Two new approaches to help diagnose lung cancer could enable doctors to determine which patients need surgery, which is often highly invasive and potentially dangerous. Researchers at Vanderbilt University have identified a set of molecular biomarkers, some found in blood and some in biopsied tissue, that improved the accuracy of lung-cancer diagnosis in tissue and blood samples from patients whose diagnosis had already been confirmed with surgery. Larger clinical trials of the biomarkers are now needed to determine the power of the tests to diagnose patients whose lung-cancer status is not yet known.
Lung cancer presents a serious challenge to oncologists. While it is responsible for the greatest number of cancer-related deaths in the United States–there are approximately 215,020 new cases per year and 161,840 deaths–“there is no screening and no early-detection tools validated to reduce mortality,” says David Carbone, an oncologist at the Vanderbilt-Ingram Cancer Center, in Nashville, TN. By the time symptoms appear, the cancer is usually at an advanced stage and very difficult to treat. “If we could change those ratios slightly, we’re talking about saving 10,000, 20,000, maybe 50,000 lives,” says Carbone.
To diagnose lung cancer, patients typically undergo x-ray or CT scans to detect abnormal growths on the lungs. However, highly sensitive CT scans can detect small nodules that may or may not be cancerous. Physicians must then decide whether to send the patient for surgery, which often involves cutting open the chest, or take a more conservative approach and recommend another scan in six months. A recent study found that as many as one in five people diagnosed with lung cancer did not in fact have it and underwent surgery unnecessarily.
This issue may soon become an even bigger problem. In an attempt to diagnose lung cancer earlier, a large nationwide study is under way to determine if screening heavy smokers with CT scans can reduce death rates. “If studies show that early CT scanning can help find cancers earlier, then more and more patients will come into doctor’s offices with difficult to interpret scans,” says Pierre Massion, a pulmonary physician at Vanderbilt. “CT scans can give lots of false positives, so we need a companion test that is highly specific.”