By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) - It is a classic study performed in Oslo and it holds up as a landmark report.

The end result of the study is smokers who believe a few cigarettes a day don’t do any harm will need to think again.

Scientists who studied the health records of 43,000 men and women have shown that smoking fewer than five cigarettes a day, commonly known as light smoking, triples the risk of dying of heart disease or lung cancer in men. In women the increased risk of lung cancer was five times greater.

The researchers looked at a 32-year period, starting in 1970. Now, we already know that smokers die on average ten years earlier than non-smokers. But many have believed just a few cigarettes are harmless, and clearly we need to learn from that message that smoking is bad no matter what you do, and the quicker you cut it, the better.