SUMMARY:

The current USPSTF guidelines recommend annual cancer screening using low-dose CT. Lung cancer has a poor prognosis and is the third most common type of non-skin cancer in the United States. Lung cancer is the leading cause of cancer death in men and in women. The USPSTF recommends (Grade B – offer or provide this service)

Screen annually for lung cancer with low-dose computed tomography

Discontinue screening when the patient has not smoked for 15 years

Population

Asymptomatic adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit smoking within the past 15 years

Risk Factors for Lung Cancer

• Most important factors
  • Age | Incidence relatively low in individuals under 50 and increases with age, especially >60 years
  • Total cumulative exposure to tobacco smoke
  • Years since quitting smoking
• Additional risk factors
  • Specific occupational exposures
  • Radon exposure
  • Family history
  • History of pulmonary fibrosis or chronic obstructive lung disease

Screening Tests

• Low-dose CT
  • High sensitivity and acceptable specificity in high-risk populations persons

Balance of Benefits vs Harms

• Annual screening for lung cancer with low-dose CT is of moderate net benefit in asymptomatic persons who are at high risk for lung cancer based on age, total cumulative exposure to tobacco smoke, and years since quitting smoking

KEY POINTS:

Evidence of Benefit for low-dose CT

• Large RCT – National Lung Screening Trial (NLST) is cited as the study demonstrating clinical utility
• Participants
  • 55 to 74 years
  • Cigarette smoking histories of ≥30 or more pack-years and who, if they are former smokers, have quit within the last 15 years
• Results: Low-dose CT
  • Reduces lung cancer mortality by 20% (95% CI, 6.8–26.7; P = .004)
  • Reduces all-cause mortality by 6.7% (95% CI, 1.2–13.6; P = .02)
  • Updated analysis: Lung cancer reduction of 16%

• Harms
  • Primarily harm is risk for false-positive low-dose CT | Majority of positive results do not lead to a diagnosis and up to 96% of positive exams may not result in cancer detection | In a high-quality screening program, further imaging can resolve most, although not all, false-positive results
  • Overdiagnosis can be up to 25% depending on screening population (NCI)
  • Radiation Exposure from CT 

The NELSON Trial (NEJM, 2020)

• The NELSON RTC demonstrated that at 10 years of follow-up, screening with volume CT imaging
  • Reduced lung-cancer mortality by 24% among men and by 33% among women in high risk populations
  • Reduced overdiagnosis to 10%
  • Improved PPV to 43.5%

Calculating Pack-Years

• Calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked
  • 1 pack = 20 cigarettes
• Examples
  • 1 pack (20 cigarettes) per day for 1 year = 1 pack-year
  • 2 packs (40 cigarettes) per day for half a year = 1 pack-year
  • ½ pack (10 cigarettes) per day for 20 years = 10 pack-years

Recommendations of Other Professional Societies

• American Society of Clinical Oncology
  • People age 55 to 74 who have smoked for 30 pack-years or more | Also recommended for those age 55 to 74 who have quit within the past 15 years
  • CT screening not recommended: Smoked for less than 30 pack-years | Younger than 55 or older than 74 | Quit smoking more than 15 years ago | Have a serious condition that could affect cancer treatment or shorten a person’s life

• The American Association for Thoracic Surgery
  • Age 55 to 79 years with ≥30 pack-year smoking history
  • Long-term lung cancer survivors who have completed 4 years of surveillance without recurrence, and who can tolerate lung cancer treatment in order to detect second primary lung cancer until the age of 79
  • Age 50 to 79 years with a 20 pack-year smoking history and additional comorbidity that produces a cumulative risk of developing lung cancer ≥5% in 5 years
• American College of Chest Physicians
  • Age 55 to 77 years with ≥30 pack-year smoking history and either continue to smoke or have quit within the past 15 years
• NCCN
  • Age 55 to 77 with ≥30 pack-year smoking history and smoking cessation <15 years
  • Age ≥50 years and ≥20 pack-year history of smoking and additional risk factors that increase risk of lung cancer to ≥1.3%
• American Cancer Society
  • Age 55 to 74 years, currently smoke or have quit within the past 15 years, and
  • Have at least a 30-pack-year smoking history

Learn More – Primary Sources:

USPSTF: Lung Cancer Screening

Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening: The National Lung Screening Trial

NEJM: Reduced Lung-Cancer Mortality with Volume CT Screening in a Randomized Trial

NCI: Lung Cancer Screening (PDQ®)–Health Professional Version

Evaluation of USPSTF Lung Cancer Screening Guidelines Among African American Adult Smokers

NCI: Pack-Year Definition

Screening for Lung Cancer: Diagnosis and Management of Lung Cancer, 3rd ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

Lung Cancer Screening Guidelines: Most Commonly Referenced Lung Cancer Screening Guidelines (Society of Thoracic Surgeons)

NCCN Lung Cancer Screening

ASCO Screening Information for Lung Cancer