Lung Screening FAQ for Physicians

Use these frequently asked questions (FAQ) to learn more about lung cancer screening and access resources to help support patients.

FAQ for Physicians


Who should be screened for lung cancer?

Mass General screens patients who meet the following criteria:

  • Individuals between the ages of 55 and 80 who are current or former smokers
  • History of at least 30 pack years of smoking
  • Former smokers who have quit within the past 15 years
  • Patients who are fit enough to undergo curative surgery or radiation if lung cancer is discovered at screening
  • Asymptomatic individuals

These criteria are recommended by the US Preventive Services Task Force based on the National Lung Cancer Screening Trial (NLST), which found 20% fewer lung cancer deaths among a similar patient population when screened annually for three years using low-dose CT scanning (LDCT) compared to a standard chest X-ray. One cancer death was prevented for every 320 patients screened.

What test should patients have?

Specialist radiologists interpret imaging exams

A low-dose CT scan (LDCT) is the only screening test for lung cancer recommended by the US Preventive Services Task Force. The LDCT is reported by one of a team of dedicated thoracic radiologists who have expertise in this area, using an established reporting algorithm and a system for management of positive results, including clear protocols for invasive procedures.

Patients should also be referred for smoking cessation treatment because stopping smoking has been shown to be more effective than any other test or intervention in reducing the risk of lung cancer. All current smokers should be referred to smoking cessation counseling and medication consideration. Mass General has a program for in-patients only: the Tobacco Treatment Service (TTS) is a multidisciplinary team of health professionals specially trained to conduct a smoking cessation consult.

For outpatients, referral to the state’s free smoking cessation telephone counseling program can be made.

What is a positive finding?

A positive finding is the presence of an abnormality, most commonly a nodule that is 4 mm or larger. In the National Lung Cancer Screening Trial (NLST), 24% of low-dose CT scans (LDCT) had a nodule larger than 4 mm over the course of three scans. Over 96% of these positive scans did not show lung cancer. These nodules were likely to represent non-calcified granulomas or intra-parenchymal lymph nodes. Given these high rates of false positives, another study conducted by the ELCAP examined the effects of increasing the definition of a positive finding to a nodule 6 mm or larger. This reduced the number of patients needing follow-up by half and did not miss any lung cancers. Recently published guidelines by the American College of Radiology on management of screen-detected nodules (Lung RADS) have chosen to use 6 mm as the threshold for a positive finding.

LDCT may also detect incidental abnormalities such as cardiovascular disease, abdominal abnormalities or thyroid nodules, which may require follow-up. In NLST, 7.5% of participants had a significant finding other than lung cancer. Incidental findings may generate a recommendation by the reporting radiologist for further tests. As experience grows, the recommendations may change over time.

What options are available for patients with a positive finding?

CT lung cancer screening

A small nodule discovered by CT in the left lung (A)
enlarged on follow-up CT scan (B) and was found to
be an adenocarcinoma at surgery.

Patients with a positive screening low-dose CT scan (LDCT) will need further evaluation, most commonly CT scans at shorter intervals than the one-year screening interval to assess nodule growth. This recommendation will be clearly reported by the radiologist according to national guidelines. Approximately 6% will need more extensive evaluation that may include referral to, or consultation with, specialists at a multidisciplinary nodule-screening clinic comprised of thoracic radiologists, oncologists, surgeons and pulmonologists. Invasive procedures including biopsy, bronchoscopy or surgery may be needed, and these can be associated with complications. Referrals to the Mass General Lung Screening and Pulmonary Nodule Clinic can be made by emailing or via CRMS (for clinicians within Partners).

What is the incidence of lung cancer after a negative study?

In the National Lung Cancer Screening Trial (NLST), 4% of the lung cancers occurred after a negative scan and before the next scheduled annual screening. Some cancers occurred in those who missed screening.

What are the risks of low-dose CT scans (LDCT)?

LDCT exposes patients to a small amount of radiation comparable to a quarter of the dose of a standard chest CT and similar to the dose of a mammogram. It is equivalent to about a quarter of the dose received per year from background radiation at sea level.

How do I order a low-dose CT scan (LDCT)?

You can order LDCT through ROE (for clinicians within Partners) or ROE Portal (for clinicians outside of Partners) or by calling 617-724-XRAY (9729). Currently, LDCTs are performed at Mass General Imaging in Waltham and Chelsea.

What do I do if the patient has had a previous chest CT?

Prior CT studies are extremely helpful and can reduce the need for follow-up imaging. If the patient’s previous scan was performed at Mass General, it will be available for comparison for the reporting radiologist. If it was done at an outside institution, it will need to be loaded onto our PACS system through lifeIMAGE. If done prior to the patient having a low-dose CT scan (LDCT), a delay in reporting the scan can be prevented. If you need help loading studies, please contact our Imaging Service Center at 617-726-1798.

How will results be standardized?

Our radiologists have many years of expertise in reporting chest CT and evaluating lung nodules. They will report the scans in accordance with national guidelines and follow the Lung RADS Lexicon due to be published in summer 2014. This algorithm for reporting results is similar to BI-RADS. If you have any questions regarding the report, please e-mail the reporting radiologist.

How do I deal with incidental findings?

Incidental findings in the cardiovascular system, lungs and other organs may be significant. A recommendation will be made in the report on further evaluation of incidental findings. These recommendations may change over time as experience with low-dose CT scans (LDCT) increases. As always, please feel free to contact the reporting radiologist if you have any questions.






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Learn about eligibility for lung cancer screening at Mass General.


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