TP53-associated early breast cancer: new observations from a large cohort.

BACKGROUND A large well-annotated recent international cohort of Li-Fraumeni (LFS) patients with early-stage breast cancer (BC) was examined for shared features. METHODS This multicentre cohort study included females with a germline TP53 pathogenic or likely pathogenic variant and nonmetastatic BC diagnosed between 2002-2022. Clinical and genetic data were obtained from institutional registries and clinical charts. Descriptive statistics were utilized to summarize proportions and differences were assessed by Chi square or Wilcoxon rank sum tests. Metachronous contralateral breast cancer (CBC) risk, radiation-induced sarcoma risk, and recurrence-free survival (RFS) were analyzed by Kaplan-Meier methodology. RESULTS Among 227 females who met study criteria, the median age of first BC diagnosis was 37 years (range 21-71), 11.9% presented with bilateral synchronous BC and 18.1% had ductal carcinoma in situ (DCIS) only. In total, 166 (73.1%) underwent mastectomies including 67 bilateral mastectomies as first BC surgery. Among those with retained breast tissue, CBC rate was 25.3% at 5-years. Among 186 invasive tumors, 72.1% were stages I-II, 48.9% node-negative, and the most common subtypes were HR+/HER2- (40.9%) and HR+/HER2 + (34.4%). At a median follow-up of 69.9 months (IQR 32.6-125.9), invasive HR+/HER2- disease had the highest recurrence risk among the subtypes (5-year RFS 61.1%, p = .0012). Among those who received radiation therapy (n = 79), the 5-year radiation-induced sarcoma rate was 4.8%. CONCLUSION We observed high rates of DCIS, HR+ and HER2+ breast cancers, with a worse outcome in the HR+/HER2- luminal tumors despite appropriate treatment. Confirmation of these findings in further studies could have implications for BC care in LFS.