ASC, TBS, and the power of ALTS.

In this issue of the Journal, Lee and colleagues 1 from Hong Kong describe their assessment of the impact of the 2001 Bethesda System (TBS) revisions on their cytology practice. The primary focus of the study was to assess the impact of the conversion from TBS 1991 to the 2001 version on the frequency of atypical squamous cells (ASC) diagnoses. As noted in prior commentaries, ASC is not a diagnosis. ASC is a poorly reproducible mixture of reactive and inflammatory changes that mimic squamous intraepithelial lesion (SIL) in a group of patients who have SIL, mostly low grade (ASC-US [undetermined significance]) but perhaps 5% to 10% high grade (ASC-H). 2-6 So, can changes in classification terminology and criteria impact how much we equivocate? Let's see. Cases of ASC were retrospectively correlated within their computerized database for higher-grade end points including low-grade SIL (LSIL)/cervical intraepithelial neoplasia (CIN) 1, HSIL/CIN 2 or 3, or carcinoma based on routine practice. Fourteen cytopathologists and an undetermined number of cytotechnologists were involved in this study, which basically compared 28,000 cases from July 2000 to June 2002 when TBS 1991 was used with a similar number of cases in the 2-year period from July 2002 to June 2004. The major conclusion in this study was that the conversion to TBS 2001 led to a small but statistically significant increase in the specificity of the ASC diagnostic category and virtually all other diagnostic rates were unchanged. Is this really an important finding? And does it support the conversion to TBS 2001 as an important advance, as the authors suggest? Unfortunately, the comparisons in this article are confounded by multiple variables. The terminology conversion undoubtedly had a learning curve such that the application of the revised criteria early in the second observation period may have yielded different rates compared with when the operators were more familiar with the criteria later in the study. Regrettably, few time trend data are included. It is important to note that the terminology conversion was also associated with the implementation and partial conversion from conventional spray-fixed Papanicolaou smears to liquid-based cytol-ogy preparations. In the detail of the report it is also noted that the collection devices used for conventional cytology included only the spatula and no endocervical sampling device compared with the broom device used for liquid-based cytology preparations. In addition, the period of study was associated with a region-wide campaign to increase …