Cervical cancer screening & HPV vaccination Flashcards
What is the difference between SeNsitivity and SPecificity? (picmonic)
- SeNsitivity= % of people WITH the disease that your test will detect, (SNout rules OUT). SCREENING test.
- SPecificity= % of people WITHOUT disease that will test negative, (SPin rules IN).
Are sensitivity and specificity independent of incidence of disease?
YES. So if you apply these 2 tests to a population where there is greater or less incidence of disease, they will not change.
What is positive predictive value (PPV)? (picmonic)
% of people who TEST POSITIVE that actually HAVE the disease; true positive, (TP/TP+FP). This allows physicians to tell a pt who has tested positive for a disease, how likely it is that they actually have the disease.
What is negative predictive value (NPV)? (picmonic)
% of people who TEST NEGATIVE that do NOT HAVE the disease; true negative, (TN/TN+FN). This allows physicians to tell a pt who has tested negative for a disease, how likely it is that they actually do not have the disease.
What is a false negative?
% of people who HAVE the disease but test negative
What is a false positive?
% of people who do NOT have the disease but test positive
What is the sensitivity and specificity of a single PAP (not HPV test) at detecting high grade dysplasia?
- SeNsitivity= 38-59% (pretty BAD; ideally you want this as your SCREENING test to be above 80%).
- SPecificity= 87-96% (pretty GOOD)
- INDEPENDENT of disease prevalence
What are the predictive values of a PAP (not HPV test) at detecting high grade dysplasia?
- PPV= 25-51% (not good)
- NPV= 79-98% (GOOD)
- false negative= 2% (EXCELLENT)
- DEPENDENT on disease prevalence.
What is the sensitivity and specificity of a single HPV test at detecting high grade dysplasia?
- SeNsitivity= 76-96% (pretty GOOD).
- SPecificity= 93% (pretty GOOD)
- INDEPENDENT of disease prevalence
What was one of the first big studies that shaped the way our guidelines work for cervical cancer screening?
the Athena study
Has cervical cancer screening helped since 1975 in the U.S.?
YES. Incidence and mortality have dropped :)
Why do Americans still get cervical cancer?
- under-screening/follow-up
*** What are the current guidelines for cervical cancer screening? (KNOW)
- less than age 21= do NOT screening
- age 21-29= pap q3 yrs; only cytology unless abnormal, then triage HPV testing.
- age 30-65= pap + HVPV q5 yrs (preferred) -OR- pap q3 yrs (acceptable).
- after age 65= acceptable to stop screeing
- after TOTAL hysterectomy (uterus+cervix)= stop stop screening if: hysterectomy was not for dysplasia, 3 consecutive normal paps within 10 yrs, or no h/o CIN (cervical intraepithelial neoplasia) within 20 years.
Why don’t we screen women under age 21 for cervical cancer?
- less than 0.1% of cases of cervical cancer occur before age 21.
- most HPV infection is cleared by immune system within 18 months w/o producing neoplastic change.
Why do we screen every 3 years from age 21-29?
- the small increase in life-time cervical risk is negligible compared to doing it every year. We also want to reduce doing unnecessary tests, which this would fall into doing it every year.
Why do we change from every 3 years to every 5 years at age 30?
- HPV infection after age 30 is more likely to reflect persistent rather than new infection. So you can wait every 5 years as long as you are adding the pap smear.
- however most recent study suggests that HPV testing alone after age 30 may be sufficiently sensitive as primary screening.
How do screening guidelines change in HIV+ women?
- pap 2x within 1 yr of HIV diagnosis (aka every 6 months).
- for adolescents, start at age of sexual activity and do annually.
Does cervical cancer screening change for lesbians?
- No. HPV can be spread from female-female sexual contact.
* however they are at a lower risk of contracting other STIs.
What is a problem with transgender men (female-to-male)?
- they are 8x more likely to have inadequate paps, bc during their transition they make a lot of androgens and this makes their pap readings difficult.
What are some important techniques when performing the pap smear?
- always want to SEE the cervix (NEVER do a blind pap).
- use spatula to collect cells from ECTOcervix and a cytobrush for the ENDOcervix. USE LUBE!!! When complete, break off the tips of the spatula and cytobrush and leave in solution to be sent to lab.
