CT Scans in Lung Cancer Screening

New recommendations from the National Comprehensive Cancer Network (NCCN) say that patients determined to be at high risk for lung cancer should have regular screening with low-dose CT scans.

The NCCN guidelines define high-risk patients as:

• Age 55-74 plus ≥30 pack-year smoking history plus smoking cessation <15 years or
• Age ≥50 and ≥20 pack-year history of smoking and other risk factors besides second-hand smoke

A negative scan should be followed by annual low-dose CT scans for three years and then periodically until age 74.  If the baseline image reveals one lung nodule, the patient should have close follow up with additional low-dose CT scans, with the scan interval determined by the nodule’s characteristics.

According to the guidelines, a solid or partly solid nodule ≤4 mm requires annual screening with low-dose CT for three years and until age 74. Larger nodules have shorter screening intervals, ranging to follow-up CT in one month for patients with solid endobronchial nodules. Patients who have nodules with a ground-glass appearance require follow-up CT at intervals ranging from three to six months to 12 months, depending on nodule size.

Patients with a low or moderate risk for lung cancer do not need routine lung cancer screening.  The NCCN defines moderate-risk patients as age ≥50, a smoking history of ≥20 pack-years, and no additional risk factors. A low-risk patients is younger than 50 and has less than a 20 pack-year smoking history.

“Lung cancer screening with CT should be part of a program of care and should not be performed in isolation as a free-standing test,” according to the guidelines available on the NCCN website.

“Given the high percentage of false-positive results and the downstream management that ensues for many patients, the risks and benefits of lung cancer screening should be discussed with the individual before doing a screening low-dose CT.

“It is recommended that institutions performing lung cancer screening use a multidisciplinary approach that may include specialties such as radiology, pulmonary medicine, internal medicine, thoracic oncology, and thoracic surgery. Management of downstream testing and follow up of small nodules are imperative and may require establishment of administrative processes to ensure the adequacy of follow up.”

The NCCN offers additional guidance for solid and ground-glass nodules, based on specific nodule characteristics.

NCCN is a consortium of major US cancer centers.