Arising from: Costa A and Zanini V (2008) Precancerous lesions of the breast. Nat Clin Pract Oncol 5: 700–704 doi:10.1038/ncponc1239

The recent review by Costa and Zanini entitled “Precancerous lesions of the breast” is a nicely written and very timely discussion of an important problem that is becoming much more frequent.1 The article clearly points out some of the paradoxes and clinical enigmas in managing these difficult lesions. We are strong advocates, however, of the ductal intraepithelial neoplasia (DIN) and lobular intraepithelial neoplasia (LIN) terminology.2,3,4,5 We believe that adoption of this terminology will help clarify some of the confusion about the underlying biology. In this regard, we would like to pose a couple of questions and raise some points that we are sure specialists in breast cancer would be interested in.

Our first question is: If these conditions are not cancer (as stated by the authors), why are they designated as cancers? The term 'cancer' has a tremendous impact on the patient and her family. Should all these women go through life thinking they have cancer for lesions that are curable, and never metastasize or kill them? The 2003 WHO consensus meeting proposed the term lobular neoplasia as the optimum term for the spectrum of lesions previously—and unfortunately still—separated by some into atypical lobular hyperplasia and lobular carcinoma in situ. We have now identified previously unrecognized subtypes of lobular intraepithelial neoplasia that have a much higher risk for progression to invasive carcinoma;6,7 nonetheless, we continue to use the term LIN and specify the subtype with a note emphasizing the need for more urgent therapy. The same situation is true for the spectrum of DIN lesions, which includes many of the atypical hyperplasias as well as the lesions referred to as ductal carcinoma in situ. The review by Costa and Zanini notes quite appropriately that these 'in situ carcinomas' are frequently over-treated by mastectomy. Is it a surprise that surgeons continue to use mastectomy or radical radiation treatments when the term 'carcinoma' is in the designation of the lesion?

Our second question is: What does the term 'precancerous' mean? Essentially all breast tissue is 'precancerous' or 'pre-neoplastic' given the fact that there is a potential for the development of breast carcinoma in most post-pubertal breast tissue—a potential that may never be realized and a risk that continuously increases with age. Are these lesions not proliferations that serve no physiologic purpose (i.e. not reversible), but display a risk (albeit of variable magnitude) for subsequent development of carcinoma? If so, then why not use the term 'intraepithelial neoplasia' of ductal, lobular or papillary types? A neoplasia may be benign, associated with a risk for progression to malignancy, or malignant. In all other body parts and organs, the term 'in situ carcinoma' has been replaced by the term 'intraepithelial neoplasia'. We have cervical intraepithelial neoplasia, vulvar intraepithelial neoplasia, prostatic intraepithelial neoplasia, pancreatic intraepithelial neoplasia, etc. Most pathologists who are using intraepithelial neoplasia for other sites would not object to the term intraepithelial neoplasia for breast lesions. Breast surgeons and oncologists who have not been exposed to this terminology and its justifications may not realize its value. These practitioners, however, follow guidelines set by societies and committees that introduce novel terms and concepts. There should not be any difficulty with the logical terminology of LIN and DIN.

In summary, the terms DCIS and LCIS should be abandoned in favor of the more logical DIN and LIN terminology. With the widespread use of screening mammography and ever improving imaging technology, these lesions are becoming increasingly common. Clearly the DIN terminology represents a paradigm shift from looking at these lesions as cancers to considering them as risk factors—albeit of variable magnitude—for the subsequent development of cancer. This approach, however, will lend itself better to understanding the underlying complexities and molecular changes that are involved. Furthermore, the intraepithelial neoplasia terminology has the advantage of avoiding the emotionally charged designation of carcinoma.