By Drs. David Niesel and Norbert Herzog
Any cancer patient will tell you that the fear of a cancer's recurrence is with them all the time. For many, follow-up can involve invasive or uncomfortable testing that serves as an ongoing reminder of cancer's threat. For patients with lung cancer, the follow-up usually means regular CT scans to look for tumors. Now there is a promising new breath test that detects the presence of certain markers that are only present in patients with lung cancer. How is that for patient friendly?
Lung cancer is the leading cause of cancer deaths in every ethnic group. It is estimated that in 2016, 224,000 new cases will be been diagnosed representing almost 14 percent of all new cancers. The leading cause of lung cancer is smoking. Only 15 percent of lung cancer patients are diagnosed before the disease has spread or metastasized. Deaths from lung cancer are estimated to be 158,000 in 2016. Sadly, only about 18 percent of people diagnosed with lung cancer survive 5 years. Survival time is dependent upon the stage at which the cancer is diagnosed. So the need for better screening tests to identify lung cancer as early as possible are needed along with tests that could detect its recurrence.
Scientists used a device called a mass spectrometer to detect the presence and amounts of specific volatile organic compounds, or VOCs, in the breath of cancer patients. These compounds are generally in very low amounts in the body but exhaled breath contains thousands of them. The carbonyls have been found to be a signature for lung cancer.
This breath signature has been used as the primary screening tool to detect the recurrence of lung cancer. A patient's breath is air exposed to a quarter-sized microchip that captures VOCs present in the breath. A mass spectrometer identifies and determines the level of these the chemicals in the breath in just a few hours for about $20. Currently, screening for the recurrence of lung cancer by low dose CT scans costs between $350 - $400 out-of-pocket. An earlier study showed that these CT scans only increased survival by 6.7 percent in patients of high risk for lung cancer and mortality was reduced by 20 percent. A large national study of CT scan screening showed an astounding 94 percent were false positives. False positive results lead to additional testing that includes some invasive procedures.
In the current study, the VOCs of 31 patients with lung cancers were compared before and after their tumors had been surgically removed to 187 control patients with no history of cancer. Previous studies have reported elevated levels of four distinct carbonyl cancer VOCs in cancer patients that were different from patients with benign lung disease or no disease. VOCs were decreased after surgery with three of the four VOCs at levels comparable to those in the control patients. Given the high rate of false positives, the relatively high cost, the increased exposure to CT radiation and the challenge of getting patients to comply makes finding an alternative screening method a worthy goal. This study was preliminary, so studies with many more patients will have to be conducted before this new approach can be the standard screening for lung cancer recurrence.
Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.