To help doctors give their patients the best possible care, the American College of Chest Physicians (ACCP) and the American Society of Clinical Oncology (ASCO) developed evidence-based recommendations on using computed tomography (CT) scans to screen for lung cancer in people who smoke or who have previously quit smoking. This guide for patients is based on the ACCP and ASCO recommendations.
- Lung cancer is more common in people who smoke, particularly those who smoke frequently or who have smoked for a long time.
- CT screening has been shown to lower the risk of death from lung cancer for heavy smokers, and the ACCP and ASCO recommend CT screening for certain people who smoke.
- Screening is not a replacement for quitting smoking. Quitting smoking is the only way to lower the risk of developing lung cancer.
Recently, results from the National Lung Screening Trial (NLST)  showed that there were 20% fewer lung cancer deaths in people who received screening with a low-dose CT scan than with a chest x-ray. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient's vein to provide better detail in the images.
Recommendations for Lung Cancer Screening
The ACCP and ASCO recommend the following lung cancer screening schedules for people who currently smoke or who have quit smoking:
- Yearly screening with a low-dose CT scan is recommended instead of screening with a chest x-ray or no screening for people age 55 to 74 who have smoked for 30 pack years or more or who have quit within the past 15 years.
- CT screening is not recommended for people who have smoked for less than 30 pack years, are younger than 55 or older than 74, have quit smoking more than 15 years ago, or have a serious condition that could affect cancer treatment or shorten a person's life.
If you currently smoke, screening for lung cancer is not a substitute for quitting smoking. Quitting smoking is the only way to reduce your risk of lung cancer.
However, CT scanning may help find lung cancer earlier when treatment is likely to work better. The NLST showed that three lung cancer deaths were prevented for every 1,000 people who received CT screening. The benefit of screening also appeared to outweigh the risks of the radiation from the low-dose CT scans . There is a risk that CT screening can find abnormal areas in the lungs that are not cancerous. If an abnormal area is found on CT screening, more testing would still be needed to find out if it is cancerous or noncancerous. CT screening also increases the likelihood of being diagnosed with and treated for lung cancer because screening may sometimes find slow-growing cancers that would not have been found otherwise.
If you are considering lung cancer screening, it's important that it is done at a cancer center  that can provide the complete support and resources needed for the screening, as well as evaluating the images, managing the results, and diagnosing and treating cancer.
Questions to Ask the Doctor
Consider asking the following questions of your doctor:
- What is my risk of lung cancer?
- Can you help me calculate my pack years for my smoking history?
- If I still smoke, how can you help me quit?
- What are the risks and benefits of screening for lung cancer with a CT scan?
- Do you recommend I receive a CT scan to screen for lung cancer?
- Where can I receive screening that can provide assistance and support throughout the process?
- What are the next steps if the CT scan indicates cancer?
Quitting Smoking 
Cancer Screening 
To help doctors give their patients the best possible care, ASCO and the organizations it partners with ask medical experts to develop evidence-based recommendations for specific areas of cancer care, called clinical practice guidelines. Due to the rapid flow of scientific information in oncology, new evidence may have emerged since the time a guideline or assessment was submitted for publication. As a result, guidelines and guideline summaries, like this one, may not reflect the most recent evidence. Because the treatment options for every patient are different, guidelines are voluntary and are not meant to replace your physician's independent judgment. The decisions you and your doctor make will be based on your individual circumstances. These recommendations may not apply in the context of clinical trials.
The information in this patient guide is not intended as medical or legal advice, or as a substitute for consultation with a physician or other licensed health care provider. Patients with health-related questions should call or see their physician or other health care provider promptly and should not disregard professional medical advice, or delay seeking it, because of information encountered in this guide. The mention of any product, service, or treatment in this guide should not be construed as an ASCO endorsement. ASCO is not responsible for any injury or damage to persons or property arising out of or related to any use of this patient guide, or to any errors or omissions.
The best cancer care starts with the best cancer information. Well-informed patients are their own best advocates, and invaluable partners for physicians. Cancer.Net (www.cancer.net ) brings the expertise and resources of ASCO, the voice of the world's cancer physicians, to people living with cancer and those who care for and care about them. ASCO is composed of nearly 35,000 members who are the leaders in advancing cancer care. All the information and content on Cancer.Net was developed and approved by the cancer doctors who are members of ASCO, making Cancer.Net an up-to-date and trusted resource for cancer information on the Internet. Visit Cancer.Net to find guides on more than 120 types of cancer and cancer-related syndromes, clinical trials information, coping resources, information on managing side effects, medical illustrations, cancer information in Spanish, videos, podcasts, the latest cancer news, and much more. For more information about ASCO's patient information resources, call toll free 888-651-3038.