TABLE 2.

Historical Rationale for Discontinuing Collection of Cervical Intraepithelial Neoplasia 3 and Cervical Carcinoma In Situ: Conclusions and Recommendations by the American Association for Cancer Research Uniform Data Standards Committee: Subcommittee on Noninvasive Cervix Lesions, 1993^*

Conclusions
1.	Data on preinvasive cervical neoplasia as currently collected by US registries are no longer comparable historically for monitoring trends over time and cannot be made to be comparable. The problem will get worse as the Bethesda System (TBS) is adopted more widely for histopathology. Collection of only the term carcinoma in situ (CIS) yields undercounts in recent data compared with the past. Collection of both of the terms CIS and cervical intraepithelial neoplasia 3 (CIN-3) yields over counts compared with the past.
2.	In the future, it will not be possible in every case to distinguish moderate dysplasia, severe dysplasia, and CIS on pathology reports.
3.	There is evidence that the relative use of the 3-tier, 4-tier, and TBS systems varies from place to place within the US. Thee comparability of current data across registries is limited by different rates of differences in terminology used on pathology reports.
4.	Data as collected presently can be used to monitor differences in subpopulations within a geographic area as long as biases in diagnostic criteria and case ascertainment are not present. Preinvasive rates help to interpret differences in invasive rates, and in situ/invasive ratios in particular appear to have implications for prevention activities.
5.	Adjacent grades of preinvasive lesions are more difficult to distinguish from one another and are less reproducible than the distinction between invasive and noninvasive lesions.
6.	Treatment is becoming more conservative and more uniform for high-grade squamous intraepithelial lesion (HSIL) and the other equivalent terms. Because colposcopic biopsy and loop electrosurgical excision procedures can be therapeutic as well as diagnostic, histologic diagnoses of preinvasive lesions represent cancer control interventions. Fewer ablative procedures will be done without tissue diagnosis, so this is not expected to be a significant source of missed cases.
7.	Diagnosis and treatment, as also is true to some extent for other cancer sites, are moving out of the hospital setting. It will become more and more difficult and expensive to find cases and collect required demographic data, such as the patient’s race and place of residence. Out of area laboratories likely be a problem and will be an increasingly important source of missed cases.
8.	The Surveillance, Epidemiology, and End Results Program, which sets the de facto reporting standard in this area, likely will drop collection of CIS and CIN-3 in all areas and instead, with special funds, will expand collection to include HSIL and its equivalent terms in selected areas.
Recommendations
1.	The only way to collect histologic data that would be comparable over time in the future is to collect all HSIL and all of its equivalents in the 3- and 4-tier systems. This would increase the number of preinvasive cervix uteri cases in a registry that currently collects CIS and CIN-3 by approximately 2- to 3-fold; however, the new data would not be comparable to data collected earlier.
2.	For research on the natural history of this disease, special studies that include the entire spectrum of low-grade squamous intraepithelial lesion (LSIL) and HSIL will be necessary.
3.	Population-based registries need to assess locally the anticipated uses of the data (are time trends desirable? Are comparisons to data from other areas needed? Will cancer control programs use the data), present and future pathology practices in their areas (Will TBS be used for histopathology?), and available resources (can the registry afford to collect substantially more cases?) and decide whether to: a. Collect CIS, CIN-3, and severe dysplasia, which will not be possible if TBS is used for histopathology; or b. Collect all HSIL and its equivalent terms in the 3- and 4-tier systems, which will substantially added to the caseload; or c. Drop the collection of all data for all but invasive cervical cancers.
4.	The subcommittee strongly recommends that population-based registries discontinue routine collection of data on preinvasive cervical neoplasia unless there is strong local need and interest and sufficient resources are available to collect all HSIL and its equivalent terms.

^*2008 Updates: 1) TBS categories have changed from 2-tiered (low grade and high grade) to multiple tiers (atypical squamous cells of undetermined significance [ASC-US]; ASC-US, cannot rule out HSIL; atypical granular cells; LSIL; and HSIL); 2) CIN-3 plays a larger role among the in situ cancers for the 1 registry that has continued collection of this variable (Michigan); 3) TBS is recommended for cytology and the 3-tiered system (CIN-1, CIN-2, and CIN-3) usually is reserved for histology; 4) there still may be pathologists who use the 2-tiered system (low grade and high grade) for histology; and 5) there still may be pathologists who use the dysplasia categories (mild, moderate, severe) for histology.