Thoracic Oncology Program
Lung Cancer Screening Guide
Lung cancer is the No. 1 cancer killer in the United States, with 160,340 people expected to die from it this year. In part, this is because there has been no reliable way to detect lung cancer in its earliest, most treatable stage. Now, new guidelines suggest that lung cancer screening for people at very high risk can help reduce the number of deaths from this disease.
Who should be screened for lung cancer?Recent research has shown that people aged 55-75 who currently smoke, or have smoked at least 30 pack years (1 pack of cigarettes a day for 30 years) can reduce their chances of dying from lung cancer by undergoing a process of screening. As with many cancers, the earlier it is detected, the better the chance for success.
Where do these screening guidelines come from?The National Lung Screening Trial provided the first evidence that lung screening can reduce cancer deaths, when data from the study was published in 2011.
The National Lung Screening Trial began in 2002 and enrolled more than 53,000 participants who were current or former heavy smokers, ages 55 to 74. The trial randomly assigned people to receive lung screening either by low-dose helical CT scans or chest X-rays. The trial was sponsored by the National Cancer Institute, and the University of Michigan was one of 33 places across the country to take part. U-M enrolled 850 participants.
What were the results of the trial?The trial found 20% fewer lung cancer deaths among those participants screened with low-dose helical CT compared to those screened with chest X-ray. A secondary finding, which was not the main goal of the trial, showed that deaths from all causes, including lung cancer, were 7% lower in the CT-screened group. The study looked specifically at people at high risk for lung cancer based on smoking history and age. The results should not be generalized to everybody.
What is a helical CT scan?Low-dose helical CT, also called spiral CT, uses X-rays to scan the entire chest in about 5 to 10 seconds during a single breath-hold. The CT scanner looks like a donut, with the person undergoing a CT scan lying still on a table that moves through the opening in the scanner as the CT machinery rotates around the person. A computer creates images from the X-ray information coming from the scanner and then assembles these images into a series of two-dimensional slices of the lung at very small intervals to provide excellent detail and enable the detection of very small lesions, referred to as nodules, that are often smaller than 1 centimeter.
What are the risks of lung screening?Risks include:
- False-positive results:
In other words, something shows up on the test, but turns out not to be cancer.
- Physical harm from additional testing or surgery to evaluate the abnormal findings.
For example, lung biopsies can lead to partial collapse of the lung, bleeding, infection, pain and discomfort.
- Exposure to radiation:
The helical CT scans used for lung cancer screening use a very small amount of radiation, less than used for most CT scans. The annual exposure from screening adds up over years. The cumulative effect of radiation exposure is not known, but for those at high risk for lung cancer, the risk from the low level of radiation exposure from screening is not felt to be a significant.
Why can't everyone be screened?There are risks associated with lung screening. Up to half of patients undergoing a screening lung CT scan may have a lung nodule found. When a nodule is found, patients must undergo additional testing to determine if it is cancerous or benign. These additional tests can include more imaging with radiation exposure or even surgery to remove the nodule. The vast majority of nodules that are identified -- more than 98% to 99% -- turn out not to be cancer. This means people may needlessly face physical harm or discomfort, worry and expense.
Lung screening is expensive. Screening everyone for lung cancer would add a tremendous burden to the health care system, including federal and state governments who fund Medicare and Medicaid programs.
At this time, there is no evidence to support screening people who have not been heavy smokers or those who have been exposed to second- hand smoke. Scientists are trying to find biomarkers or other indicators to help determine who is most at risk of developing lung cancer. In the meantime, the best evidence we have limits possible screening recommendations to older adults who have been heavy smokers.
How can I get a lung cancer screening?The University of Michigan Comprehensive Cancer Center offers a Lung Cancer Screening Clinic for people at high risk.
What else can I do if I'm concerned about lung cancer?Talk to your doctor about your lung cancer risk and what you can do to reduce it. The single biggest thing anyone can do to prevent lung cancer is to stop smoking or don't start. For help quitting, visit U-M's Tobacco Consultation Service or call 734-998-6222.