The prognostic significance of tumor-associated stroma in invasive breast carcinoma

Fibroblasts in the stromal component of a tumor may influence tumor progression in various organs. The prognostic significance of tumor-infiltrating lymphocytes is also frequently reported. However, the prognostic significance of the stromal component in breast cancers, particularly those of high grade, has not been established. In this study, we analyzed surgically resected specimens from 545 patients with breast carcinoma, including 193 high-grade tumors, for tumor-stroma ratio, dominant stroma type [collagen (C), fibroblast (F), or lymphocyte (L) dominant type], and central fibrosis on hematoxylin-eosin-stained histological sections. We correlated these features with clinical prognosis. Among the 533 specimens examined, 127 (23.3 %) were of C type, 292 (53.6 %) of F type, and 114 (20.9 %) of L type. Central fibrosis was found in 99 tumors (18 %). The dominant stroma type was a significant prognostic factor on univariate and multivariate analyses, together with T classification, nodal status, and Bloom-Richardson grade. Tumor-stroma ratio and central fibrosis did not predict survival on multivariate analysis. Even in high-grade tumors, relapse-free intervals differed significantly according to dominant stroma type. Thus, conventional hematoxylin-eosin-stained tumor slides may contain more prognostic information than previously thought; in particular, the dominant stroma type in invasive breast cancer may potentially be used to predict outcome.