Cancer patients who quit smoking had a two-year survival rate of about 85%, compared with 74% for those who kept smoking.
Among patients with advanced-stage (stage III/IV) cancer who smoked, those who quit reached 85% survival at ~540 days versus ~210 days for those who didn’t quit — nearly a full year of extra life.
Only about one in five smokers in the study managed to quit within six months of their initial oncology visit, highlighting the challenge and the need for integrated cessation support.
When someone is diagnosed with cancer, it’s easy to feel that smoking cessation might no longer make a meaningful difference.
However, recent research from Washington University School of Medicine and Siteman Cancer Center shows that this isn’t the case.
Across cancer types and stages, patients who stopped smoking after beginning cancer care went on to live significantly longer than those who continued.
The takeaway? It’s never too late to quit, and doing so can meaningfully improve survival.
“By showing that it’s never too late, even for the sickest patients, we hope to inspire all cancer centers and patients to include smoking cessation support as part of routine cancer care to improve survival,” researcher Li-Shiun Chen, M.D., said in a news release.
The study
The research team conducted an observational study involving 13,282 adults receiving outpatient oncology care at Siteman.
At their first visit, smoking status was recorded and patients who reported smoking were observed over the next six months to see whether they quit. About 1,725 participants identified as current smokers at that initial visit.
The primary outcome: overall survival (OS) over the next two years. The study tracked who quit within six months and compared survival outcomes between those who quit and those who kept smoking. They also looked across cancer stages (stage I/II vs. III/IV) and cancer types.
A key feature: the cessation program was integrated into cancer care through electronic health record tools and on-site support (counselling, apps, medications) at Siteman.
The results
The survival advantage for those who quit was clear. Among all cancer patients in the study, two-year survival was about 85% for quitters compared to 74% for those who continued smoking.
For patients with advanced stage (III/IV) cancer, the difference was especially striking: 85% of quitters were alive at ~540 days, whereas those who kept smoking reached that 85% survival mark only at ~210 days. That’s nearly one additional year of life on average.
Bottom line: For anyone diagnosed with cancer who smokes, this study sends a clear message: quitting matters—no matter how far along the diagnosis. Quitting smoking isn’t just a quality-of-life decision, it may extend survival in meaningful ways.
“Advanced-stage cancer patients often feel hopeless,” researcher Steven Tohmasi, M.D. said in the news release. “If they feel they have limited time, some doctors might not actively encourage patients to quit smoking or may prioritize patient comfort over cessation efforts.
“But when we’ve shown patients our data, it gives them hope and motivates them to want to quit. An extra year of life is a long time for patients who may have been told they only had months to live.”