Better Survival Seen With Pure Mucinous Breast Cancer

TOPLINE:

Patients with pure mucinous breast cancer (PMBC) show superior recurrence-free interval (RFI), recurrence-free survival (RFS), and overall survival (OS) compared with patients with invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC). Patients with PMBC had a 5-year RFI of 96.1%, RFS of 94.9%, and OS of 98.1%.

METHODOLOGY:

• Researchers analyzed data from 23,102 women diagnosed with hormone receptor–positive HER2-negative stage I-III breast cancer, including 20,684 with IDC, 1475 with ILC, and 943 with PMBC.
• The multicenter cohort study included patients who underwent primary breast surgery at six academic institutions in Singapore, Taiwan, Korea, and Japan between January 2000 and December 2015.
• Current National Comprehensive Cancer Network Clinical Practice Guidelines “recommend consideration of adjuvant chemotherapy only for node-positive tumors,” whereas adjuvant endocrine therapy is recommended for estrogen receptor–positive and/or progesterone receptor–positive, node-positive tumors or tumors ≥ 3 cm. Previous studies have reported no significant association between adjuvant chemotherapy and breast cancer–specific survival or OS in patients with early-stage mucinous breast carcinoma.
• The study aimed to compare the recurrence and survival outcomes of PMBC against IDC and ILC, identify clinicopathologic prognostic factors of PMBC, and explore the association of adjuvant systemic therapy with outcomes across subgroups of PMBC.
• Extracted information included patient demographics, tumor characteristics, treatment administered, and staging according to the AJCC TNM classifications.

TAKEAWAY:

• Patients with PMBC had better RFI (hazard ratio [HR], 0.59; 95% CI, 0.43-0.80), RFS (HR, 0.70; 95% CI, 0.56-0.89), and OS (HR, 0.71; 95% CI, 0.53-0.96) than patients with IDC in multivariable Cox regression analyses.
• Fewer than half (48.7%) of the recurrences in patients with PMBC were distant, which was a lower rate than for patients with IDC (67.3%) and ILC (80.6%).
• Significant prognostic factors for RFI in PMBC included positive lymph node(s) (HR, 2.42; 95% CI, 1.08-5.40), radiotherapy (HR, 0.44; 95% CI, 0.23-0.85), and endocrine therapy (HR, 0.25; 95% CI, 0.09-0.70).
• No differential chemotherapy associations with outcomes were detected across PMBC subgroups by nodal stage, tumor size, and age.

IN PRACTICE:

“This international multicenter cohort study on PMBC evaluated one of the largest contemporary real-world datasets for clinical prognostic factors, which also includes valuable data on relapse events, associations of adjuvant systemic therapy, and a comparison with the SEER database,” wrote the authors of the study. “In our cohort, as anticipated, PMBC showed superior RFI, RFS, and OS compared with IDC and ILC, which both had comparatively similar survival outcomes.”

SOURCE:

The study was led by Yoon-Sim Yap, MBBS, PhD, of the National Cancer Centre Singapore in Singapore. It was published online on May 14 in the Journal of the National Comprehensive Cancer Network.

LIMITATIONS:

The retrospective nature over a long period and lack of a central pathology review in this study are among its limitations. The high extent of missing values for tumor grade in PMBC in the multicenter cohort could impact the identified prognostic factors. The study’s findings may not be generalizable to all populations due to the specific geographic locations of the participating institutions.

DISCLOSURES:

Study author Yeon Hee Park, MD, PhD, disclosed serving on a data safety monitoring board and on an advisory board for AstraZeneca, Pfizer, Roche, Menarini, Novartis, and Daiichi Sankyo and serving as a consultant for AstraZeneca, Pfizer, Eli Lilly and Company, Gilead Sciences, Merck & Co., Inc., Eisai, Roche, Daiichi Sankyo, Menarini, Everest Pharmaceuticals, and Novartis. Additional disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.