Smoking Cessation Before a Lung Cancer Diagnosis Improves Outcomes

Aline Fusco Fares, MD

People who quit smoking at any time, even up to 2 years before a lung cancer diagnosis, have increased chances of survival after their diagnosis, according to data during a 2020 ASCO Virtual Scientific Program press briefing.

Researchers 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. Researchers found that individuals who quit smoking more than 5 years before their lung cancer diagnosis had a 20% reduced risk of death from all causes, those who quit between 2 to 5 years prior to their diagnosis had a 16% reduced risk of death and those 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 Aline Fusco Fares, MD, lead author of the study and a clinical research fellow at the Princess Margaret Cancer Centre in Toronto. "The study's message is simple: quit smoking now."

In the study, researchers confirmed that there is a better overall survival among lung cancer patients who never smoked compared to those that did. 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.

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 2 years before, between 2 to 5 years before, and for more than 5 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 that smoked less than 30 pack-years, the reduction rate was only significant for those that quit smoking at least 5 years before their lung cancer diagnosis.

"We saw a slightly bigger benefit to quitting among people who had smoked heavily for over 30 years compared with the overall population of former smokers. For long-term smokers, the benefits of quitting cannot be overstated," Geoffrey Liu, MD, MSc, a clinician scientist at the Princess Margaret Cancer Centre in Toronto and senior author on the study, said in a press release.

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.

Reference

Fares A. Smoking Cessation and Lung Cancer outcomes: A survival benefit for recent quitters? A pooled analysis of 35,481 International Lung Cancer Consortium (ICLO) patients. Presented at: 2020 ASCO Virtual Scientific Program; May 12, 2020. Abstract 1512.