High-early recurrence rate in a cohort of young women with breast cancer in Mexico.
Authors: Villarreal-Garza Cynthia , Becerril Gaitan Andrea , Vaca-Cartagena Bryan , Mesa-Chavez Fernanda , Ferrigno Ana Sofia , Platas Alejandra , Miaja Melina , Fonseca Alan , Cruz-Ramos Marlid , Aguilar Dione , Labra Lucero , Bargallo Rocha Enrique , Mohar Betancourt Alejandro 
Published: June 2021

e12560 Background: Young women with breast cancer (YWBC) have worse survival outcomes compared to their older counterparts. Even though a higher recurrence rate has been previously documented in this population, there is still limited information regarding the timing, prevalence and type of disease recurrence. This study aims to describe the patterns of early recurrence in Mexican YWBC. Methods: Women aged ≤40 years at diagnosis, accrued in the Joven & Fuerte prospective cohort, with stage I-III BC and having at least a 2-year follow-up were analyzed. Recurrence-free survival (RFS) and overall survival (OS) at 2 years were evaluated using the Kaplan-Meier estimate. Log-rank and Fisher’s exact tests were employed for group comparisons; the Cox regression method was used to identify factors associated with RFS and OS. Results: A total of 210 patients with a median age at diagnosis of 36 years (range: 21-40) were analyzed. Most patients were diagnosed with stage II (50%) and III (39%). Distribution according to molecular subtype was: 50% HR+/HER2-, 26% TNBC, 17% HR+/HER2+, and 7% HR-/HER2+. In total, 31 (15%) patients experienced early disease recurrence. The two BC subtypes with the highest recurrence rate were TNBC (12/54; 22%) and HR+/HER2+ (6/35; 17%), followed by HR+/HER2- (12/106; 11%) and HR-/HER2+ (1/15; 7%). Stage at diagnosis was associated with a higher risk of recurrence (stage III: 21/82 (68%); stage II: 10/94 (32%); p= 0.003). Of the total recurrences, 23% were locorregional and the remaining 77% were distant metastases. The most common sites of distant metastases were lung (46%), bone (38%) and central nervous system (33%). Notably, 50% of distant recurrences affected multiple organs. Overall, RFS at 2 years was 85.2% (95%CI 79.7-89.4). In the univariate analysis, age ( < 35 v ≥35), type of surgery (conservative v mastectomy) and BMI ( < 25 v ≥25 kg/m²) were not significantly associated with RFS. In a multivariate model, node involvement (HR = 2.76; p= 0.044), not receiving chemotherapy (HR = 3.86; p= 0.024) and TNBC (HR = 2.47; p= 0.035) were independently associated with worse RFS. The OS found in this cohort was 92.9% (95%CI 88.4-95.6). In a multivariate model, TNBC (HR = 3.71; p= 0.029) and stage III at diagnosis (HR = 5.55; p= 0.008) were associated with worse OS. Conclusions: This cohort of YWBC experienced a low RFS at 2 years. As previously reported, patients with node involvement and TNBC faced a greater risk of early recurrence. Noteworthy, a high prevalence of distant metastases was observed, with half of them involving > 1 site. Future studies are warranted to elucidate the factors associated with early recurrence in YWBC. In addition, the incorporation of new treatment strategies is urgently needed to improve disease outcomes in this group.