CR3 News Magazine 2023 VOL 3: MAY -- MEDICAL & LEGISLATIVE REVIEW | Page 53

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Breast cancer wouldn’t have surprised her; being among the 1 in 8 women who develop it over their lifetime isn’t statistically improbable. Neither would have colorectal cancer; knowing the risk, Mandi Pike “definitely” planned to have colonoscopies as she grew older.

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  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  in three representative U.S. hospitals found that never-smokers 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., 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 today  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 never-smokers.

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.