How do doctors discovered the link between cigarette smoke and lung cancer?

Answer 1

Researchers discovered over time that smokers had a huge increase in their deaths from lung cancer compared to non-smokers. The tar and other substances found in cigarettes were found in lungs of smokers as well. It wasn't too difficult to link it.

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From epidemiological studies. Basically, the incidence of lung cancer in a sample of smokers is compared with the incidence in a sample of a similar size of non-smokers. However, it's not that simple. There are many factors that epidemiological studies have linked with lung cancer - radon gas in the home, asbestos, family history of cancer, spread of cancer from another part of the body, eating dairy produce, drinking alcohol, traffic fumes, taking antibiotics, sawdust, having a wood burning stove and even owning a colour TV!

Epidemiology is a far from exact science. If a carpenter tragically contracted lung cancer smoked, lived in a house with high radon levels, took antibiotics, whose father or mother died of cancer and owned a colour TV, what was the cause? And then it could be down to a factor that has yet to be identified. The HPV virus, which is believed to be a major factor for Cervical cancer, is currently being investigated.