The management of lung cancer, which in many cases is a deadly disease, is likely to change in the near future as the field adopts new strategies for diagnosis and treatment. A more fine-grained and stepwise approach to screening, and pharmaceutical and surgical innovations could help to fight the disease.
The Challenge of False Positive Screening Results
Low dose CT (LDCT) screening could, via earlier detection, provide an advantage over traditional chest X-rays and thus help reduce mortality. One drawback, however, concerns false positive results. These occur when “suspicious” nodules are detected in a patient’s lung, but he or she does not have lung cancer and instead the nodule is benign. In the National Lung Screening Trial (NLST), which enrolled about 53,000 heavy smokers in the U.S., over 96 percent of the positive LDCT screening results were actually false positives. These types of results require subsequent workup, for example through further CT or PET scans and biopsies. This causes additional costs and can be a substantial psychological burden for patients.
New criteria for interpreting screening results, however, might alleviate the problem. Since the NLST, U.S. organizations like the American College of Radiology (ACR) have explained in great detail how to determine if a nodule should be considered positive and thus in need of further investigation.1 “Previously, a nodule had to be 4 mm in diameter, but other studies suggest we can safely raise the threshold size without compromising the sensitivity of LDCT screening,” explains Denise Aberle of UCLA Medical Center in Los Angeles, who was one of the principle investigators on the NLST. A higher nodule threshold size would likely decrease false positives and might result in fewer downstream costs.
The National Lung Screening Trial – Key Facts
Breath Tests for Cancer
In addition, new screening tools such as genetic sequencing and breath tests for cancer metabolites are on the horizon and could further improve screening accuracy in individual patients. For example, advances in sensor technologies and breath collection methods are paving the way for breath tests that could separate patients with lung cancer from those without. The metabolism of people with lung cancer is different to that of healthy people and this is reflected in the chemical signature of their breath. Thus, the tests could become one of the first steps taken to identify patients at risk.2 Several breath-test prototypes are being developed by companies around the world.
Another future method for detecting lung cancer might be blood tests for genetic sequencing. While much remains to be elucidated within the area of genomic profiling and disease, researchers have recently identified the most common genetic mutations associated with lung cancer subtypes.3 CT scans could be used to verify positive results from such tests in individual patients. Conversely, these tests could be used to reduce false positive rates from screening CT scans. Other diagnostic tools, such as detecting lung cancer using biomarkers circulating in the blood, are at earlier stages of research and development.4
New Surgical Techniques
Meanwhile, treatment possibilities are also improving. Positive results from immunotherapy clinical trials were reported earlier this year.5 As the field of personalized medicine expands, it may be possible to better match patients to targeted therapies designed for subgroups of cancer. Surgical techniques are developing, too. For example, there are ongoing endeavors to establish improved image-guided minimally invasive procedures for removing cancerous tissue through small chest incisions in the early stages of lung cancer.6 Such innovative approaches may be what is needed to increase patients’ survival and improve their quality of life.
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