Lung cancer is the most common cause of cancer death in Ontario. Screening for lung cancer using low-dose computed tomography (LDCT) has been the subject of many research studies since the 1990s. The National Lung Screening Trial compared LDCT with chest radiograph in high-risk populations and found a 20 percent reduction in lung cancer mortality at 6 years with LDCT after an initial scan and two annual rounds of screening. While there are still gaps regarding the use of CT-screening, researchers in Ontario developed evidence-based recommendations for screening high-risk populations for lung cancer.
Their guideline recommendations are published in the October issue of the International Association for the Study of Lung Cancer's journal, the Journal of Thoracic Oncology (JTO).
The key recommendations are:
- Screening for lung cancer with low-dose CT is recommended in high-risk populations defined as persons who are 55 to 74 years of age with a minimum smoking history of 30 pack-years or more
- Screening for lung cancer should be done using a low-dose CT multidetector scanner with the following parameters: 120 to 140 kVp, 20 to 60 mAs, with an average effective dose of 1.5 mSv or less
- A nodule size of 5 mm or more found on the low-dose CT indicates a positive result and warrants a 3-month follow-up CT. Nodules of 15 mm or more should undergo immediate further diagnostic procedures to rule out definitive malignancy.
- Follow-up CT of a nodule should be done at 3 months as a limited LDCT scan
- Persons at high risk for lung cancer should commence screening with an initial low-dose CT scan followed by annual screens for 2 consecutive years, and then once every 2 years after each negative scan.