Breast Cancer Screening: A Primary Care Perspective Flashcards
Screenings, by definition, are only in people without ______________.
symptoms; if they have symptoms, that is a diagnostic test
What happens to early-stage incidence and late-stage incidence when screening protocols are implemented?
Early-stage incidence increases and late-stage incidence decreases.
Breaking down cancers into very fast, fast, slow, and very slow progressors, what cancers are you hoping to find with screening?
Fast
Note: Over-diagnosis occurs in the slow and very slow cancers (like prostate cancer) and screening is unlikely to catch the very fast progressors (like melanoma).
What is lead-time bias?
If you discover something earlier then it appears that people in the screened group live longer.
What is length-time bias?
You’re more likely to discover something that’s slow growing.
In a 2x2 table, the _____________ is on top.
positive (those who have the disease)
Why is high sensitivity important in a screening test?
High sensitivity means you have few false negatives, which is important if you’re going to tell people they don’t have a disease.
What is the SpIn mnemonic?
With a highly SPecific test, you’ve ruled the patient IN. This is so because with high specificity you have few false positives.
What is the formula for NPV?
(TN) / (TN + FN)
What is the likelihood that a woman with an abnormal mammogram has breast cancer?
6.6%
As the prevalence of a certain disease goes down, the rate of ______________ goes up.
false positives
What is the prevalence of breast cancer in women in their 40s and 50s?
40s: 1%
50s: 2%
What is the likelihood ratio?
(probability of test result in person with disease)
_____________________________________
(probability of same result in person without disease)
What are good LRs for ruling something in and out?
In: greater than 10
Out: less than 0.1
What are the formulae for LR + and LR -?
LR +:
(sensitivity) / (1 –specificity)
LR –:
(1 –sensitivity) / (specificity)
