Chapter 2-9: Lung Cancer Screening

What is the burden of disease?

1. Lung cancer is the leading cause of cancer death in both men and women.

2. About 150,000 deaths from lung cancer in 2018, more than the number of deaths from breast, prostate, and colon cancer combined.

3. Prognosis of non–stage I lung cancers is poor.

Is it possible to identify a high-risk group that might especially benefit from screening?

1. Cigarette smoking is responsible for about 85% of lung cancers.

   1. Compared with nonsmokers, relative risk of developing lung cancer is about 20.

   2. A 65-year-old who has smoked 1 pack/day for 50 years has a 10% risk of developing lung cancer over the next 10 years.

   3. A 75-year-old who has smoked 2 packs/day for 50 years has a 15% risk.

2. Other risk factors include family history of lung cancer and exposure to asbestos, nickel, arsenic, haloethers, polycyclic aromatic hydrocarbons, and environmental cigarette smoke.

What is the quality of the screening test?

1. Chest radiograph: sensitivity, 60%; specificity, 94%

2. CT scan: sensitivity, 94%; specificity, 73%

Does screening reduce morbidity or mortality?

1. Chest radiograph: 6 randomized trials of chest radiography, with or without sputum cytology, failed to demonstrate a decrease in lung cancer mortality; all were limited by the control population undergoing some screening.

2. CT scan: National Lung Screening Trial (NLST)

   1. Over 53,000 asymptomatic persons aged 55–74 with ≥ 30 pack year smoking history; former smokers must have quit within the past 15 years

   2. Exclusions: previous lung cancer, other cancer within the last 5 years, CT scan within the last 18 months, metallic implants in the chest or back, home oxygen use, pneumonia, or other acute upper respiratory tract infection treated with antibiotics within the last 12 weeks

   3. Randomized to 3 annual screenings with low-dose CT scan or single view posteroanterior chest film; an abnormal screen was defined as a nodule ≥ 4 mm

   4. Lung cancer–specific mortality was significantly reduced in the low-dose CT group.

      1. CT group lung cancer mortality rate = 1.3%, compared to 1.6% in the chest film group

      2. Relative risk reduction = 20%; absolute risk reduction of 3 lung cancer deaths per 1000 patients screened with CT; number needed to screen to prevent 1 lung cancer death = 320

   5. Nearly 40% of participants had at least 1 positive CT result; 96% of these were false-positives. Most false-positive results were resolved by follow-up CT scans, although some patients required biopsies.

What are the current guidelines?

1. USPSTF (2013)

   1. Annual screening with low-dose CT in adults ages 55–80 who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years.

   2. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem substantially limiting life expectancy or ability to have curative lung surgery.

   3. Grade B recommendation

2. The American College of Chest Physicians recommends offering annual screening with low-dose CT to asymptomatic smokers and former smokers age 55–77 who have smoked 30 pack years or more and either continue to smoke or have quit within the past ...