325P Trends of primary tumor resection in de novo metastatic breast cancer: The experience of a Mexican center

Abstract

To date, most randomized trials have shown that primary tumor resection in patients with de novo metastatic breast cancer (MBC) does not benefit survival or quality of life. Nevertheless, this procedure is still frequent in certain settings and uncertainty on whether a select subgroup could benefit from it persists. The aim of this study is to explore the trends and impact of primary tumor resection in patients with de novo MBC. Medical records of women diagnosed with de novo MBC between 2011 and 2019 in a center in Monterrey, Mexico were reviewed. Clinicopathological features were compared with Fisher’s exact tests or logistic regressions. The Kaplan-Meier method was used to calculate progression-free survival (PFS) and overall survival (OS), and associations between variables were explored with log-rank tests or Cox models. A total of 139 patients with a median age at diagnosis of 50 years (range 26-85) were included. The median follow-up was 25 months (95%CI 19-31). Overall, 44 (32%) patients underwent surgery (8 [18%] tumorectomy and 36 [82%] total mastectomy). The median time from diagnosis to surgery was 7 months (95%CI 6-8). The proportion of patients treated with surgery was 6/11 (55%) in 2011-2013, 11/46 (24%) in 2014-2016, and 27/82 (33%) in 2017-2019 (p=0.13). Notably, patients with a single metastatic site (OR 2.6; p=0.019), a <5 cm tumor (OR 3.2; p=0.041), or exposed to chemotherapy (OR 5.4; p=0.003) were more likely to undergo surgery. The 3-year PFS was not statistically different between groups (51% vs 37%, p>0.05), while OS was significantly superior in the surgical group (69% vs 42%, p<0.01). In a subgroup analysis starting from the date of surgery including ER and HER2 status, presence of visceral metastases (HR 11.56; p=0.027) was the only independent poor prognostic factor.Table: 325PSurgical groupnon-surgical grouppn (%)44 (32)95 (68)Tumor size T1-T211 (25)8 (8)0.02 T3-T433 (75)85 (89) Unknown02 (2)Lymph node involvement 0-111 (25)21 (22)0.83 >133 (75)70 (74) Unknown04 (4)Molecular subtype HR+HER2-18 (41)46 (48)0.18 HR+HER2+5 (11)16 (17) HR-HER2+6 (14)12 (13) HR-HER2-15 (34)17 (18) Unknown0 (0)4 (4)Histological grade 1-220 (45)38 (40)0.70 319 (43)44 (46) Unknown5 (11)13 (14)Use of chemotherapy Yes39 (89)59 (62)<0.01 No5 (11)36 (38)Type of metastasis Visceral14 (32)24 (25)0.06 Non-visceral16 (36)21 (22) Both14 (32)50 (53)Number of metastatic sites 128 (64)37 (39)<0.01 >115 (34)57 (60) Unknown1 (2)1 (1) Open table in a new tab Primary tumor resection in de novo MBC is frequent in our setting. Thus, it is important to have clear guidelines to avoid unnecessary interventions and optimize resource use.