Low Radiation Scans Help Identify Cancer in Earliest Stages

A study of US veterans at high risk for developing lung cancer demonstrated that low-dose computed tomography (LDCT) imaging can be very successful in helping clinicians detect very small lung nodules that, in a small number of patients, may indicate the earliest stages of the disease. LDCT utilizes less than one-fourth of the radiation of a traditional CT scan.

The study’s findings were presented May 2013 at the American Thoracic Society (ATS) 2013 International Conference, held May 17-22, 2013, in Philadelphia, PA, USA. “Lung cancer is the leading cause of cancer-related death and has a poor survival rate,” said Sue Yoon, a nurse practitioner at Veterans’ Affairs (VA) Boston HealthCare West Roxbury Division (MA, USA). “Most of our veterans in these ages have a heavy smoking history and early screening is desirable to improve outcomes. Our study was undertaken to learn how often we would discover significant abnormalities and how to adapt our existing processes and interdisciplinary approaches to accommodate additional patients.”

Conducted according to guidelines established by the US National Comprehensive Cancer Network (NCCN), the study was based in part on the findings of the National Lung Cancer Screening Trial (NLST), which found that LDCT imaging resulted in a 20% decrease of lung cancer mortality compared to chest X-ray among heavy smokers aged 55 to 74 years.

The study enrolled 56 patients with a median age of 61 to 65 years and who had a smoking history of more than 30 pack years or 20 pack years and one additional cancer risk factor, such as occupational exposure to carcinogens or personal or family history of cancer or COPD. After reviewing LDCT scans of each patient, the researchers found that 31 patients had a nodule of 4 mm or larger or another abnormal opacity, six of which were deemed suspicious for malignancy. The study also found that 34 patients had more than one nodule. Four patients were diagnosed with biopsy-validated lung cancer.

“Our preliminary rate of lung cancer diagnosis after the first round of screening was 7%, which was significantly higher than NLST group, which had a preliminary rate of 3.8% at its first round,” Ms. Yoon said. “In addition, detection of nodules larger than 4 mm was 55% in our group compared to 27% in the NLST group.”

The difference in nodule prevalence rates between the current study and the NLST are in all probability due to three basic factors, Ms. Yoon noted. First, the current study had much smaller numbers than the multicenter NLST; second, the scanning technology used during the current trial had advanced since the earlier NLST trial was conducted; and finally, the populations evaluated in the NLST and the current study had considerable differences—for instance, the VA population was mostly male and most patients had COPD.

Even though the findings of both this study and the NLST suggest routine screening with LDCT technology can help identify patients in the early stages of cancer, establishing and supporting a regular screening program requires substantial resources and may not be feasible in all locations or for all populations, Ms. Yoon added. Furthermore, because the LDCT is highly sensitive, most of the nodules it spots are benign, and are often due to inflammation or scarring.

“Our previous experience with diagnosing and managing a high volume of incidentally discovered pulmonary nodules suggested that a low dose CT scan screening program, in which patients are screened annually, could be a substantial undertaking,” Ms. Yoon said. “Considerable effort goes into each step of the process: selecting patients, tracking abnormalities, further selecting patients with suspicious abnormalities for additional diagnostic and therapeutic interventions. “Although we plan to continue and expand the LDCT screening program, this will require additional planning and, potentially, resources,” she added. “Currently we are using a gatekeeper approach, to ensure tracking of nodules and other abnormalities that are discovered during screening LDCT.”


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VA Boston HealthCare West Roxbury Division