What Are A Smokers Chances Of Dying From Lung Cancer?

Many smokers want to know their probability of dying from lung cancer in a given time frame, however calculating precise risks can be difficult because there are a variety of factors that influence lung cancer probabilities.

The most important factors influencing lung cancer risk are age, number of years of smoking, average number of cigarettes smoked per day, number of years since smoking ceased (if the individual is a former smoker), and a history of asbestos exposure (working in a high risk occupation for at least 5 years).

Fortunately, simple calculations that provide a relatively accurate measure of lung cancer risk can be made using just age and smoking status. A study, published in the Journal of the National Cancer Institute in June 2008, used statistics from the National Center for Health to calculate the probability of an individual dying from various illnesses over the next ten years.

The table below shows the 10-year probability of dying from lung cancer for both smokers and non-smokers.

 Age  Male  Female
 Smoker  Non-smoker  Smoker  Non-smoker
 35  0.1%  -  0.1%  -
 40  0.4%  0.1%  0.4%  -
 45  0.8%  0.1%  0.7%  0.1%
 50  1.8%  0.1%  1.4%  0.1%
 55  3.4%  0.1%  2.6%  0.2%
 60  5.9%  0.2%  4.1%  0.3%
 65  8.9%  0.4%  5.5%  0.5%
 70  11.3%  0.6%  6.1%  0.7%
 75  10.9%  0.8%  5.8%  0.7%

Non-smokers in this study were defined as having smoked less than 100 cigarettes in total during their lifetime. The study aggregated data for all smokers and did not discriminate between light, moderate, and heavy smoking or when an individual had begun smoking so the probabilities above will be fairly accurate for the “average” smoker only. The average smoker smokes about 20 cigarettes a day and begins smoking between the ages of 15 and 18.

A heavy smoker who smokes 40 cigarettes per day will have lung cancer probabilities about 50% higher than the numbers listed in the table while the lung cancer risks for a light smoker who smokes 10 cigarettes per day will be about 25% lower.

The number of years a person has been smoking is a more important predictor of lung cancer risk than the number of cigarettes smoked per day so if you started smoking in mid-life rather than as a teenager, you need to adjust the probabilities listed in the table downwards. Lung cancer risk increases linearly with the square of smoking duration so doubling the duration of smoking results in about a four-fold increase in lung cancer risk. For example, a 65 year old who started smoking at the age of 15 (50 years duration) has about four times the risk of developing lung cancer than a 65 year old who started at the age of 40 (25 years duration).

For ex-smokers, the risk of lung cancer gradually reduces with time but remains slightly above the lung cancer risk of those who have never smoked. After 5 years of not smoking, a former smokers risk of lung cancer is about 33% lower than if they had continued smoking, after 10 years of not smoking, their lung cancer risk is about 50% lower than if they had continued smoking, and after 20 years, their risk is about 70% lower however they are still about twice as likely to develop lung cancer than if they had never smoked at all.