Master Preventive Medicine
for USMLE Step 2 CK

What the USMLE Step 2 CK Tests in Preventive Medicine

Preventive Medicine on USMLE Step 2 CK tests your ability to apply evidence-based screening, immunization, and counseling in asymptomatic populations. You must know age- and risk-based screening intervals for cancers (colon, breast, cervix, lung, prostate), cardiovascular risk assessment (Framingham, ASCVD), and diabetes (HbA1c, fasting glucose). Immunization schedules (CDC/ACIP) for children, adults, and special groups (pregnancy, asplenia, travel) are core. Chemoprophylaxis (aspirin, statins, tamoxifen) and lifestyle counseling (smoking cessation, alcohol, obesity) appear frequently. Questions often present a patient with a risk factor (e.g., family history, smoking) and ask the next best preventive action or the USPSTF grade recommendation.

High-Yield Concepts

• Colorectal Cancer Screening: Average-risk adults: start at age 45 (USPSTF 2021). Options: colonoscopy every 10 years, FIT annually, CT colonography every 5 years, or flexible sigmoidoscopy every 5 years. For high-risk (e.g., first-degree relative with CRC before age 60): start at age 40 or 10 years before relative's diagnosis, typically colonoscopy every 5 years.
• Breast Cancer Screening: Average-risk women: biennial mammography from age 50 to 74 (USPSTF grade B); shared decision-making for ages 40-49 (grade C). High-risk (e.g., BRCA mutation, strong family history): annual mammography and breast MRI starting at age 30 or as per genetic counseling.
• Cervical Cancer Screening: Start at age 21. Ages 21-29: Pap smear every 3 years. Ages 30-65: Pap + HPV co-testing every 5 years (preferred) or Pap alone every 3 years. Stop after age 65 if adequate prior screening and no high-risk history. HPV vaccination does not change screening intervals.
• Lung Cancer Screening: USPSTF: annual low-dose CT for adults aged 50-80 with ≥20 pack-year smoking history, currently smoking or quit within 15 years. Discontinue when >15 years since quitting or age >80.
• Cardiovascular Risk Assessment and Statin Chemoprophylaxis: Use ASCVD risk calculator (Pooled Cohort Equations). Statin indicated for primary prevention if: age 40-75, LDL 70-189 mg/dL, 10-year risk ≥7.5% (moderate-intensity statin) or ≥20% (high-intensity). Also for patients with diabetes (age 40-75) or LDL ≥190 mg/dL.
• Aspirin for Primary Prevention: USPSTF 2022: consider low-dose aspirin (75-100 mg daily) for adults aged 40-59 with 10-year ASCVD risk ≥10% and no increased bleeding risk (grade B). Not routinely recommended for age ≥60 due to bleeding risk (grade D).
• Immunization Schedule Key Points: Adults: Tdap once (then Td or Tdap every 10 years), influenza annually, pneumococcal (PCV15 or PCV20 for age ≥65 or high-risk), shingles (RZV, 2 doses for age ≥50), COVID-19 as per current guidelines. Children: MMR at 12-15 months and 4-6 years; HPV vaccine series starting at age 11-12 (catch-up through age 26).
• Osteoporosis Screening and Vitamin D: DXA scan for women ≥65, or younger if FRAX 10-year risk ≥ major osteoporotic fracture >9.3%. Treat with bisphosphonates (e.g., alendronate) if T-score ≤ -2.5 or history of fragility fracture. Vitamin D supplementation: 600-800 IU/day for adults ≥70, but no routine screening for deficiency in asymptomatic adults.

Common Traps in Preventive Medicine Questions

• Confusing USPSTF grades: Grade B means recommended, Grade C means offer selectively based on professional judgment, Grade D means not recommended — do not equate C with 'do not do'.
• Assuming screening intervals are the same for high-risk patients (e.g., colonoscopy every 3 years for Lynch syndrome, not 10 years).
• Forgetting that cervical cancer screening stops at age 65 only if adequate prior negative screens (three consecutive negative Pap or two negative co-tests within 10 years).
• Recommending aspirin for primary prevention in patients over 60 without checking bleeding risk (gastritis, anticoagulation, history of GI bleed).
• Using the older Framingham risk score instead of the ASCVD Pooled Cohort Equations for statin decisions on USMLE.
• Omitting the catch-up window for HPV vaccination: up to age 26 for both sexes, and up to age 45 only after shared decision-making.

How to Revise Preventive Medicine for the USMLE Step 2 CK

Prioritise memorising USPSTF screening ages and intervals for breast, cervical, colorectal, lung, and prostate cancers. Know the ASCVD risk cut-off (7.5%) for statin initiation and the bleeding risk contraindications for aspirin. Immunization schedules appear in clinical vignettes—focus on catch-up doses for adults (e.g., Tdap in pregnancy, HPV up to 26). Questions are often framed as 'which one test or intervention is most appropriate now?'—avoid over-screening (e.g., DXA before age 65 without risk factors). Practise applying the USPSTF grade to decide between screening and not screening. Use the 'number needed to screen' concept rarely; instead, rely on absolute recommendations.

Practise it: MedLumen has 50 Preventive Medicine questions for the USMLE Step 2 CK, each with a full explanation and references.