But when a PET scan in November 2019 revealed that Pike , a 33-year-old oil trader , wife , and mother of two in Edmond , Okla ., had lung cancer — she had been coughing and was initially misdiagnosed with pneumonia — her first reaction was , “ but I never smoked ,” she said . “ It all seemed so surreal .”
Join the club . Cigarette smoking is still the single greatest cause of lung cancer , which is why screening recommendations apply only to current and former smokers and why 84 % of U . S . women and 90 % of U . S . men with a new diagnosis of lung cancer have ever smoked , according to a study published in
December 4 in JAMA Oncology . Still , 12 % of U . S . lung cancer patients are never-smokers .
Scientists disagree on whether the absolute number of such patients is increasing , but the proportion who are never-smokers clearly is . Doctors and public health experts have been slow to recognize this trend , however , and now there is growing pressure to understand how never-smokers ’ disease differs from that of smokers , and to review whether screening guidelines need revision .
“ Since the early 2000s , we have seen what I think is truly an epidemiological shift in lung cancer ,” said surgeon Andrew Kaufman of Mount Sinai Hospital in New York , whose program for never-smokers has treated some 3,800 patients in 10 years . “ If lung cancer in never-smokers were a separate entity , it would be in the top 10 cancers in the U . S .” for both incidence and mortality .
A 2017 study of 12,103 lung cancer patients 7 in three representative U . S . hospitals found that neversmokers were 8 % of the total from 1990 to 1995 but 14.9 % from 2011 to 2013 . The authors ruled out statistical anomalies and concluded that “ the actual incidence of lung cancer in never smokers is
increasing .” Another study that same year , of 2,170 patients in the U . K 8 ., found an even larger increase : The proportion of lung cancer patients who were never-smokers rose from 13 % in 2008 to 28 % in 2014 .
“ It is well-documented that approximately 20 % of lung cancer cases that occur in women in the U . S . and 9 % of cases in men , are diagnosed in never-smokers ,” Kaufman said .
To a great extent , this is a function of straightforward math , said epidemiologist Ahmedin Jemal of the American Cancer Society . Fewer people smoke today9 than in previous decades — 15 % in 2015 , 25 % in 1995 , 30 % in 1985 , 42 % in 1965 . Simply because there are fewer smokers in the population , out of every 100 lung cancer patients , fewer will therefore be smokers . And that means more of them will be neversmokers .
There are also hints that the absolute incidence of lung cancer in never-smokers has been rising , said oncologist John Heymach of MD Anderson Cancer Center . Some data say it has , but other data say no . The stumbling block is that old datasets often don ’ t indicate a lung cancer patient ’ s smoking status , Heymach said , making it impossible to calculate what percent of never-smokers in past decades developed lung cancer .
Jemal , however , cautions that it is not the case that a never-smoker has a greater chance of developing lung cancer today than never-smokers did in the past .