Lung cancer is the most common cancer in the world. And its main cause is smoking.
We could say that it is a very treacherous cancer, as it does not usually produce symptoms until it is very advanced. For this reason, a person, usually a smoker, may suddenly find out that they have lung cancer, with the resulting psychological trauma and family and social drama that this entails.
That is why it is so important to improve the means of detecting this type of cancer.
As of July 2016, there are no tests or screenings that meet the necessary requirements to be considered for the early diagnosis of lung cancer in the general population.
The Spanish Association Against Cancer (AECC), speaking about lung cancer, points out that after reviewing the patient's medical history and performing a physical examination, a series of routine tests are carried out :
At our clinic, through research carried out at Biosalud Análisis, we have created a test, Cancertest® Lung, which allows us to determine the stratified risk of lung cancer in smokers and people who have smoked in the last 10 years. Given the lack of early detection tests in general, we recommend that you request this test.
However, science continues to investigate ways and means to detect lung cancer better and earlier. In June 2015, the US National Cancer Institute reported on pioneering research into the effectiveness of a test consisting of a genetic classifier of upper respiratory tract cells.
Assessing gene expression in normal upper airway cells of current and former smokers with suspected lung cancer may be useful in improving the diagnostic accuracy of bronchoscopy, potentially reducing the need for invasive biopsies, according to a new study published in the New England Journal of Medicine (NEJM).
When potentially cancerous lesions are identified in the lungs using computed tomography, doctors often use bronchoscopy to evaluate these lesions more closely. Although this procedure is relatively safe, it often fails to produce a definitive diagnosis because it cannot reach some areas of the lung. In such cases, an invasive biopsy (surgical or needle) may be necessary. However, these procedures carry a risk of complications, and some researchers have reported that more than a quarter of people who undergo a lung biopsy are found to have benign lesions.
In an effort to help solve this problem, researchers examined normal bronchial cells in the upper airway, drawing on the concept of a "field of injury," explained the study's principal investigator, Avrum Spira, MD, of Boston University School of Medicine. When a person smokes, all the cells in their airways are exposed to tobacco smoke, causing DNA damage. Dr. Spira and his colleagues demonstrated in a 2007 study that there is a distinct pattern of DNA damage in the epithelial cells of smokers who go on to develop lung cancer.
Based on differences in DNA damage patterns, researchers developed a distinctive genetic expression—a genomic classifier—that could be used to examine normal bronchial airway cells obtained during bronchoscopy to detect the presence of tumors in the lungs. In the NEJM study, they applied the findings from the previous study and demonstrated that "the classifier works in the real world, in a clinical setting," Dr. Spira said.
The study, which was funded in part by the NCI Early Detection Research Network, enrolled 639 adult smokers and former smokers who were participating in two clinical trials, AEGIS 1 and AEGIS 2. All participants underwent bronchoscopy for suspected lung cancer, and a brush was used to collect epithelial cells from the main bronchi of the airways during bronchoscopy. Gene expression patterns in the epithelial cells were analyzed, and patients were followed until a diagnosis was made or for 12 months after bronchoscopy. A total of 487 patients were found to have lung cancer.
No diagnosis could be made in 272 patients based on bronchoscopy alone. Of these patients with non-diagnostic bronchoscopy, 170 underwent an invasive procedure to confirm a diagnosis (including surgery in 76 patients), 52 of whom were ultimately diagnosed with benign lung lesions.
They also evaluated the sensitivity and specificity of bronchoscopy plus the classifier, since an accurate diagnostic test not only detects most cancers that are present (sensitivity), but also has a low chance of incorrectly indicating cancer in a person who does not have it (specificity).
Overall, the sensitivity of bronchoscopy plus the classifier was 97 percent compared to 75 percent for bronchoscopy alone. The sensitivity of the combined test was consistently high for nodule size, location, cancer stage, or type, they reported.
The genomic classifier incorrectly suggested cancer in 53 percent of people who did not have lung cancer. Although the test has a high false positive rate, when both the bronchoscopy and the classifier are negative, the likelihood that the patient has cancer is reduced.
A negative result can inform clinical management and eliminate unnecessary invasive biopsies that carry the risk of complications, as well as costs to the healthcare system, Dr. Spira said. It is ultimately "a negative test that provides peace of mind," he explained.
Initially, the test—known commercially as the Percepta Bronchial Genomic Classifier—will be available at 30 to 40 medical centers as part of an early access program before it becomes more widely available, according to Veracyte, which manufactures the test.
