CT Lung Cancer Screen Q&A

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What Is A CT Lung Cancer Screen, And How Is It Performed?
A CT lung cancer screen is a low-dose scan that can detect lung cancer in its earliest stages, when it is easiest to treat. CT lung cancer screens are easy. The entire exam takes less than 15 minutes. No medications, needles, food restrictions or patient gowns are required. You must however, be able to hold your breath for about 10 seconds. Patients simply lie down, place their hands over their head and are slipped in and out of the CT tunnel. The actual scan takes less than 10 seconds.

What Are The Risks?
Radiation exposure — Each day, we are exposed to background or natural occurring radiation. Depending on where a person lives in the United States, the average annual natural dose of radiation is around 3.0 mSv. For the average-size patient, the estimated radiation dose of a low-dose CT lung cancer screen is around 1.5 mSv. For patients who are high risk for developing lung cancer, the benefits of having a CT lung cancer screen far outweigh the risks associated with the small amount of radiation exposure.

False negatives — Low dose CT cannot detect all lung cancers. It is possible to have a lung cancer that is not detected during the CT screen.

False positives — CT scans are very sensitive. They can identify pulmonary nodules that may look suspicious but are actually benign, or noncancerous. There is a 25 percent chance that a nodule will be detected during a CT screen on a high-risk patient, but less than 2 percent of those detections are lung cancer. Depending on the size and appearance of the nodule, follow up CTs may be recommended to monitor changes in nodule size, or an invasive procedure, such as a needle biopsy, bronchoscopy or surgery, may be recommended to determine if the nodule is actually cancerous.

What Are The Possible Results Of My CT Lung Cancer Screening?
The purpose of performing a CT lung cancer screen is to identify pulmonary (lung) nodules. Lung nodules may develop for many reasons, such as inflammation, infection, scar tissue, abnormal tissue formation, blood vessel abnormalities, primary lung cancer or cancer from other areas of the body.

Lung nodules are quite common and are found on one in 500 chest X-rays and on one in 100 CT chest scans. Approximately 150,000 lung nodules are detected in the United States each year. Nodules will be found on approximately 50 percent of CT chest scans of smokers over the age of 50, but the vast majority
of these lung nodules are noncancerous.

Negative Finding — If no identifiable nodules are found or if a nodule is found that is <4 mm, the exam is considered negative. The National Comprehensive Cancer Network recommends the CT lung cancer screen be repeated every 12 months for at least two years on patients with negative findings. These patients are eligible for the discounted CT lung cancer screen rate the following year.

Positive Finding — If the scan identifies a nodule, the NCCN recommends the following:
  • 6–8 mm, a repeat CT scan in three months to see if the nodule has grown.
  • >8 mm, a PET/CT scan, bronchoscopy, needle biopsy or surgical excision, based on the nodule’s appearance on the CT scan images.

Lutheran’s nurse navigator will inform you and your referring physician of a positive finding and remind you of the NCCN’s follow-up recommendations. The nurse navigator will also coordinate your follow-up appointments.

Note: All follow-up CT exams for lung nodule tracking are billed to insurance because they are no longer considered screens.

Incidental Finding — A CT of the lungs covers from the top of the chest to just below the diaphragm. Beside the lungs, there are other organs, soft tissue and bone structures that will be imaged. An incidental finding is the discovery of a pathology or disease process other than a pulmonary nodule. Some common incidental findings include an enlarged heart, hiatal hernia or pneumonia. Incidental findings may require a follow-up appointment with your physician.

Sources: lahey.org, mayoclinic.com, mskcc.org, ucsfhealth.org