Angiogenesis sustains tumor dormancy in patients with breast cancer treated with adjuvant chemotherapy

Experimental studies performed in Folkman laboratories suggest that angiogenesis is involved in the biology of tumor dormancy. We determined the vascular index in a series of 190 women operated of node-positive invasive breast cancer treated with adjuvant chemotherapy (CMF schedule) and we studied the relationship between vascularity of primary tumors with the behaviour in time of metastasis. The study of the hazard function of recurrence (in any site) was performed resorting to a generalized linear modelling approach with a binominal error according to Efron. A total of 80 cases developed recurrences during the period of observation. We found that the hazard function of metastasis in time presented two peaks of incidence at 20 and 60 months, respectively. We also plotted the curves of the hazard function by considering three values of microvessel counts corresponding to the quartiles of their distribution. The risk of first recurrence was associated with vascular index, and the patients of the third quartile of distribution of microvessels had the highest risk. In the final full model for the risk of recurrence at 5 years vascular index provided the highest prognostic contribution followed by the number of involved axillary lymph nodes. The observation that the patients with highly angiogenic tumors are at high risk of recurrence coupled with the identification of the second peak of incidence after 5 years which was also mainly sustained by angiogenic tumors suggest that a fraction of breast cancers promote metastasis after a period of tumor dormancy. The clinical and therapeutic implications of our results are discussed.