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In a retrospective study reported at , the American College of Chest Physicians annual meeting, of the nearly 7,500 patients in the VA health system who were listed as current or former smokers just before undergoing surgery for stage I lung cancer, roughly -- or smoking again -- a year later.

In this exclusive 番茄社区 video, study author Brendan Heiden, MD, of Washington University School of Medicine in St. Louis, presents the study details.

Following is a transcript of his remarks:

Non-small cell lung cancer is the leading cause of cancer-related mortality in the United States, with 80% to 90% of cases caused by cigarette smoking. The gold-standard treatment for early-stage lung cancer remains surgery. Previous studies have demonstrated that smoking at the time of surgery is associated with significantly higher risk of perioperative morbidity and poor long-term outcomes. For this reason, several organizations, including the World Health Organization, recommend smoking cessation at least 4 weeks prior to surgery.

While smoking habits are well documented in lung cancer patients at the time of diagnosis, it is unclear what proportion of these patients continued to smoke following surgery and how this affects long-term outcomes.

We performed this retrospective cohort study using a uniquely compiled dataset from the Veterans Health Administration of adults with clinical stage I non-small cell lung cancer undergoing surgery from 2006 to 2016. This dataset was assembled and groomed through chart review by a large team of dedicated researchers at the VA.

Our main exposure of interest was smoking status, which we assessed 1 year after surgery and defined as persistent smoking. We then assessed the relationship between persistent smoking and disease-free survival and overall survival.

Contour diagram for our study is shown on the left. Our initial cohort included over 10,000 veterans. We had several exclusion criteria, including never-smokers, patients with pathologic stage IV disease, patients who died within 30 days of surgery, and patients who did not follow up within the VA. This left a final study cohort of roughly 7,500 patients.

Various demographics from our study population are shown on the right side of this slide. And it's a relatively representative cohort of veterans. The mean age is 67 years old. The majority of the cohort is male. Sixty percent of patients were actively smoking at the time of surgery, and the median Charlson Comorbidity score was seven, which is substantially higher than what would be expected in the general U.S. population.

The left side of this slide shows important treatment characteristics. As you can see, the median time between diagnosis and surgery was 62 days, with 30% of veterans experiencing a treatment delay beyond 12 weeks. The majority of veterans underwent lobectomy, as would be expected in this population. And the most common surgical approach was open thoracotomy.

Now, focusing on the right side of the slide, you'll see that a majority of patients had pathologic stage I disease. The most common postoperative complication was pneumonia. And finally, the 30-day readmission rate was 7%.

This slide shows the relative smoking rates at the time of surgery and 1 year after surgery. On the left side, you can see that roughly 60% of the population was smoking at the time of surgery. In the middle, 1 year after surgery, 58% of these individuals continued to smoke. Additionally, of the 39% of patients who were former smokers at the time of surgery, 20% relapsed and started smoking again 1 year after surgery. Overall, roughly 45% of the entire population was found to persistently smoke at 1 year after surgery.

The median follow-up in our cohort was 6.6 years. As you can see on the left side of this slide, persistent smoking was associated with significantly shorter overall survival, with an adjusted hazard ratio of all-cause mortality of 1.29. The median survival was 82.2 months in those who were not smoking compared to 73.7 months in persistent smokers. A cumulative incidence function for recurrence is shown on the right. Recurrence was detected in roughly 25% of patients. We did not find an association between persistent smoking and disease recurrence, however.

So, in conclusion, we found that a majority of veterans smoke at the time of lung cancer diagnosis. One year following surgery a significant proportion of this population persistently smokes. Persistent smoking is associated with significantly worse overall survival, but is not associated with disease recurrence. Cancer survivorship programs should continue to focus on smoking cessation, given the disproportionate impact of persistent smoking on early-stage lung cancer surgery following curative-intent treatment.

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