Association between PIK3CA activating mutations and outcomes in early-stage invasive lobular breast carcinoma treated with adjuvant systemic therapy
PIK3CA activating mutations in invasive lobular breast carcinoma
Background and purpose:
The role of PIK3CA activating mutations on outcomes and efficacy of adjuvant endocrine therapy (ET) in patients with early-stage invasive lobular carcinoma (ILC) is unclear.
A single institution study of patients with early-stage ILC treated between 2003 and 2008 was performed. Distant metastasis-free survival (DMFS) and overall survival (OS) were collected based on PIK3CA activating mutation status in the primary tumor. An association between PIK3CA mutation status and prognosis in all patient cohort was analyzed by Kaplan-Meier survival curve, whereas an association between PIK3CA mutation and ET was analyzed in ER and/or PR- positive group of our patients by the Cox proportional hazards model.
Median age at diagnosis of all patients was 62.8 years and median follow-up time was 10.8 years. Among 365 patients, PIK3CA activating mutations were identified in 45%. PIK3CA activating mutations were not associated with differential DMFS and OS (p=0.36 and p=0.42, respectively). In patients with PIK3CA mutation, each year of tamoxifen or AI decreased the risk of death by 27% and 21% compared to no ET. The type and duration of ET did not have significant impact on DMFS, however longer duration of ET had a favourable impact on OS.
PIK3CA activating mutations are not associated with an impact on DMFS and OS in early-stage ILC. Patients with PIK3CA mutation had a statistically significantly decreased risk of death irrespective of whether they received TAM or an AI.
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Copyright (c) 2023 Domen Ribnikar, Valentina Jerič Horvat, Ivica Ratoša, Zachary W Veitch, Biljana Grčar Kuzmanov, Srdjan Novaković, Erik Langerholc, Eitan Amir, Boštjan Šeruga
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