Epidemiology & Prevention USMLE Step 1 Practice Question
A 45-year-old woman with no significant medical history presents for routine breast cancer screening mammography. The examination is interpreted as BI-RADS 4 (suspicious for malignancy), and she is referred for ultrasound-guided biopsy. Pathology returns benign fibrocystic changes. The radiologist notes the mammography has 90% sensitivity and 85% specificity for detecting breast cancer in women aged 40-50 years. The patient asks why a positive mammogram did not definitively confirm she had cancer. Which of the following best explains this result?
Answer choices
- ASensitivity and specificity are properties of the test that vary based on whether it is used for screening versus diagnostic purposes
- BThe positive predictive value of mammography depends on the prevalence of breast cancer in the screened populationCorrect answer
- CThe specificity of 85% is too low; mammography should only be used if specificity exceeds 95%
- DNegative predictive value is a more clinically relevant parameter than positive predictive value for cancer screening
- EThe test's 90% sensitivity indicates that 10% of women without breast cancer will test positive
- FFibrocystic changes cannot be reliably distinguished from malignancy on mammography alone
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