believed many other factors were responsible for the development of lung cancer, such as automobile exhaust, coal fumes, infectious diseases, race, and better diagnostic technologies.
[8] This follows the upward trend of smoking that peaked 20 years prior due to its social pervasiveness, global association with glamour and camaraderie, and the heavy influence of the tobacco industry.
[11] The objective of this research was to design a clinical study to assess multiple external factors in the onset of bronchogenic carcinoma, and which activities or predisposed determinants increase risk for lung cancer.
[12] The survey included questions about smoking: starting age, 20 year tobacco consumption, brands used; as well as inquires about exposure to hazardous agents in the workplace, alcohol use, and causes of death for family members.
Since hospital records provided insufficient information for the scope of this study, trained staff interviewed 634 patients, and the remaining subjects were either mailed the survey or had a close contact answer on their behalf.
Furthermore, control studies were added to minimize bias from interviewers, and the compare the incidence of lung cancer with exposure to other factors among the different groups.
Individuals in the study were evaluated based on average daily consumption of cigarettes, age, history of disease, and occupation - the latter two to avoid confounding variables.
Researchers wondered if there was a connection between an increased consumption of cigarettes for a longer period of time and a higher prevalence of lung cancer in these individuals, excluding adenocarcinoma.
There was also an evident dose-response relationship: as average daily cigarette consumption increased, so did the number of people with lung cancer as opposed to ones without the disease.
Additionally, cigarette usage was shown to contribute to the development of other forms of cancer and heart disease[12] Also, the control studies conducted by "third party" physicians exhibit corresponding results to the data gathered by researchers.
[10] Additionally, the tobacco industry obscured and distorted these scientific conclusions to dissuade public recognition of the harmful results of smoking, and denied causal link between cigarettes and lung cancer.