Peritumoural vascular invasion: a major determinant of triple-negative breast cancer outcome.

PURPOSE

Triple-negative breast cancers (TNBC) have the worst outcome of all breast cancer subtypes. Nevertheless TNBC are heterogeneous in terms of pathological, biological and prognostic behaviours. We explored clinical and pathological factors correlated with outcome in this phenotype.

METHODS

We retrospectively studied clinical and pathological factors correlated with prognosis in a series of 344 early TNBC. Staining for blood (CD31) and lymphatic (Podoplanin) vascular endothelium markers was performed to best characterise peritumoural vascular invasion (PVI) in 108 cases available for pathological reviewing.

RESULTS

Univariate and multivariate analyses performed on our whole cohort underlined PVI as an independent predictive factor of distant metastasis (p=0.00012, HR=2.72 [1.63-4.52]). Standardised pathological reviewing of 101 histologically confirmed TNBC showed that PVI, observed in 41% (28% by haematoxylin and eosin staining plus 13% by immunohistochemistry), was confirmed as the first prognostic factor in TNBC, particularly in node-negative tumours. Five-year metastasis-free survival in this subset was 87.5% and 50.8% without and with PVI, respectively (p=0.003).

CONCLUSIONS

Vascular invasion diagnosis is improved by the combination of HES and IHC. Moreover it is a major prognostic feature and must take a greater part in therapeutic management of early TNBC with the possibility to adapt the adjuvant treatment according to the predicted relapse risk.