Lung cancer rising among non-smokers -- here's why

U.S. Navy veteran John Ryan shares how he beat lung cancer, which he believes is due to an immunotherapy clinical trial he underwent at Johns Hopkins. Cigarette smoking is by far the biggest risk factor for lung cancer, data shows -- but in a surprising turn of events, the most common form of the disease is primarily found in non-smokers. Researchers at the International Agency for Research on Cancer (IARC) analyzed global trends in four main lung cancer subtypes: adenocarcinoma, squamous cell carcinoma, small-cell carcinoma and large-cell carcinoma. They found that adenocarcinoma has been the most "predominant subtype" in recent years, according to a press release summarizing the study. Younger females were found to be at a particularly high risk.