Even for the Sickest Cancer Patients, Quitting Smoking Can Add a Year to Life

Quitting smoking after a cancer diagnosis dramatically extends survival, even for advanced cases.

When you already have cancer, quitting smoking can feel pointless. The damage is done, right? But new research from Washington University School of Medicine in St. Louis says that’s wrong — profoundly wrong.

Even for people with late-stage cancer, putting out that last cigarette could buy nearly a year of life, according to a new study that followed more than 13,000 cancer patients treated at the Alvin J. Siteman Cancer Center. Among them, about one in four were smokers when they started treatment. And for those who managed to quit, the rewards were striking. Their odds of surviving two years were 85%, compared to 74% among those who kept smoking.

In late-stage cancers — where patients are often told to prepare for the end — quitting smoking more than doubled survival time.

“If they feel they have limited time, some doctors might not actively encourage patients to quit smoking,” said Dr. Steven Tohmasi, the study’s first author.

“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.”

The Fourth Pillar of Cancer Care

Siteman’s approach can be described as plain common sense: treat quitting smoking as seriously as chemotherapy or radiation. Dr. Li-Shiun Chen, the study’s senior author, calls it “the fourth pillar of cancer treatment.”

“WashU Medicine and Siteman are the leading frontier to ensure every cancer patient is offered tobacco treatment as part of their cancer care, using a novel, informatics-enabled, point-of-care model,” Chen said. “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.”

Chen’s team developed a system called ELEVATE — short for Electronic Health Record–Enabled Evidence-Based Smoking Cessation Treatment. It automatically flags patients who smoke, prompting clinicians to offer help on the spot, which entails everything from nicotine-replacement therapy to text-based counseling.

Before ELEVATE, quitting support often fell through the cracks. Doctors and nurses were too focused on tumor scans and drug regimens to talk about smoking. But now, those conversations happen as a normal part of cancer care.

Rethinking What’s “Too Late”

The numbers behind this study are both sobering and empowering. Out of 13,282 patients treated between June and December 2018, 1,725 were active smokers. Only 22% of them quit within six months — but those who did had nearly double the survival odds. After adjusting for age, sex, cancer type, and disease stage, continuing smokers had a 97% higher risk of death than those who quit.

This matters because, as the authors note, smoking cessation has long been underused in oncology clinics, despite decades of evidence that it improves recovery, treatment response, and overall health.

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“Smoking increased the risk of mortality among cancer survivors, even after adjusting for cancer type and stage,” the researchers wrote in their new study. “Smoking cessation is associated with reduced mortality risk among cancer survivors, even when initiated after diagnosis or in patients with advanced-stage disease.”

For many oncologists, smoking cessation simply hasn’t been a top priority. Some assume it’s futile for patients with advanced disease. Others focus on immediate comfort. After all, cancer and the invasive treatments that commonly come with it are stressful enough. But that mindset may be costing patients precious months.

“There’s this fatalistic idea that if someone already has stage IV cancer, there’s no point in changing lifestyle habits,” Chen explained. “Our data challenge that. Even if you’re diagnosed late, quitting helps — not just in theory, but in measurable, lifesaving ways.”

The mechanisms of lifespan extension aren’t mysterious. Quitting smoking improves oxygen delivery, boosts immune function, and reduces treatment complications. It also lowers the risk of secondary cancers and improves tolerance to chemotherapy. In short: cancer therapies simply work better when the body isn’t constantly being poisoned.

Scaling Up the Future of Care

The program’s success has inspired expansion. Fourteen partner clinics across Missouri and Illinois have adopted the model, and in September 2025, Chen’s team launched a $1.6 million National Cancer Institute–funded clinical trial to test how such programs can scale nationwide. The trial spans eight states and includes research hubs at Washington University, Vanderbilt, Penn, and the St. Louis VA Medical Center.

Nationally, the project is spreading through EpicShare, a digital platform that connects healthcare systems using the same electronic records software. Chen and colleagues say this is the key to making smoking cessation routine everywhere — not an optional add-on, but a built-in reflex of good care.

As Tohmasi put it, “We hope this study sends a clear message: it’s never too late to quit.”

The findings appeared in the Journal of the National Comprehensive Cancer Network.