Actually, the ACS (American Cancer Society) only attributes 31% of cancer deaths to smoking. Smoking is thought by every credible scientific source - including the National Cancer Institute - to cause 85% to 90% of lung cancers. There are many other types of cancer not associated with tobacco.
BUT - 0ne puff will not cause a respiratory tract cancer right away.
These cancers take years and many cigarettes to develop.
I'd estimate that the majority of my lung cancer patients - the hundreds that I saw over 20 years as a medical oncologist - had smoked at least 350,000 to 400,000 cigarettes by the time their cancers were diagnosed. Many had smoked over half a million cigarettes.
1 pack of cigarettes a day for 50 years is 365,000 cigarettes.
2 packs per day for 50 years is 730,000.
John Wayne was said to smoke 5 to 6 packs of cigarettes per day for decades.
He had a lung removed and survived lung cancer in 1964 after 40 years of smoking probably more than one million cigarettes. He died of another smoking related cancer (stomach cancer) 15 years later in 1979 at age 72.
Bottom line - it usually takes a great many cigarettes to cause malignancies. People often have to smoke incredible numbers of cigarettes to get into trouble. That's why I encourage my college students to stop while they are young. Their risk of lung cancer will be close to that of non-smokers once they have stopped smoking for 15 years.
MD medical oncologist with 20 years experience.
1 in 6 of my patients had lung cancers - many hundreds of people.
Almost every one had been a smoker.