Postdiagnosis Smoking Cessation Tied to Improved Lung Cancer Outcomes

Lisa Rapaport

August 02, 2021

(Reuters Health) — Current smokers who quit after they're diagnosed with early-stage lung cancer have better overall and progression-free survival than counterparts who continue smoking, a small study suggests.

Researchers examined data on 517 current smokers who were diagnosed with early-stage (IA-IIIA) non-small cell lung cancer and prospectively followed for an average of 7 years. Median overall survival was 5.2 years, but median overall survival was 21.6 months longer among patients who quit smoking than those won continuously smoked.

"There are many carcinogens in tobacco smoke including polycyclic aromatic hydrocarbons and nitrosamines, that can cause further damage to the cells and to the DNA of the normal and tumor cells," said lead study author Dr. Mahdi Sheikh of the Genomic Epidemiology Branch at the International Agency for Research on Cancer at the World Health Organization in Lyon, France.

"This can facilitate the development of existing and new cancers and might accelerate tumor growth and progression," Dr. Sheikh said by email.

During the study period, a total of 325 patients died, including 271 cancer-specific fatalities. In addition, local recurrence or metastasis occurred in 172 patients.

A total of 220 patients quit smoking, including 157 (71.3%) who did so shortly after diagnosis and prior to starting treatment.

Five-year overall survival was higher for patients who quit (60.6%) than for patients who continued smoking (48.6%). Progression-free survival was also higher among patients who quit smoking (54.4%) than among those who didn't (43.8%).

Smoking cessation was associated with significantly lower all-cause mortality (hazard ratio, 0.67), cancer-specific mortality (HR, 0.75), and tumor progression (HR, 0.72) in adjusted analysis that accounted for factors including diagnosis year, age, sex, education, BMI, chronic disease history, cumulative cigarettes smoked, alcohol use, tumor characteristics, and treatment regimen.

One limitation of the study is that some outcomes, including tumor progression information and ultimate cause of death, might be subject to variation in the accuracy of medical records and death certificates, the study team notes in the Annals of Internal Medicine.

Other limitations include the potential for inaccuracies in self-reported smoking data as well as the potential for smoking cessation to be associated with unmeasured confounders that influenced lung cancer outcomes.

However, there are several possible reasons that smoking cessation after a lung cancer diagnosis might lead to better survival outcomes, said Dr. Nancy Rigotti, director of the Tobacco Research and Treatment Center at Massachusetts General Hospital in Boston and author of an editorial accompanying the study.

Chemicals in cigarette smoke may promote the growth of tumors, and smokers also have a poorer response to cancer treatments, in part because they suffer more toxicity to cancer treatments, Dr. Rigotti said by email. Smokers who quit may also reduce their risk of dying of other smoking-related diseases like heart attacks, strokes, and chronic lung disease, contributing to improvements in overall survival.

"I suspect that the finding may surprise smokers and even some of their doctors, who may have assumed that it is too late to benefit from quitting smoking after being diagnosed with lung cancer," Dr. Rigotti said. "This study clearly shows that it's not."

SOURCE: and Annals of Internal Medicine, online July 27, 2021.