Grand Rounds: Part 1: Cervical cancer guidelines: Making sense of the screening intervals

What's everybody waiting for? It's been roughly 3 years since the American Cancer Society (ACS) and the American College of Obstetricians and Gynecologists (ACOG) issued new primary cervical screening guidelines.^1,2 So why are so many of us still struggling with how best to integrate them into our practices? The answer lies in how radically several guidelines depart from the status quo. Clinicians and the public alike have become accustomed to-and maybe too comfortable with-the standard practice that became entrenched after cervical screening guidelines were introduced in the late 1970s and updated in 1988.³ Long tradition and familiarity with these established guidelines for a quarter of a century has made rapid acceptance of new approaches to screening all the more challenging.

Further roadblocks to getting past business-as-usual screening patterns have been the 2004 "Interim Guidance on the use of HPV testing in primary screening" and the 2005 ACOG Practice Bulletin Number 61.^4,5 [Despite this information overload, it's imperative for clinicians to understand the rationale behind each guideline and how to apply each to routine patient management.] The new guidelines advise when to begin screening, the differing screening intervals once you do begin, and when to cease screening. My goal in this first installment of a two-part article is to review the changes in screening intervals-addressing when and how often to screen and the rationale behind the changes-and to illustrate them with case studies on how to integrate the guidelines into your practice. I will use similar case studies in Part 2, which will focus on combining HPV screening with Pap tests.

When to begin screening

In contrast to this very low risk for cervical cancer, the risk for acquiring HPV in the late teens and early 20s is very high. For example, 44% of teens in a UK study between ages 15 and 19 tested positive for HPV at least once during a 3-year period and 60% were positive by 5 years.⁷ Similar results have been found in studies of young women in our own country (Figure 1).^8,9 This very high rate of HPV infection results in high rates of minor Papanicolaou (Pap) abnormalities reported as HPV-positive atypical squamous cells of undetermined significance (ASC-US) and as low-grade squamous intraepithelial lesions (LSIL).¹⁰ However, most of these low-grade cytologic changes are transient, disappearing in step with successful immune suppression of the virus that caused them. Most women infected with HPV will have a favorable outcome: a return to an HPV-negative state for that same HPV type within 6 to 12 months of first HPV detection.⁹