Low-Dose CT Screening for Early Lung Cancer Detection

Lung cancer is the single deadliest form of cancer worldwide and accounts for approximately 20% of cancer deaths in the U.S. Lung cancer deaths climbed steadily from 1930 through 1990, when 91.1 out of every 100,000 men died of lung cancer. Death rates for women continued to rise until 2002, when they peaked at 41.6 per 100,000. Fortunately, lung cancer death has been falling since that time for both males and females due to both a decline in smoking and advances in detection and treatment. In 2019, just 40.1 men and 28.2 women in 100,000 died of the illness.

A Race Against Time

A primary reason lung cancer is so deadly is that it often causes no symptoms until it has spread to other parts of the body. By that time, treatment options are more limited, and chances of long-term survival are much slimmer. In early stages, it’s often possible to remove lung tumors in surgery. In some cases, this can eradicate the cancer cells with no further treatment needed. In others, additional treatments like radiation and/or chemotherapy may be necessary to eliminate cells that remain after surgery. After lung cancer has spread, it can no longer be eradicated with surgery, and doctors must rely on drug and radiation therapy to attack cancer cells.

The two main types of lung cancer are small cell and non-small cell cancers. Small cell cancer is much more aggressive and harder to detect, even with the latest screening technology, pushing survival rates lower for this type of illness. Fortunately, small cell cancers account for only 10–15% of lung cancer cases. Survival rate data illustrates the immense value of detecting lung cancer as early as possible. The 5-year survival rate reflects the percentage of patients in each category who are living five years following diagnosis.

The following data represents patients diagnosed between 2012 and 2018. Keep in mind that if current trends continue, patients diagnosed in later years may experience better survival rates.

The Search for Earlier Clues

Early attempts to screen for cancer relied on standard chest X-rays. However, while this type of screening found early-stage cancers, trials showed no improvement in mortality. Because CT scans provide better visibility than chest X-rays, researchers began investigating CT as a lung cancer screening tool.

In 2002, the National Institutes of Health sponsored the National Lung Cancer Screening Trial(NLST). The study followed more than 53,000 current and former heavy smokers who received annual screenings for three years via either low-dose CT (LDCT) or chest X-ray. The researchers found that within an average of 6.5 years, participants who were screened with LDCT experienced 15 percent to 20 percent fewer lung cancer deaths—3 fewer per 1,000—than those screened with chest X-ray. Following the publication of these encouraging results, physicians and professional organizations including the American Cancer Society, American Lung Association, and others began recommending LDCT screening for patients at high risk of developing lung cancer.

Current Lung Cancer Screening Recommendations

The US Preventive Services Task Force (USPSTF), which guides which procedures must be covered by most insurers, and other medical associations recommends annual LDCT lung cancer screening for patients who meet all the following criteria:

• Current smoker or former smoker who quit within the past 15 years

• Between 50 and 80 years old

• At least a 20 pack-year smoking history

A pack-year is the equivalent of a pack of cigarettes a day for one year. For example, a person who smoked a pack a day for 20 years, one who smoked two packs a day for 10 years, and one who smoked ½ pack a day for 40 years all have 20 pack-year histories.

Because these are not the only patients who are at high risk for lung cancer, it’s important for individuals to consult with their doctors about their lung cancer concerns and determine if LDCT screening would be beneficial. If you have COPD or have been exposed to lung carcinogens like radon or asbestos, ask your doctor about their recommendation for screening.

Benefits vs. Risks of LDCT Lung Screening

The NLST demonstrated that LDCT screening can reduce death from lung cancer and result in fewer deaths from all causes than X-ray screening. However, screening is not without risks of its own. Many potentially concerning features found on a lung CT are not cancer. As a result, screening patients may be subjected to unnecessary medical interventions as a result of screening. In some cases, patients develop serious complications as a result of invasive procedures. For this reason, LDCT lung screening is recommended only for those facing a high risk of lung cancer. Those who do choose this procedure should select a provider with specialized expertise in lung cancer screening and treatment.

What to Expect

LDCT lung screening is quick and painless. “Low dose” means that the exam uses a smaller amount of radiation than other CT tests. The test doesn’t require contrast dye, and patients can eat and drink normally in the hours leading up to the procedure. The patient lies on their back on the exam table, and the scan takes just about 10 minutes of a 30-minute appointment. When LDCT is performed at Iowa Radiology, we send a report to the referring provider within one business day.

At Iowa Radiology, we strive to provide patients with the information they need to make the best choices for their health. The best way to protect yourself against lung cancer is to quit smoking or never start. If you need help quitting, talk to your doctor. Many resources are available to help smokers who are struggling to quit. To stay up to date on our latest health care articles, subscribe to our blog.

Resources

American Cancer Society. Key Statistics for Lung Cancer. Cancer.org. Published January 12, 2023. Accessed July 14, 2023. https://www.cancer.org/cancer/types/lung-cancer/about/key-statistics.html. 

American Cancer Society. Lung Cancer Survival Rates. Cancer.org. Revised March 1, 2023. Accessed July 14, 2023. https://www.cancer.org/cancer/types/lung-cancer/detection-diagnosis-staging/survival-rates.html.

Ellis ME. Living with Non-Small Cell Lung Cancer: What’s My Prognosis? Healthline.com. Published March 4, 2021. Accessed July 14, 2023. https://www.healthline.com/health/lung-cancer/non-small-cell-lung-cancer-prognosis.

Mayo Clinic. Lung Cancer Screening. Published February 11, 2022. Accessed July 14, 2023. https://www.mayoclinic.org/tests-procedures/lung-cancer-screening/about/pac-20385024.

National Cancer Institute. National Lung Screening Trial: Questions and Answers. Cancer.gov. Updated November 12, 2014. Accessed July 14, 2023. https://www.cancer.gov/types/lung/research/nlst-qa.

National Cancer Institute. Patient and Physician Guide: National Lung Screening Trial (NLST). Cancer.gov. Accessed July 14, 2023. https://www.cancer.gov/types/lung/research/nlststudyguidepatientsphysicians.pdf

Radiological Society of North America. Lung Cancer Screening. Radiologyinfo.org. Reviewed November 1, 2022. Accessed July 15, 2023. https://www.radiologyinfo.org/en/info/screening-lung.

Taylor AP. The 10 deadliest cancers, and why there's no cure. LiveScience.com. Published September 21, 2022. Accessed July 14, 2023. https://www.livescience.com/11041-10-deadliest-cancers-cure.html.

Thomas A, Pattanayak P, Szabo E, et al. Characteristics and outcomes of small cell lung cancer detected by CT screening. Chest. 2018 Dec;154(6):1284–1290.https://dx.doi.org/10.1016/j.chest.2018.07.029.