New research suggests that excess abdominal fat impairs the lung’s immune defenses, allowing non-small cell lung cancer to develop more rapidly.
RT’s Three Key Takeaways:
- Abdominal Fat Predictor: Researchers found that total fat area in the abdominal region is a more accurate marker for lung cancer risk than body mass index, according to a study of 1,170 current and former smokers.
- Suppressed Immune Defense: The study demonstrated that obesity increases regulatory T cells in the lungs, which impairs the ability of the immune system to attack developing tumors.
- Clinical Implications: Understanding how excess fat undermines airway immunity could lead to new interventions for preventing or intercepting lung cancer in high-risk individuals.
Researchers have documented evidence that excess abdominal fat increases the risk of developing non-small cell lung cancer (NSCLC) by undermining the immune system’s response, according to a study published in the Journal of Thoracic Oncology.
The findings by researchers at Roswell Park Comprehensive Cancer Center show that the immune system’s ability to attack developing tumors is compromised in obese patients. This contradicts earlier research suggesting that patients with a high body mass index (BMI) might face a lower risk for the disease.
The study analyzed data from 1,170 current or former smokers, including 576 individuals diagnosed with stage 1 or 2 NSCLC and 576 people in a screening control group. Researchers used CT scans to measure the total fat area (TFA) in the abdominal region, which they identified as a more physiologically meaningful definer of obesity than BMI. The data showed that individuals in the control group with higher TFA were more likely to develop lung cancer later.
“Our results provide strong evidence that obesity is a risk factor driving lung cancer development and that strategies to correct the effects of obesity on airway immune cells may help us to prevent or intercept early-stage lung cancers in people at high risk of developing lung cancer,” said Sai Yendamuri, chair of thoracic surgery, in a news release.
In laboratory and human patient examinations, the researchers found that the lungs of obese subjects contained higher numbers of regulatory T cells, also known as tregs. These cells appeared to allow lung cancer to grow unchecked, while other immune cells capable of killing tumor cells were defective. Preclinical models with excess fat were shown to develop lung tumors faster as a result.
“Now we know that obesity impairs the lung’s immune defenses before and during the early stages of tumor development,” said Joseph Barbi, assistant professor of oncology in the department of immunology, in a news release.
While obesity is known to increase the risk of at least 13 different types of cancer, its role in lung cancer has historically been less clear. The study authors noted that clarifying this link is vital for public healthcare, as the percentage of the US population with a BMI over 25 has increased to 66% over the last 40 years.
The research was supported by grants from the National Cancer Institute (NCI), the Roswell Park Alliance Foundation, and the American Lung Association. The team is now working to identify other mechanisms through which obesity compromises the immune defenses of the lung.
