In my last blog I talked about the considerable value of an internal consensus conference. This blog briefly addresses an important external consensus conference run by the CAP and the ASCCP (American Society for Colposcopy and Cervical Pathology), termed the Lower Anogenital Squamous Terminology Standardization Project, or LAST project for short.
The LAST project has been a two-year effort to unify diagnostic terminology for HPV-associated squamous intraepithelial lesions and superficially invasive carcinomas and to define the appropriate use of biomarkers in this setting. The July 2012 issue of the CAP Today contains an excellent review on this topic. The specific recommendations were also published in the Archives of Pathology and Laboratory Medicine.
The most important recommendations can be divided into three groups:
1. SQUAMOUS INTRAEPITHELIAL NEOPLASIA.
*The group recommended adoption of the Bethesda system of a two-tiered nomenclature, LGSIL and HGSIL, which optionally may be followed by the appropriate -IN three-tier designation (CIN, VIN, VAIN, etc).
2. SUPERFICIALLY INVASIVE SQUAMOUS CELL CARCINOMA (SISCCA).
*Use the term SISCCA for minimally invasive squamous cell carcinomas of the lower anogenital tract that are completely excised and "may be amenable to conservative therapy." (More site-specific details are available elsewhere.)
3. USE OF BIOMARKERS IN HPV-RELATED SQUAMOUS LESIONS.
*Use p16 to help distinguish dysplasia from mimics (atrophy, metaplasia, etc.)
*Use p16 to clarify borderline distinctions (LGSIL v. HGSIL)
*UDo not use p16 for histologically negative, obviously low-grade, or obviously high-grade lesions.
*Consider using p16 in patients with HGSIL Pap smears and apparently "normal" cervical biopsies.
With regard to the first recommendation, the drop from 3-tiered system to a 2-tiered system puts biopsy diagnoses in line with the Bethesda system for cervical cytology. Yet, this approach was the only one in the LAST project that encountered some considerable push-back, mainly from clinicians who were concerned that it might force their hand with regard to treating patients with small foci of CIN II who they, for a variety of reasons, would have preferred to follow. Thus, the note regarding the option for including the 3-tier -IN designation was added as a compromise toward the end of the project.
The project also makes it clear that p16 is currently the best available marker for assisting in defining dysplasia, but that it has a defined role and should not be over used (estimates suggest fewer than 20% of cases, probably much fewer, require p16). In addition, the project saw no need for a panel of markers (Ki67, ProEx C, etc) in this regard.