Facts and Figures

• More than 7,300 non-smokers in the United States die of lung cancer each year caused by secondhand smoke.
• Measurements of cotinine show that exposure to secondhand smoke among children who live in homes without any indoor smokers is 45% higher in children living in multi-unit housing, such as apartments and condos, than those living in single-family homes, despite neither of the homes having indoor smokers.
• There are more former smokers diagnosed with smoking-related lung cancer than current smokers each year, with the risk of contracting the disease remaining high, up to 25 years after quitting.
• About 40% of diagnosed lung cancer cases involve people who had quit smoking more than 15 years before the diagnosis, while 20% of women who develop lung cancer have never been smokers.
• The risk of developing lung cancer for former smokers decreases with the number of years compared to non-smokers as follows:
• 5 years after quitting: 12.12 times higher than that of a never-smoker
• 5–10 years after quitting: 11.77 times
• 10–15 years after quitting: 7.81 times
• 15–25 years after quitting: 5.88 times
• Over 25 years since quitting: 3.85 times
• It is of interest that even after 25 years of quitting, former smokers are almost four times (3.85) more likely to develop lung cancer compared to never-smokers.
• However, current smokers who quit after their lung cancer diagnosis can heal and respond to treatment, reducing their mortality from some cancers by up to 40%. 
• Smoking can cause cancer almost anywhere in the body, not just the lungs, including the blood (acute myeloid leukemia), bladder, cervix, colon and rectum, esophagus, kidney and renal pelvis, larynx, liver, lungs, trachea, and bronchus, mouth and throat, pancreas, and stomach.

Summary

• In our preliminary research, we have provided some facts and figures related to how being a former smoker correlates to lung cancer, including secondhand smokers.
• We can continue the research to provide insights covering both lung cancer and other lung health issues. Below is our recommended research path.