CASE: Erratic screening history with at least 1 abnormality
G.A., 40, vaguely remembers having at least 1 abnormal Pap test about 20 years ago. She is not sure exactly what the result was, but does recall that she underwent colposcopy. Her physician at the time told her that nothing important was detected and encouraged her to get “regular Pap tests” in the future. She followed this advice for several years, but her Pap tests became much less frequent after her 2 children were born. Today, she reports that her last Pap test was at least 5 years ago, but she does not remember exactly when. She also remembers being notified that she needed to repeat it, but is not sure why. Her records are unavailable because she has moved a lot and cannot remember the name of the doctor who saw her.
Today, G.A. is screened with both a Pap test and a human papillomavirus (HPV) test for high-risk viral types. The physician outlines the benefits of doing both tests and explains the “commonness” of HPV, offering reassuring facts about its natural history to “soften the concern” in the event she is found to be positive.
The Pap test comes back as “negative for intraepithelial neoplasia or malignancy” (ie, normal), but her HPV test is positive.
What questions is G.A. likely to raise? How can her risk of cervical cancer be quantified? And how should she be managed?
Why do an HPV test with the Pap?
G.A.’s situation is not unusual. Many women provide a vague history that includes 1 or more abnormal Pap tests in the distant past, with “probably normal” results on infrequent, irregular screening in more recent years.
It has been estimated that annual lifetime screening with a Pap test sensitivity of 70% for cervical intraepithelial neoplasia (CIN) 2 or 3 reduces the lifetime risk of cervical cancer by 93%. That means that even diligent lifetime screening will leave some women unprotected.1
The risk increases for women who are not screened regularly, especially those with a history of an abnormal Pap test. Approximately 10% of cervical cancers occur in women who have been screened in the past but not within the past 5 years.2
Pap test alone has poor sensitivity
A number of meta-analyses have documented the sensitivity of the conventional Pap smear for the detection of CIN 2,3 to be between 51% and 67%.3,4 And although liquid-based cytology offers many advantages, early reports of improved sensitivity over conventional cytology were not substantiated in a 2006 meta-analysis of a large number of studies (as reported in Update on Cervical Disease, by Thomas C. Wright, MD, in the March issue of OBG Management).5
Despite the low sensitivity of cervical cytology, Pap test screening has been extremely successful in detecting precancerous cervical changes and allowing timely treatment. The success is directly attributable to repeated screening of women during the relatively slow progression from initial HPV infection to CIN 3 (typically, about 10 years) and from CIN 3 to cancer (typically, 10 or more years).6 Poor sensitivity raises concern, however, when screening attendance is not ideal.
Together, the tests lower the risk of missing CIN or cancer to 1 in 1,000
Surely, G.A. would benefit by having the most reassuring screening available. Guidelines from the American Cancer Society (2002) and 2 practice bulletins from the American College of Obstetricians and Gynecologists (ACOG) (2003, 2005) recommend as 1 of 2 options screening women age 30 and over with both the Pap test and the HPV test for high-risk types. 7-9
A 2005 ACOG practice bulletin on HPV10 noted the reassurance offered by combined testing and observed that, based on Level A evidence, “HPV testing is more sensitive than cervical cytology in detecting CIN 2 and CIN 3, [so] women with concurrent negative test results can be reassured that their risk of unidentified CIN 2, CIN 3, or cervical cancer is approximately 1 in 1,000.”
Most women would benefit from a screening test that provides a reassurance of 1 in 1,000. Given G.A.’s infrequent screening history, previous abnormal cervical cytology, and unknown result on her last screen over 5 years ago, using the most reassuring combination of tests would seem to be imperative.