Smoking Cessation Improves Survival Up to Two Years Before a Lung Cancer Diagnosis

People who quit smoking at any time, even up to two years before a lung cancer diagnosis, will improve their chances of survival after being diagnosed, according to results of a study presented at the virtual scientific program of the 2020 American Society of Clinical Oncology (ASCO) Annual Meeting.  

The researchers found that those who quit smoking more than five years before their lung cancer diagnosis had a 20% reduced risk of death from all causes, smokers who quit 2-5 years prior to their diagnosis had a 16% reduced risk of death and smokers who quit less than 2 years before their diagnosis had a 12% reduced risk of death compared to current smokers.  

 

“This research shows that if you’re a smoker and you quit, no matter when you quit, you will be more likely to survive after being diagnosed with lung cancer, compared to someone who continues smoking,” said Dr. Aline Fusco Fares, lead author of the study and is a clinical research fellow at the Princess Margaret Cancer Centre in Toronto, in a press release. “The study’s message is simple: quit smoking now.”   

 

In the study, researchers confirmed that there is a better overall survival for patients with lung cancer who never smoked compared to those who did. They looked at data that included the time on smoking cessation from 17 International Lung Cancer Consortium (ILCCO) studies that made up a population of 35,428 patients with lung cancer, 47.5% of which were current smokers, 22.5% never smoked and 30% were former smokers at the time of diagnosis. However, former smokers can share these survival benefits as it is not “too late” for patients that were smokers prior to their lung cancer diagnosis.  

 

“These data highlight that smoking cessation continues to be a critical part of patient care for our patients with a smoking history,” explained Dr. Nicholas C. Rochs. “It is not surprising to see that the short-term benefits are more striking in those with heavier smoking histories, but we also see a trend towards improved survival even in lighter smokers who quit more recently.  

 

Researchers found that the benefit of quitting smoking was also slightly greater among patients who smoked at least 20 cigarettes per day for over 30 years. These patients who smoked 20 cigarettes a day for at least a year were defined as heavy smokers, and researchers found that long-term heavy smokers who also quit smoking less than two years before, between two and five years before, and for more than five years before their lung cancer diagnosis had a 14%, 17% and 22% reduced risks of death from all causes compared to non-smokers. However, for those who smoked less than 30 pack-years (the clinical qualification to measure a patient’s experience with smoking), the reduction rate was only significant for those that quit smoking at least five years before their lung cancer diagnosis.  

 

“We know that lung cancer patients who quit smoking can improve their health by reducing surgical complications and side effects from treatments as well as improving overall objective and subjective quality of life,” explained Rochs, Assistant Professor of Medicine, Hematology and Medical Oncology at The Tisch Cancer Institute at Mount Sinai. 

 

In a press briefing of the study, Fares explained that they want to use the time of a lung cancer screening to explain to patients the benefits of smoking cessation and showing patients that there is a marked survival benefit. Moreover, researchers found that the overall survival advantage of quitting smoking prior to their lung cancer diagnosis occurred in all subsets of patients studied including sex, lung cancer stage, histology and a patient’s pack years. Fares summed up the study as “it’s never too late to quit smoking” imploring oncologists to explain this to their patients.