374P - Prognostic value of histological growth pattern in patients operated for breast cancer liver metastases

Abstract

BackgroundSurgery for breast cancer liver metastases (BCLM) remains controversial. Recently, histological growth pattern (HGP), defined as replacement (rHGP) or desmoplastic (dHGP), has been demonstrated of prognostic value in patients operated for colorectal liver metastases. In BCLM, the types of HGP and their prognostic values have not been determined. We aimed to characterize HGPs in a series of patients undergoing liver resection for BCLM and correlate these patterns with postoperative outcomes. MethodsA series of 74 patients operated for BCLM was reviewed. Clinicopathologic variables, overall and disease-free survivals (OS and DFS) were analyzed. HGP could not be evaluated in 37 cases, due to exclusive radiofrequency treatment (N=22), complete pathological response (N=9) or unavailability of tissue sections (N=6). HGP was assessed in archival H&E stained tissue sections, according to international consensus guidelines in 37 patients. The proportions of rHGP and dHGP were determined in each metastasis. Patients were categorized as pure (100% rHGP or dHGP) or dominant phenotype (>50% rHGP or dHGP, on the entire tumor/normal liver interface). In case of multiple metastases, mean HGP was calculated. All these factors were correlated with OS and DFS. ResultsAfter a mean postoperative 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. Among the 37 patients analyzed for HGP, 17 were pure rHGP (46%), 10 dominant rHGP (27%), 9 dominant dHGP (24.3%) and 1 pure dHGP. Five-years OS and DFS were significantly reduced in patients with pure rHGP, respectively of 20.3 and 0% (all patients recurring within 2 years) as compared with patients with any dHGP component, respectively of 63 and 45% (p=0.03 and <0.003). No other parameter (patient, primary tumor and BCLM characteristics) was significantly different between the patients with pure rHGP and those with any dHGP component. ConclusionsIn this series of patients undergoing surgical resection for BCLM, the large majority of metastases displayed pure or dominant rHGP. Pure rHGP appears as a strong negative prognostic factor for postoperative outcome in these patients. Legal entity responsible for the studyVincent Donckier. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.