C urrent cancer screening guidelines 10 recommend a CT scan for anyone 50 to 80 years old who has smoked at least 20 pack years ( the equivalent of one pack a day for 20 years , or two packs
a day for 10 years , and so on ) and who is still smoking or quit less than 15 years ago . Screening is not recommended for never-smokers because the costs of doing so are deemed greater than the benefits , Jemal said ; thousands of never-smokers would have to be screened in any given year to find one lung cancer .
Still , low-dose CT can catch lung cancer in a significant number of never-smokers . A 2019 study in
South Korea 11 diagnosed lung cancer in 0.45 % of never-smokers , compared to 0.86 % of smokers . The researchers urged policymakers to “ consider the value of using low-dose CT screening in the
never-smoker population .”
“ It used to be that the high-risk group ” for whom CT screening is recommended “ was the vast majority of lung cancer patients ,” Heymach said . “ But now that so many lung cancer cases are in nonsmokers , there is absolutely a need to reevaluate the screening criteria .”
Researchers are trying to improve screening by reducing the incidence of false positives — when CT finds lung nodules “ or an old scar that you got 20 years ago ,” he said . Those don ’ t pose a threat but have to be biopsied to ascertain that . Screening never-smokers would also be more efficient than it is today “ if we could identify who , among nonsmokers , are at higher risk ,” he said .
Cancer doctors already know part of the answer : women . Worldwide , 15 % of male lung cancer patients are never-smokers . But fully half of female lung cancer patients never smoked . And women never-smokers are twice as likely to develop lung cancer as men who never put a cigarette to their lips .
Beyond sex , “ nothing stands out as a single large risk factor that , if we only got rid of it , we would solve the problem ” of lung cancer in never-smokers , said Josephine Feliciano , an oncologist at Johns Hopkins University School of Medicine . “ But air pollution , radon , family history of lung cancer , [ and ] genetic predispositions ” all play a role . Chronic lung infections and lung diseases such as chronic obstructive pulmonary disorder ( COPD ) also seem to increase risk .
None of those , with the possible exception of genetics and indoor pollution ( cooking fires in some low-income countries ), affect women more than men . So what ’ s going on ?
At least one biotech believes that biological differences between lung cancer in never-smokers and smokers merits a new drug , and one that might be especially effective in women . “ A different disease needs a different drug ,” said co-founder and CEO Panna Sharma of Lantern Pharma . In fact Lantern , which is developing a drug for lung cancer in female never-smokers , believes that disease is so different it recently tried to convince the U . S . Food and Drug Administration to designate it an orphan disease , said Sharma .