Lung cancer remains the most common cause of cancer related death in the United States. This is despite the decline in cigarette smoking over the last 50 years
In patients at increased risk, a screening with an annual low radiation dose CT of the chest may decrease the number of deaths. Many professional organizations recommend this test. It is also endorsed by the US Preventive Services Task Force and the Centers for Medicare & Medicaid Services.
Lung Cancer: False positive results are common with screening
A “positive” result indicates an abnormality in the lungs that could be cancer. Most often, this abnormality would be a very small nodule (“spot”) within the lung. These nodules are too small (typically under one centimeter) to directly cause symptoms. Often, people are surprised to hear that a nodule is present. Small non-cancerous nodules are very common, particularly in people who have a history of cigarette smoking. In fact, in the largest study to date, nearly 40 percent of high risk patients had a positive screening test on at least one of three CT scans. Of these positive studies, only 4 percent see a diagnosis of lung cancer.
Some nodules have more concerning features
Every case is unique; reviewing the case with a health care provider familiar with lung cancer screening is important. In general, the most important features of nodules that suggest cancer are size and growth. Lung nodules under 4-6mm (about ¼ inch) are unlikely to be cancer and may not require any additional testing outside of the annual CT scan. “Calcified” nodules are typically non-cancerous and may not require further testing. “Non-calcified” nodules greater than 6mm or those showing growth between scans generally require more evaluation.
When we recommend more testing
We may pursue further testing depending on the appearance, size, and growth pattern of the nodule. In many circumstances, the nodule will be followed over time with low-radiation dose CT scans at 3-6 month intervals. If there is no growth for 2 years (longer for some types of nodule), the nodule is unlikely to be cancer. If the nodule has more concerning features, we may do a scan called a PET/CT. Alternatively, we may recommend a surgical or non-surgical biopsy.
Lung cancer screening at the University of Vermont Medical Center
If you smoke now or have in the past, ask your healthcare provider if screening is appropriate for you. We perform screening tests at the University of Vermont Medical Center. A dedicated Lung Nodule Clinic and the Lung Cancer Multidisciplinary Clinic are available for people with a positive result on a CT screening.
Garth Garrison, MD, is a pulmonary disease physician at The University of Vermont Medical Center and an assistant professor at the Larner College of Medicine at UVM.