Scar cancers: pathologic findings from the National Surgical Adjuvant Breast Project (protocol no. 4) - IX.

The uncomplicated non-encapsulated sclerosing lesion (NESL) or radial scar of breast is a banal lesion which may be confused with tubular carcinoma. Yet, that the latter may arise in such scars is strongly suggested by the recognition of examples portraying morphologic features consistent with such 'early' transformation. Further, 38% of 1569 cases of unequivocal invasive breast cancers from patients enrolled in the National Surgical Adjuvant Breast Project, protocol 4, were found to be associated with scar. The scar in 14% of these was strikingly similar if not identical morphologically with the NESL or radial scar (type 1 scar cancer). Four other types of scar were identified. It is uncertain whether these represent variations of the NESL or are unique. However, each type possessed some distinguishing pathologic characteristics as disclosed by contingency table analyses of 36 histopathologic and 6 clinical features of these cancers. Most importantly, 6-year postmastectomy survival was significantly better as revealed by life-table analyses for patients whose cancers were designated as types 1 and 4 than for those with other scar types or in whom their cancer lacked scar. This relationship was found to be independent of nodal status. Ductal obliteration, a common finding in the banal NESL and scar cancers, has been previously suggested to play a role in their evolution. Our observations indicate that vascular obliterative alterations may be equally or perhaps even more significant in this regard. This as well as other features suggests an analogy between them and so-called scar cancers of the lung. Attention is directed to the prognostic significance of type and degree of tubule formation observed in some breast cancers. The results suggest a revision of the scheme utilized for the histologic grading of breast cancers. However, it appears valid to simply categorize breast cancer into well-differentiated (histologic grades 1 and 2) and poorly differentiated (histologic grade 3) types. Our data does not support the hypothesis that tubular cancer may 'progress' into less differentiated forms.