Nasal swab could help diagnose lung cancer

In the case of patients with low risk of lung cancer, the current diagnostic procedure can sometimes be invasive and unnecessary. However, new research may have uncovered a less invasive, less costly way to screen these patients.

A team of researchers from Boston University School of Medicine (BUSM) in Massachusetts may have found a more convenient way to determine whether lung lesions are malignant. The findings were published in the Journal of the National Cancer Institute.

Lung lesions – or solitary pulmonary nodules – are small growths in the lungs that are usually detected incidentally when a patient has an X-ray for other reasons. Although physicians are typically worried about cancer upon discovering the lesions, these are benign in the majority of cases.

For instance, of all the patients screened using computed tomography (CT) as part of the National Lung Cancer Screening Trial, 25 percent had a lung lesion, but approximately 95 percent of these cases were, in the end, found to be benign.

As the authors of the new study point out, many of the patients who ultimately receive a benign diagnosis undergo invasive medical procedures such as surgical lung biopsy. The new research, however, uncovers a genomic tool that could enable physicians to tell whether a patient has a malignant lesion by simply taking a swab of their nose.

BUSM researchers collected nasal epithelial brushings from patients who were in the process of having their lung lesions evaluated. These participants were people who currently and formerly smoked, and who were enrolled in the two Airway Epithelium Gene Expression in the Diagnosis of Lung Cancer clinical trials.

The epithelium is a membrane of cellular tissue that, in this case, encloses and protects the nasal cavity. Scientists examined these nasal epithelial brushings and profiled the participants’ gene expression by using microarrays – a genetic tool commonly used to detect gene mutations, such as in BRCA1 or BRCA2, in a person’s DNA.

The researchers found cancer-associated gene expressions to be altered in a similar way across the two airway sites. This led them to believe that the nasal airway epithelial field in people who smoke extends all the way to the nose, and that the brushings could be a biomarker for lung cancer.

Marc Lenburg, Ph.D., a professor of medicine at BUSM and co-senior author of the study, explains the significance of the findings:

“Our findings clearly demonstrate the existence of a cancer-associated airway field of injury that also can be measured in nasal epithelium. We find that nasal gene expression contains information about the presence of cancer that is independent of standard clinical risk factors, suggesting that nasal epithelial gene expression might aid in lung cancer detection. Moreover, the nasal samples can be collected non-invasively with little instrumentation or advanced training.”

Corresponding author Dr. Avrum Spira, a professor of medicine, pathology, and bioinformatics at BUSM, also weighs in:

“There is a clear and growing need to develop additional diagnostic approaches for evaluating pulmonary lesions to determine which patients should undergo CT surveillance or invasive biopsy,” Dr. Spira says. The ability to test for molecular changes in this ‘field of injury’ allows us to rule out the disease earlier without invasive procedures.”

This research builds on previous work by the same team, who located another biomarker for lung cancer, found in the epithelium of the bronchus.

“Our group previously derived and validated a bronchial epithelial gene-expression biomarker to detect lung cancer in current and former smokers,” Dr. Spira explains. “This innovation […] is measurably improving lung cancer diagnosis. Given that bronchial and nasal epithelial gene expressions are similarly altered by cigarette smoke exposure, we sought to determine in this study if cancer-associated gene expression might also be detectable in the more readily accessible nasal epithelium.”