Lung cancer screening and diagnosis at a glance
- Lung cancer screening seeks to identify lung cancer before symptoms appear, often while it is at an early stage and before it has spread.
- Lung cancers found early in screenings have proven likely to respond to treatments and more likely to reduce risk of death, although clinical trials have not validated these benefits for all types of screenings, and screenings also carry certain risks.
- Oncologists (cancer doctors) make a lung cancer diagnosis after discovering lung cancer, then they further diagnose its stage of development.
What is lung cancer screening & diagnosis?
Lung cancer screening attempts to identify cancer before symptoms occur. Oncologists make a lung cancer diagnosis when cancer has been identified in the lung(s). Describing the stage of the cancer is a part of diagnostics that pinpoint the particular type of lung cancer, its severity, and metastasis (spread).
Oncologists screen for lung cancer in order to catch it at an early stage when it has been shown to be more treatable and can help reduce the risk of death. They also study lung cancer screening tests to help identify traits that put people at greater risk of getting lung cancer, as well as to refine the screening tests to reduce risks.
According to the Centers for Disease Control and Prevention, the only recommended screening test for lung cancer is a low-dose CT scan (LDCT). In this test, a special X-ray machine scans the body, and a linked computer generates detailed images.
The U.S. Preventive Services Task Force recommends annual scanning for people who are heavy smokers (a pack of cigarettes a day for 20 years or the equivalent) or have been in the past 15 years and if they are age 50-80. Sputum cytology tests (lab analysis of mucus from the lung) may also be part of the screening.
In 2011, a study of 53,454 current and former smokers known as the National Lung Screening Trial found that participants who had LDCT screenings reduced their risk of death by 15 to 20 percent over participants who received standard chest X-rays.
However, there are multiple risks related to any kind of screening, including:
- Chest X-rays and LDCTs expose the chest to radiation
- False-negative result: test shows no cancer but there actually is
- False-positive result: test shows cancer but there isn’t any
- Finding cancer may not improve a patient’s health or longevity.
Patients should discuss these issues and other implications of screening with their physicians before undergoing any screening for lung cancer.
Preventive lung cancer screening program at cCARE
As oncologists, we unfortunately often see patients whose diagnosis of lung cancer occurred too late for it to be cured. To make a difference, cCARE believes that we need to increase our efforts to identify the disease early.
Learn about cCARE’s Lung Cancer Screening San Diego Program
Who should be screened?
- Ages 55-74 with current heavy tobacco use
- More than 30 packs per year within the past 15 years, current or recent use
- Age >50 with a 20 pack per year history of smoking with one of several additional risk factors for lung cancer such as family history, asbestos exposure, etc.
How to get screened
Individuals who wish to be screened can contact us directly or have their doctor refer them. Once patients are at the clinic they will be evaluated to see if they are candidates for screening and will be counseled on the screening process.
For referral providers
Lung cancer diagnosis & staging
In a screening procedure being conducted for an unrelated reason, the physician may detect abnormalities appearing on an MRI, CT scan or PET scan (see definitions below) and subsequently order a biopsy of the abnormal area. Or a doctor may follow up on symptoms of lung cancer such as intense and persistent coughing and order a biopsy.
In a biopsy, a healthcare professional passes a needle through the skin into the lungs to sample a small piece of the affected area. In other cases, a physician may perform a bronchoscopy, inserting a small tube with a tiny camera through the nose or mouth while the patient is under sedation to view and remove tissue. This biopsy sample is tested in the laboratory, which determines if there is cancer, what type of cancer it is and how far it has advanced.
Lung cancer staging
After a diagnosis of lung cancer, a patient may undergo staging tests to show the extent of the disease and whether it has metastasized. Staging tests include the following.
- In a CT (computer tomography) scan, a computerized X-ray machine makes a series of images of the torso, brain, limbs or other parts of the body.
- A PET (positron emission tomography) scan makes detailed, computerized pictures inside the body. The patient receives an injection of a small amount of radioactive glucose (sugar), and because cancer cells use more glucose than healthy cells, a concentration of glucose in any area suggests cancer cells.
- In an MRI (magnetic resonance imaging) scan a strong, computerized magnet takes pictures of the head and/or spine to determine whether cancer has spread to those areas.
- A bone scan uses a small amount of a radioactive substance injected into a blood vessel, with higher amounts of the substance collecting in cancerous areas in the bones.
Stages of non-small cell lung cancer
There are two types of lung cancer: non-small cell and small cell. About 85 percent of lung cancers are of the non-small-cell type. The stages of non-small cell lung cancer are as follows.
- Occult stage lung tumor. Cancer cells present in sputum from the lungs but imaging tests don’t indicate a tumor.
- Stage 0 lung tumor (carcinoma in situ). Cancer cells confined to the inner lining of the lung and not an invasive cancer.
- Stage I lung cancer. Invasive, having grown from the inner lining into other lung tissue but not yet into nearby tissue. The tumor is no larger than 5 cm (centimeters) across, about two inches, and there are no cancer cells in nearby lymph nodes.
- Stage II lung cancer. A 7 cm tumor and cancer is in nearby lymph nodes. Or the cancer may not be in nearby lymph nodes but the tumor is more than 5 cm or it has invaded nearby tissues. More than one tumor may exist in the same lobe of a lung.
- Stage III lung cancer. Involves multiple tumors of any size within the lung, and the tumor may have reached the heart or other nearby organs. Cancer cells may also inhabit lymph nodes on either side of the chest or neck.
- State IV lung cancer. One or more of three conditions exists: tumors are in both lungs, have spread to other parts of the body, or cancer cells exist in fluid between the two layers of the pleura, the tissues that protect the lungs.
Stages of small-cell lung cancer
Only about 15 percent of lung cancer cases are the small-cell type. While this kind of tumor grows more quickly than the large-cell variety, it also responds better to chemotherapy.
- Limited stage is when cancer exists on only one side of the chest.
- Extensive stage means cancer is in the lung and in tissues on the other side of the chest, or the cancer is found in distant organs such as the brain or in the fluid between the two layers of the pleura.