Definition & Overview
Lung cancer screening is a medical procedure performed to diagnose the presence of lung cancer in patients who are considered at a higher risk of acquiring the disease and who are showing key symptoms. It is also performed in the hopes to catch the disease in its early stages to raise the chances of successful treatment. Although this testing process is not proven to reduce mortality due to the difficulty faced in detecting certain types of lung cancer, the screening is still used widely due to the lack of other alternatives.
Lung cancer screening aims to find malignant cells in the tissues of the lungs. With lung cancer leading the race as the most fatal cancer type due to the heightened risk of smokers and previous smokers, this screening is widely requested.
Who Should Undergo and Expected Results
A lung screening test is typically prescribed by physicians to:
- Those aged 55 to 74 years
- Those who smoke
- Former smokers who have quit smoking within the last 15 years
- Have a smoking history that involves at least 30 packs per year
- Those who are exposed to secondhand smoke for a prolonged period
The tests are also prescribed for those who experience symptoms that are often linked to lung cancer. These include:
- Chronic raspy coughing
- Blood-streaked mucus
- Hacking coughs
- Recurrent pneumonia
- Recurrent bronchitis
- Shortness of breath
- Wheezing coughs
- Persistent pain in the chest
- Swollen neck
- Swollen face
- Pain in arm, hand, or shoulder
- Loss of appetite
- Unexplained weight loss
- Severe headaches
- Body aches and pain
- Difficulty swallowing food properly
- Intermittent fever
- Abnormal sounds coming from the lungs
- Swollen lymph nodes near the collarbone
A person needs to be in fairly good health to be a candidate for this type of screening because there are risks to the procedure, and the risk may not be worth taking for some people who have existing medical problems. Patients who have illnesses or who are not strong enough to have surgery may not benefit enough from such screenings.
Moreover, there are some factors that may hinder a person from undergoing a screening test for lung cancer. For example, people who have metal chest implants such as pacemakers or metal rods in the spine are not qualified for the screening as these metals can easily interfere with the X-rays that are used in the process. This results in images that are of low quality and would not be able to be of much help to the diagnosing physician.
A lung screening provides crucial information that the diagnosing physician can use to determine whether the patient is suffering from lung cancer. If the condition is caught early or while on its early stages, the patient can immediately undergo appropriate treatment that will increase his chances of survival.
It should also be expected, however, that the screening process might not always produce accurate results. There were times when the screening failed to detect cancer that is already present and there were cases when the test came back with a false positive result. In some situations, the screening might also catch a disease in its progressive stages, which is why a lung cancer screening does not guarantee an absolute chance of survival. In other cases, the procedure may also produce findings that require additional information and further tests before any definite conclusion can be made; in such cases, a CT scan or a lung biopsy is often performed following the screening procedure.
Studies show that 1 out of every 4 lung cancer screening tests is likely to show abnormalities that may be cancer in the lungs or the surrounding areas. To make sure that the abnormality found is indeed cancer, more tests and scans are usually required.
How Does the Procedure Work?
There are different types of screening tests that are typically used, and each one detects cancer in a different manner. These include:
Low-dose spiral CT scan or LDCT - The low-dose spiral CT scan has been proven to be more effective in detecting cancer at an early stage, which leads to better chances of survival. This test, which captures detailed images of the lungs using low-dose radiation, uses an x-ray machine that follows a spiral path as it scans the body. The results are sent from the machine to a computer that processes the images.
Chest x-ray – A chest x-ray is another test used for lung cancer screening; it works by scanning the organs inside the chest as well as nearby bones using an X-ray technology, or more specifically, an energy beam that goes through the body then translates the image of the body’s interior on film.
Sputum cytology – This technology makes use of a sample of mucus or sputum that the person produces when he coughs. This sample is placed under microscopic analysis to look for cancerous cells.
Lung cancer tests are conducted at facilities that are equipped with the specific type of technology that the procedure requires, i.e. the correct type of scanner.
Possible Complications and Risks
Before undergoing a screening test for lung cancer, it is important to be aware of the advantages and disadvantages of the procedure. It is important to keep in mind that lung cancer screening has its possible complications and risks that may outweigh the benefits, such as:
- The risk of having a false-positive result, which may lead to tests and surgeries that are unnecessary and may thus expose the patient to greater risk
- The risk of overdiagnosis, which may lead to unnecessary treatment
- The risk of radiation exposure, especially in chest x-rays and low-dose spiral CT scans
Although these screening tests have been proven to be helpful in many ways, they are also not effective 100 percent of the time, and do not necessarily eliminate or reduce mortality.
Johnson DH, Blot WJ, Carbone DP, et al. Cancer of the lung: non-small cell lung cancer and small cell lung cancer. In: Abeloff MD, Armitage JO, Niederhuber JE, et al, eds. Abeloff's Clinical Oncology. 4th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2008:chap 76.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Non-small cell lung cancer. Version 4.2014. Available at: http://www.nccn.org/professionals/physician_gls/pdf/nscl.pdf. Accessed August 31, 2014.