If you tell a colleague that a relative was recently diagnosed with lung cancer, their first question will most likely be "Were they a smoker?" or something along those lines. If you were to tell that same colleague that your relative was diagnosed with stomach, brain, pancreatic or another type of cancer, their first reaction would be pure sympathy.
The common sigma that is associated with lung cancer is that the person with the cancer is at fault. As children (and even adults), we are shown photographs of the "non-smoker" versus "smoker" lungs (shown above). The pictures make it out to be that smokers are destroying their own bodies and that lung cancer and living on an oxygen tank is simply inevitable. But the stigma with stomach or brain cancer is that it's fairly random. Smoking does contribute to lung cancer, but it doesn't necessarily cause lung cancer. Over 60% of lung cancer diagnoses are for people who have never smoked before.
With that being said, however, smoking is the number one contributor to lung cancer - right behind pollution (people who live in cities are more susceptible to this). And not only that, but lung cancer is the deadliest cancer. It is responsible for over 25% of all cancer-related deaths.
It's interesting that there is such a stereotype for lung cancer being a "for smokers only" type of diagnosis. There are many Americans living in New York City that are exposed to just as many carcinogens as smokers that are just as likely to contract lung cancer in their lifetime.