Some smokers get lung cancer and others do not. The reason for this may involve bacterial infection, according to a review by Dr. Seyed Javad Moghaddam of the University of Texas MD Anderson Cancer Center, Houston, Texas, and colleagues at three other research institutions. Nontypeable Haemophilus influenzae (NTHi) is the main culprit, they reported. This pathogen is similar to Haemophilus influenzae type b (Hib), which is a common cause of meningitis, pneumonia, and ear infections in children who have not been vaccinated against it. The nontypeable variety is missing the polysaccharide capsule present in Hib and other, less common varieties.
The NTHi bacteria colonize the upper respiratory tract of 75 percent of healthy individuals, and generally cause no problems. Lower respiratory tract infections, however, are common in adults with chronic obstructive pulmonary disease (COPD), and contribute to airway inflammation. COPD is strongly associated with smoking and lung cancer: five out of ...
https://www.empowher.com/cancer/content/bacterial-link-lung-cancer