Emphysema does not directly cause lung cancer, but it significantly increases the risk. People with emphysema are roughly 3 to 4 times more likely to develop lung cancer than those without it, even after accounting for smoking history. This means emphysema itself, independent of how much someone has smoked, acts as a risk factor for lung cancer.
The relationship is strong enough that researchers now consider emphysema a standalone predictor of lung cancer. Understanding why requires looking at what emphysema does to lung tissue over time and how that damage creates conditions where cancer is more likely to take hold.
How Much Emphysema Raises Lung Cancer Risk
A CT-based study published in Cancer Prevention Research found that people with at least 5% emphysema visible on a chest scan had a 3.8-fold increased risk of lung cancer compared to controls, after adjusting for pack-years of smoking, family history, and other lung diseases. Even any detectable emphysema (greater than 0%) raised the risk 2.79-fold. These numbers held up across multiple statistical models, all with high confidence.
Certain groups faced even steeper odds. Smokers under 65 with emphysema had a 4.64-fold increased risk. Heavy smokers with 40 or more pack-years and emphysema had a 4.46-fold increase. The risk of small-cell lung cancer specifically was 5.62 times higher in people with emphysema.
A 2025 meta-analysis pooling data from multiple studies confirmed a dose-response pattern: mild emphysema carried an overall odds ratio of 3.66 for lung cancer, while moderate to severe emphysema pushed that to 4.66. In plain terms, the worse the emphysema, the higher the cancer risk, though the relationship levels off somewhat at more advanced stages.
In a large study of over 2,500 patients with COPD (the broader disease category that includes emphysema), 8.5% developed lung cancer during follow-up, at a rate of about 17 cases per 1,000 person-years. That’s a substantially higher rate than in the general population.
Why Damaged Lungs Are Vulnerable to Cancer
The connection between emphysema and cancer isn’t coincidental. Several biological processes link the two, and they go well beyond the shared risk factor of cigarette smoke.
Chronic inflammation is the central driver. Emphysema involves ongoing destruction of the tiny air sacs in the lungs, and the body’s inflammatory response to that damage never fully resolves. Immune cells flood into the lungs and release signaling molecules that, over time, promote the kind of cellular changes that lead to cancer. One key pathway involves a molecular switch called NF-κB, which ramps up the production of inflammatory signals, growth factors for new blood vessels, and proteins that help tumors spread. These same molecules are active in both emphysema and lung cancer.
Oxidative stress plays a compounding role. The lungs of people with emphysema are under constant assault from reactive oxygen molecules, whether from cigarette smoke, air pollution, or the inflammatory process itself. This oxidative damage harms DNA directly and disrupts the normal cycle of cell growth and death. Cells begin to multiply faster than they should, and damaged DNA that would normally trigger cell death instead gets passed along. Over time, this tips the balance toward uncontrolled growth.
There’s also a process called epithelial-to-mesenchymal transition, where the cells lining the airways begin to change their identity and behavior. Repeated cycles of lung injury and repair accelerate this shift, increasing the chance of genetic errors accumulating with each round of cell turnover. The progression from normal tissue to overgrown tissue to cancerous tissue becomes more likely in lungs that are constantly trying to heal themselves.
Shared Genetic Susceptibility
Some people may be genetically predisposed to developing both emphysema and lung cancer. Genome-wide association studies have identified several chromosomal regions linked to both conditions. The most studied is a region on chromosome 15 (called CHRNA3/5), which affects nicotine receptors and has been associated with increased susceptibility to both COPD and lung cancer.
Other genetic regions work in the opposite direction. Variants in genes called HHIP and FAM13A appear to protect against both conditions simultaneously. This shared genetic architecture suggests that emphysema and lung cancer aren’t just linked by environmental exposures like smoking. For some individuals, the same inherited vulnerabilities make them susceptible to both diseases, which helps explain why some smokers get emphysema and cancer while others get neither.
What About Non-Smokers?
While smoking is by far the most common cause of both emphysema and lung cancer, the two conditions can occur in people who have never smoked. Between 15 and 20 percent of men with lung cancer are non-smokers, and the figure is over 50 percent for women globally. Underlying lung disease, including emphysema from occupational exposures, air pollution, or genetic conditions like alpha-1 antitrypsin deficiency, is recognized as a risk factor for lung cancer in non-smokers.
The exact size of that risk in non-smokers is harder to pin down because most emphysema research focuses on smoking populations. But the biological mechanisms linking chronic lung inflammation to cancer don’t depend on cigarette smoke. Any cause of sustained lung damage and inflammation could theoretically promote the same cascade of cellular changes.
How Emphysema Affects Cancer Outcomes
Having emphysema alongside lung cancer also makes treatment harder and survival worse. Respiratory conditions are the most common comorbidity in lung cancer patients, affecting about 36% of those diagnosed. A large analysis found that having even one additional chronic condition raised the risk of death by 33%. Patients with a cluster of cardiovascular, respiratory, and metabolic conditions faced a 74% higher risk of death compared to those without comorbidities.
The practical reasons are straightforward. Emphysema reduces lung function, which limits surgical options. Removing a tumor often means removing a section of lung, and patients who already have compromised breathing capacity may not tolerate that loss. Severe emphysema is specifically associated with worse survival after lung cancer surgery, particularly in men and in those with squamous-cell carcinomas.
Lung cancer in patients with emphysema also tends to be diagnosed later. Symptoms like shortness of breath and coughing overlap heavily between the two conditions, making it easy to attribute new or worsening symptoms to emphysema rather than investigating for cancer. This is one reason screening CT scans are recommended for high-risk individuals, as they can catch tumors early in lungs already damaged by emphysema.