Lung cancer: Is it ever too late to quit smoking?

Naveed Saleh, MD, MS, for MDLinx | March 04, 2019

Smokers with non-small cell lung cancer (NSCLC) may have decreased 12-month survival compared with patients who quit smoking or never smoked, according to a recent study published in Lung Cancer.


In total, 23% of smokers ceased smoking within 3 months of NSCLC diagnosis. Furthermore, 69% of those who quit smoking were alive at 1 year vs 53% of those who kept smoking.

“This is the largest prospective study that validates smoking in NSCLC,” wrote authors, led by Rachel E. Gemine, Clinical Research Centre, Prince Philip Hospital, Llanelli, UK. “It shows a third of people are smoking at the time of diagnosis.”

The investigators conducted this longitudinal study to determine whether smoking status at baseline and quitting are independently correlated with 1-year survival via an analysis of a cohort of 1,124 patients with newly diagnosed NSCLC.

Smoking status was checked at diagnosis and at every subsequent routine or emergency hospital visit. Patients were offered guideline-based cancer treatments and smoking cessation treatments per local availability.

At 1 year, 57% of current smokers, 60% of ex-smokers, and 77% of never-smokers were alive (P=0.01).

After controlling for variables—including age, stage, surgery, and sex—former smokers (adjusted HR [aHR]: 1.96; CI, 1.16–2.31) and current smokers (aHR: 2.04; CI, 1.19–3.48) were found to have higher odds of dying within 1 year of initial diagnosis vs never-smokers.

In total, 23% of smokers ceased smoking within 3 months of NSCLC diagnosis. Furthermore, 69% of those who quit smoking were alive at 1 year vs 53% of those who kept smoking (P < 0.01).

Most smokers with lung cancer claimed that they were motivated to stop smoking, with even a single session with a smoking-cessation specialist being effective—leading to 22% of patients observing abstinence at 6 months vs 14% among a general population of smokers offered the same intervention.

Importantly, the authors wrote that any advantage linked to smoking cessation can have significant effects. Thus, it may be a good idea to consider the cost effectiveness of specialized cessation programs for those with lung cancer.

Other research supports the hypothesis that patients with lung cancer who smoke are more likely to die sooner. In some observational studies involving patients receiving surgery for NSCLC, smokers were found to have increased rates of local cancer recurrence, secondary cancers, complications, and death. Furthermore, smokers with NSCLC who received radiotherapy experienced lower quality of life, more complications, increased second primary cancers, and higher mortality.

Continued smoking after a cancer diagnosis sustains carcinogen exposure, which contributes to secondary cancers and dampens the immune system’s response to tumor cells, as well as chemoresistance. Additionally, smoking accelerates the metabolism by triggering cytochrome 450, which results in increased clearance of chemotherapy drugs.

The authors of this observational study acknowledged that other covariates could have influenced their results, including better medication adherence, healthier diet, and exercise. Moreover, lower socioeconomic status is known to impact mortality in cancer patients. Notably, the investigators recruited few inpatient or emergency patients.

“Quitting smoking was associated with 25% reduction in mortality which may be clinically important although not statistically significant, after adjusting for other factors,” concluded the authors.