What is the best screening test for a heavy smoker (smoking history) coming for a general examination?

Best Screening Test for a Heavy Smoker

For a heavy smoker coming for general examination, the answer depends critically on age and sex: men aged 65-75 who have ever smoked should receive one-time AAA screening with ultrasonography (Grade B recommendation), while individuals aged 50-80 with ≥20 pack-year smoking history should receive annual low-dose CT lung cancer screening—and if both criteria are met, both screenings should be offered. 1

Primary Screening Priority by Demographics

For Men Aged 65-75 Years Who Have Ever Smoked

• One-time abdominal aortic aneurysm (AAA) screening with ultrasonography is the priority, as it reduces AAA-specific mortality based on good evidence, with screening and surgical repair of large aneurysms (≥5.5 cm) leading to decreased AAA-specific mortality. 1, 2
• The benefits of AAA screening outweigh the harms (including increased surgeries with associated morbidity/mortality and short-term psychological harms) in this specific population. 1
• Smoking is the strongest risk factor for AAA, with an odds ratio of 5.57 for AAAs ≥4.0 cm, and smoking accounts for 78% of all clinically important AAAs. 3
• Abdominal ultrasonography performed in an accredited facility with credentialed technologists is an accurate screening test for AAA. 1

For Any Gender Aged 50-80 Years with ≥20 Pack-Year Smoking History

• Annual low-dose CT (LDCT) screening for lung cancer is indicated if the patient currently smokes or quit within the past 15 years. 4, 5, 1
• LDCT reduces lung cancer mortality by 20% and all-cause mortality by 6.7%, with a number needed to screen of approximately 320 to prevent one lung cancer death over 6.5 years. 4, 1
• The sensitivity of LDCT is 93.8% with specificity of 73.4%, substantially superior to chest radiography. 4
• LDCT screening should only be offered when the patient is healthy enough to undergo curative lung surgery if cancer is detected, and screening must occur within a dedicated program with quality control and multidisciplinary management. 4

Critical Implementation Algorithm

Step 1: Determine if patient meets AAA screening criteria

• Male, aged 65-75, ever smoked → One-time AAA screening with ultrasonography 1, 2
• Male, aged 65-75, never smoked → Selective AAA screening (discuss with patient) 2

Step 2: Determine if patient meets lung cancer screening criteria

• Any gender, aged 50-80, ≥20 pack-years, current smoker or quit ≤15 years → Annual LDCT lung cancer screening 4, 5, 1
• Older criteria (still valid): aged 55-80, ≥30 pack-years, current smoker or quit ≤15 years 6

Step 3: If both criteria met

• Offer both AAA screening (one-time) and annual LDCT lung cancer screening 1

Step 4: Mandatory concurrent intervention

• All heavy smokers must receive aggressive smoking cessation counseling with combination pharmacotherapy and behavioral interventions, as this remains the single most effective intervention to prevent both lung cancer and AAA mortality. 4, 1

Technical Specifications for LDCT

When ordering LDCT lung cancer screening:

• Use appropriate diagnostic code Z87.891 for personal history of tobacco use 5
• LDCT parameters: 120-140 kVp, 20-60 mAs, average effective dose ≤1.5 mSv 4, 5
• Document patient's age, smoking history in pack-years, current smoking status or years since quitting, and absence of symptoms suggestive of lung cancer 5

Important Caveats

For lung cancer screening:

• The positive predictive value for a pulmonary nodule ≥4 mm is only 3.8%, meaning 96.4% of positive results are false-positives over 3 rounds of screening. 6
• Most positive results require only additional imaging, but approximately 2.5% require invasive diagnostic procedures. 6
• Overdiagnosis occurs in 9.5% to 11.9% of screen-detected cancer cases. 6

For AAA screening:

• The prevalence of AAA in screened populations has declined over the past 2 decades, but smoking remains the dominant risk factor. 2, 3
• Current smoking status is the most significant risk factor (OR 6.33 for females, OR 2.50 for males compared to never smokers). 7
• The association between smoking and AAA increases with years of smoking and decreases with years after quitting. 3

Regarding Colon Cancer Screening (Option B)

While colon cancer screening is important for all adults aged 45-75 years regardless of smoking status, smoking is not a specific indication that prioritizes colon cancer screening over AAA or lung cancer screening. The question asks for the "best" screening test for a heavy smoker specifically, and both AAA and lung cancer screening have smoking as their primary risk factor with specific evidence-based guidelines targeting this population. 6, 4, 1, 2

Therefore, the answer is C (AAA) if the patient is a male aged 65-75, or lung cancer screening if aged 50-80 with ≥20 pack-years—with both being appropriate if criteria overlap.