Even after a lung cancer diagnosis, quitting smoking can prolong life and lower the risk of disease progression, a prospective study found.
Between 2007 and 2016, researchers at one center in Moscow, Russia, recruited 517 current smokers who were diagnosed with early-stage (IA to IIIA) non-small-cell lung cancer. Current smokers were defined as individuals who had been smoking at least one cigarette per day for more than one year before the time of diagnosis. During annual follow-up visits through 2020, they were categorized as having quit smoking if they reported having quit completely; otherwise, they were categorized as having continued smoking. Outcomes included overall survival, progression-free survival, and all-cause and lung cancer-specific mortality. Results were published July 27 by Annals of Internal Medicine.
During an average of seven years of follow-up, 220 (42.5%) participants reported that they had quit smoking, including eight who resumed smoking during follow-up, and 297 (57.4%) reported that they continued smoking after their diagnosis. Of the 220 patients who quit smoking, 157 (71.3%) quit shortly after diagnosis and before the time of receiving the first treatment, and 33 (15%) quit after treatment initiation but during the first year of diagnosis. Thirty (13.6%) patients quit after the first year of diagnosis. During follow-up, there were 325 (63.8%) deaths, 271 (53.2%) cancer-specific deaths, and 172 (33.7%) cases of tumor progression (i.e., local recurrence or metastasis).
The adjusted median overall survival time was 21.6 months longer among patients who had quit smoking than those who continued smoking (6.6 vs. 4.8 years, respectively; P=0.001). Compared with patients who continued smoking, those who quit had higher five-year overall survival (48.6% vs. 60.6%; P=0.001) and progression-free survival (43.8% vs. 54.4%; P=0.004). In adjusted analyses, smoking cessation remained associated with decreased risk for all-cause mortality (hazard ratio [HR], 0.67; 95% CI, 0.53 to 0.85), cancer-specific mortality (HR, 0.75; 95% CI, 0.58 to 0.98), and disease progression (HR, 0.72; 95% CI, 0.56 to 0.92). The protective effects of smoking cessation were observed across all subgroups, including mild to moderate and heavy smokers, patients with earlier and later tumor stages, and those who received or did not receive chemotherapy or radiation therapy. Among other limitations, some misclassification of primary cause of death and tumor progression status is inevitable, the study authors noted. They added that smoking status was based on self-report.
The results strengthen the case for implementing tobacco cessation treatment as part of routine health care for all patients with cancer, an accompanying editorial noted. “Tobacco cessation treatment must extend beyond large cancer centers to reach community cancer centers, community health centers, lung cancer screening sites, and other settings in which people receive cancer diagnoses and treatment,” the editorialist wrote. “It is not too late for cigarette smokers with cancer and cancer survivors to benefit from becoming smoke-free. We need to make this happen!”