Introduction

Lung cancer is the leading cause of cancer death globally, posing a serious public health concern. According to the GLOBOCAN 2022 statistics, lung cancer is the leading cause of cancer deaths worldwide, with an estimated 2.4 million cases and 1.8 million deaths. In the United States, the American Cancer Society estimates that about 226,650 new cases and 124,730 deaths will occur in 2025. There is a 1 in 17 chance and a 1 in 18 chance for a man and a woman, respectively, to develop lung cancer in their lifetime. This growing burden of lung cancer necessitates a focus on screening and prevention strategies.

There are two types of lung cancers: Non-Small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC). NSCLC represents over 85% of diagnosed lung cancer cases and has three main subtypes, namely adenocarcinoma (most common), squamous cell carcinoma, and large cell carcinoma. NSCLC tumors tend to be slightly larger and may have several actionable mutations. On the other hand, SCLCs can be smaller, more aggressive, and rarely have any targetable mutations.

Early detection can increase the survival rate by 20 to 33%, depending on which population you are examining. Hence, it is important to stay updated and create more awareness about the screening approach to improve survival rates and patient outcomes. In this article, we will discuss an overview of lung cancer screening, updated screening guidelines, and their interplay with cancer disparities.  

The 2023 Updated Guidelines for Lung Cancer Screening

The American Cancer Society (ACS) recommends annual lung cancer screening with low-dose CT scans (LDCT) for adults aged 50–80 who:

• Currently smoke or used to smoke, AND
• Have a 20+ pack-year smoking history (e.g., 1 pack/day for 20 years).

Key Changes:

• No longer requires a "years since quitting" (YSQ) rule for former smokers.

Who Should NOT Be Screened?

• People with serious health conditions that shorten life expectancy.
• Those unwilling or unable to follow up on abnormal results.

Additional Advice:

• Smokers should quit and be offered cessation support (counseling/medications).
• Eligible individuals should discuss screening with a doctor, including:
  • Benefits (early detection) and risks (false alarms, overtesting).
  • The need for yearly screenings to be effective.

This revision is crucial as it eliminates the 15-year since quitting requirement, which is often a detriment to determining lung cancer screening eligibility when it comes to insurance reimbursement. However, the United States Preventive Services Task Force (USPSTF) has still not adopted the 2023 ACS lung cancer screening guidelines, thus, Medicare and Medicaid still follow the 2021 USPSTF lung cancer screening guidelines.

The History of Lung Cancer Screening

Lung cancer screening refers to the testing of an individual who is at risk for developing lung cancer, but does not exhibit any signs or symptoms of the disease. Detecting lung cancer early, particularly at a stage when it is curable, can reduce mortality and significantly improve lung cancer outcomes.

The birth of cancer screening began in the United States at the start of the 20th century. In the 1920s, the periodic health exam for early disease detection was adopted into general medical practice, following the endorsement of the American Medical Association (AMA). A few decades later, in 1968, Dr. Wilson and Junger published a monograph on the Principles and Practice of Screening for Disease. This monograph outlines the fundamental principles to follow when deciding on a given screening test.

In the 1970s, three randomized clinical trials evaluated the impact of screening with chest x-rays or sputum cytology on lung cancer mortality. Due to the study's limitations, the results indicated no reduction in lung cancer deaths and even suggested increased harm in the screened population. Subsequently, several clinical studies began to assess low-dose computed tomography (LDCT) for lung cancer screening. The first large randomized trial to demonstrate the effectiveness of LDCT was the National Lung Screening Trial (NLST), which was reported to reduce lung cancer mortality by 20%. This study was published in 2011 and consisted of 53,454 participants aged 55 to 74 who had 30 or more pack-years of smoking history.

What is a chest low-dose computed tomography (LDCT)?

LDCT is a procedure that uses a computer linked to an X-ray machine to emit a very low dose of radiation, creating a detailed series of images of areas in the body. These images are taken from different angles to produce a three-dimensional view of the chest. It is also referred to as a low-dose chest CT scan. Major studies, such as the National Lung Screening Trial (NLST) and the NELSON trial, show that LDCT screening reduces lung cancer mortality by 20-24% by detecting tumors at earlier, more treatable stages. Some current challenges in clinical practice that are being addressed with this procedure include minimizing false positives and integrating smoking cessation programs.

Lung Cancer Risk Factors

Risk factors for lung cancer include increasing age, tobacco use (cigarettes, pipes, cigars), secondhand smoke exposure, and occupational and environmental hazards (asbestos, arsenic, radon). Prior radiation exposure from previously treated cancers also raises your risk, along with air pollution and family history. SCLC is strongly associated with cigarette smoking. To reduce risk, critical preventative measures like quitting smoking, testing homes for radon, limiting carcinogen exposure, and avoiding unnecessary radiation can be beneficial.

Addressing Health Disparities in Lung Cancer Screening

Lung cancer disproportionately affects underrepresented racial and ethnic populations in the United States. For instance, Black men have the highest incidence of new lung cancer cases among all U.S. racial and ethnic groups. Furthermore, populations with low socioeconomic status, who are often exposed to environmental risk factors, experience higher rates of lung cancer occurrence.

Lung cancer screening uptake remains low across the U.S. due to challenges such as limited access to screening, low patient acceptance, and a lack of physician knowledge about screening guidelines. Likewise, healthcare providers are less likely to counsel minority racial and ethnic groups and uninsured patients on smoking cessation.

Current screening guidelines do not equally serve all populations. For instance, Black individuals tend to develop lung cancer with fewer years of smoking than White individuals. In one study, the average was 16 pack-years for Black patients compared to 22 for White patients. But because the current guidelines use a strict 20 pack-year cutoff, many Black individuals at risk may be left out of screening. Future guidelines should expand eligibility criteria to better cover at-risk minority demographics. Also, expanding Medicaid coverage, reducing documentation burdens for providers, and improving rural healthcare access would ensure equitable screening and reduce lung cancer disparities.

Conclusion

The updated lung cancer screening guidelines are designed to help healthcare providers and patients identify those at higher risk for lung cancer with a history of smoking. Current recommendations support annual low-dose CT (LDCT) screening for people aged 50 to 80, who currently smoke or have quit within the past 15 years, and have a smoking history of 20 or more pack-years. Patients must engage in shared decision-making with a qualified health professional before screening. For those who still smoke, access to smoking cessation support should be part of the care plan. If adopted nationwide, these guidelines stand to significantly reduce lung cancer deaths.

Author

Jeffrey Velotta, MD, FACS

Cardiothoracic Surgeon at Kaiser Permanente

X: @JVelottaMD

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Works discussed

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