Outcomes in Nonmetastatic Hormone Receptor-Positive HER2-Negative Pure Mucinous Breast Cancer: A Multicenter Cohort...

Area of Science:

• Oncology
• Medical Research
• Clinical Trials

Background:

• Pure mucinous breast cancer (PMBC) is considered favorable but can recur.
• Evidence for adjuvant therapy in PMBC is limited.
• This study compares PMBC outcomes to invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC).

Purpose of the Study:

• To compare recurrence-free interval (RFI), recurrence-free survival (RFS), and overall survival (OS) for nonmetastatic PMBC versus IDC and ILC.
• To identify prognostic factors for PMBC recurrence and survival.

Main Methods:

• Individual patient data from 6 centers for stage I-III hormone receptor-positive, HER2-negative PMBC, IDC, and ILC were analyzed.
• Outcomes including RFI, RFS, and OS were compared using multivariable Cox regression.
• Prognostic factors for PMBC were identified.

Main Results:

• PMBC demonstrated superior RFI, RFS, and OS compared to IDC.
• Fewer PMBC recurrences were distant compared to IDC and ILC.
• Positive lymph nodes were associated with worse RFI, while radiotherapy and endocrine therapy were associated with better RFI in PMBC.

Conclusions:

• PMBC has superior RFI, RFS, and OS compared to IDC.
• Adjuvant radiotherapy and endocrine therapy are associated with improved RFI in PMBC.
• Adjuvant chemotherapy did not show an association with improved outcomes in PMBC.