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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Friday, August 23, 2024
A multicenter cohort study published in the JNCCN–Journal of the National Comprehensive Cancer Network revealed superior survival outcomes in patients with nonmetastatic pure mucinous breast cancer vs invasive ductal carcinoma and invasive lobular carcinoma. According to Ryan Ying Cong Tan, MBBS, of the National Cancer Centre Singapore, and colleagues, these data continue to support a favorable classification for this rare subtype and recommendation for treatment de-escalation in the current NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®).
The study cohort comprised 23,102 patients with stage I to III hormone receptor–positive, HER2-negative invasive ductal carcinoma (89.5%), invasive lobular carcinoma (6.4%), and pure mucinous breast cancer (4.1%) who underwent primary breast surgery in Singapore, Taiwan, Korea, and Japan. Follow-up data were provided for a median of 6.6 years.
The 5-year recurrence-free interval, recurrence-free survival, and overall survival rates were 96.1%, 94.9%, and 98.1%, respectively, in patients with pure mucinous breast cancer. Based on multivariable Cox regression, those with this subtype vs invasive ductal carcinoma demonstrated superior recurrence-free interval (hazard ratio [HR] = 0.59), recurrence-free survival (HR = 0.70), and overall survival (HR = 0.71); comparable outcomes were observed between those with invasive ductal and lobular carcinomas. Patients with pure mucinous breast cancer exhibited a lower distant recurrence rate (48.7%) than those with invasive ductal carcinoma (67.3%) and invasive lobular carcinoma (80.6%).
According to the investigators, in contrast to recurrence-free interval, recurrence-free survival events in older patients were driven largely by non–breast cancer deaths. Positive lymph node(s) (HR = 2.42), radiotherapy (HR = 0.44), and endocrine therapy (HR = 0.25) seemed to be significant prognostic factors for recurrence-free interval among patients with pure mucinous breast cancer. In both the study cohort and a Surveillance, Epidemiology, and End Results Program (SEER) database cohort, adjuvant chemotherapy was not found to be associated with better outcomes across various pure mucinous breast cancer subgroups defined by nodal stage, tumor size, and age.
Disclosure: Dr. Tan reported no conflicts of interest. For full disclosures of the other study authors, visit jnccn.org.
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