Histological Growth Pattern As A Potential Prognostic Factor In Patients Operated For Breast Cancer Liver Metastases.

e12576 Background: Indications for surgery in patients with breast cancer liver metastases (BCLM) remain ill-defined. Recently, the histological growth pattern (HGP), such as desmoplastic (dHGP), associated with angiogenesis and inflammation, or replacement (rHGP), associated with vessel co-option and in the absence of immune infiltrate, has been demonstrated as a significant prognostic factor in patients operated for colorectal liver metastases. In BCLM, the distribution and the prognostic value of HGP are poorly documented. We aimed to characterize HGP in a series of patients undergoing liver resection for BCLM and correlate these patterns with postoperative outcomes. Methods: A consecutive series of 58 patients undergoing liver resection for BCLM was reviewed. Clinicopathologic parameters of these patients were analyzed. HGPs were assessed in archival H&E stained tissue sections, according to international consensus guidelines. The proportions of rHGP and dHGP were determined in each metastasis. In case of multiple metastases, mean HGP was calculated for each patient. Patients were categorized as pure (100% rHGP or dHGP) or dominant phenotype ( > 50% rHGP or dHGP, on the entire tumor/normal liver interface). All these factors were correlated with overall and disease-free survivals (OS and DFS). Results: After a mean follow-up of 81 months, 5-years OS and DFS in global population were 49.7% and 22.7%, respectively. No clinicopathologic preoperative factor was found to be predictive for OS or DFS. HGPs were analyzed in a first set of 21 patients. All patients showed some rHGP component. Of these, 11 were pure rHGP (52.4%), 4 dominant-rHGP (19%) and 6 dominant-dHGP (28.6%). Five-years postoperative OS and DFS were of 19.4 and 18.2% in pure rHGP, as compared with 64.8 and 33.3% in patients with some dHGP component (p = 0.089). Conclusions: rHGP appears as the main phenotype of BCLM. First analyzes suggest that surgery for BCLM with pure rHGP is associated with a worse oncological outcome as compared to BCLM with a dHGP component.