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CMAJ
CMAJ - June 2, 1998JAMC - le 2 juin 1998

More on breast cancer guidelines

CMAJ 1998;158:1427

See response from: M. McGregor
Overall, this is an excellent, much-needed document. However, I was disappointed by some of the comments about the pathologic interpretation for diagnosis of DCIS. Specifically, on page S30, the authors indicate a high rate of misinterpretation of ADH and DCIS and imply a high rate of misinterpretation by general pathologists working in the community.

As a general pathologist, I believe that 3 points need further clarification. First, I agree that distinguishing between ADH and low-grade DCIS is a problem, specifically in the case of borderline lesions between these 2 entities. Even among experienced pathologists with an interest in breast pathology, there may be a lack of concordance in such cases.1 However, when pathologists use standardized criteria to classify these lesions, concordance is much better.2 A recent consensus conference on the classification of DCIS3 recommended a universally acceptable, reproducible and clinically useful system of classification, but such is not currently available.

Second, in response to the recommendation that biopsy specimens examined by relatively inexperienced pathologists be reviewed by pathologists with special expertise in this area, I think that most general pathologists do see ample cases of breast cancer to maintain their expertise — breast biopsy is one of the most common procedures performed in the community. Most cases of DCIS, especially the higher-grade, comedo type, pose no special problem. The problems arise with low-grade DCIS, as described earlier, and the borderline cases will continue to pose a problem, even for experienced pathologists with an interest in this area.

Finally, the statement that the pathology assessment is critical not only to the diagnosis of DCIS but also to prognosis and choice of treatment definitely applies to high-grade, comedo-type DCIS. There is good evidence that such lesions occur frequently and will progress to infiltrating carcinoma if treated inadequately. Although we may not know as much about the natural history of low-grade DCIS, there is evidence that its clinical behaviour is less aggressive, as there is less recurrrence after excisional biopsy.4 Even less is known about the natural history of limited foci of low-grade DCIS and ADH, although we do know that women who have these lesions are at increased risk of subsequent carcinoma. Pathologists must still strive to classify these lesions to the best of our abilities, so that clinical trials can determine their biological potential and the most appropriate management.

Wayne R. Ramsay, MD
Pathologist
St. Catharines General Hospital
St. Catharines, Ont.

References

  1. Rosai J. Borderline epithelial lesions of the breast. Am J Surg Pathol 1991;15:209-21.
  2. Interobserver reproducibility in the diagnosis of ductal proliferative breast lesions using standardized criteria. Am J Surg Pathol 1992;16(12):1133-43.
  3. Consensus conference on the classification of ductal carcinoma in-situ. Cancer 1997;80(9):1798-802.
  4. Bellamy C, McDonald C, Salter DM, et al. Noninvasive ductal carcinoma of the breast: the relevance of histologic categorization. Hum Pathol 1993;24:16-23.

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