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 77 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 do not have symptoms of lung cancer
  • Patients who are fit enough to undergo curative surgery or radiation if lung cancer is discovered at screening

These criteria are recommended by the US Preventive Services Task Force and were amended by the Center for Medicare and Medicaid Services (CMS). They are 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. It can be ordered following documentation of a counseling and shared decision-making visit.

A lung cancer screening counseling and shared decision-making visit includes the following elements (and is appropriately documented in the beneficiary’s medical records):

  • Determination of beneficiary eligibility including age, absence of signs or symptoms of lung cancer, a specific calculation of cigarette smoking pack-years and the number of years since quitting if a former smoker
  • Shared decision making, including the use of one or more decision aids, to include benefits and harms of screening (follow-up diagnostic testing, over-diagnosis, false positive rate and total radiation exposure)
  • Counseling on the importance of adherence to annual lung cancer LDCT screening, impact of co-morbidities and ability or willingness to undergo diagnosis and treatment
  • Counseling on the importance of maintaining cigarette-smoking abstinence if a former smoker or the importance of smoking cessation if a current smoker and, if appropriate, furnishing of information about tobacco cessation interventions
  • If appropriate, the furnishing of a written order for lung cancer screening with LDCT

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 that is run by a multidisciplinary team of health professionals specially trained to conduct a smoking cessation consult:

Mass General Tobacco Treatment Service

Out-patients can be referred to:

Massachusetts Smokers' Helpline (free and confidential)
800-QUIT-NOW (800-784-8669)

What is a positive finding?

A positive finding is the presence of an abnormality, most commonly a solid nodule that is 6 mm or larger or a ground-glass nodule larger than 20 mm. Positive scans are categorized (0-4) according to the size or growth of a nodule (Lung RADS). A higher category signifies a more suspicious nodule, corresponding to a greater risk of malignancy.

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 recommended, 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. Therefore, it is important to counsel patients on the importance of continuing with annual screening with LDCT.

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

The risks of low-dose CT scans (LDCT) can be divided into false positive or negative findings, over-diagnosis, incidental findings, radiation exposure and anxiety.

False Positive Findings: While LDCT screening for lung cancer can save lives, it has a high number of false positives, findings that appear abnormal but turn out to be non-cancerous. An example is a nodule caused by a scar or old infection. Up to one quarter of patients screened will have a finding in the lungs that requires further testing, but the majority of these findings do not represent cancer. Further tests are most commonly a repeat CT scan but may include referral to specialists at a multidisciplinary nodule clinic, a PET scan, a lung biopsy or surgery.

False Negative Findings: Screening may not pick up some cases of lung cancer. In the National Lung Screening Trial (NLST), about 4% of lung cancers were not detected at screening.

Over-diagnosis: Screening can discover small lung cancers that may not cause any harm in a patient’s lifetime but can result in further testing or surgery.

Incidental Findings: Other findings may be discovered in organs that are also imaged during LDCT, such as the heart, abdomen, blood vessels and thyroid gland. You may already be aware of some, and some might be new findings. These findings may require further testing.

Radiation exposure: 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.

Anxiety: Having an LDCT, waiting for the results and further evaluation for positive or incidental findings may cause stress and anxiety in some patients.

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)

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 a low-dose CT scan (LDCT) be reported?

The LDCT is reported by one of a team of dedicated thoracic radiologists who have many years of expertise in reporting chest CT and evaluating lung nodules. The radiologist will report the scans in accordance with a nationally accepted reporting algorithm, LUNG-RADS, and a system for management of positive results, including clear protocols for invasive procedures. The algorithm for reporting results is similar to BI-RADS. The report will be received in the same fashion as other CT scan reports. 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.






Lung Screening at Mass General

Learn about eligibility for lung cancer screening at Mass General.


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