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

BACKGROUND: Although considered a favorable subtype, pure mucinous breast cancer (PMBC) can recur, and evidence for adjuvant therapy is limited. We aimed to compare outcomes of nonmetastatic PMBC with invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC) to address these uncertainties. METHODS: Individual patient-level data from 6 centers on stage I-III hormone receptor-positive and HER2-negative PMBC, IDC, and ILC were used to analyze recurrence-free interval (RFI), recurrence-free survival (RFS), and overall survival (OS), and to identify prognostic factors for PMBC. RESULTS: Data from 20,684 IDC cases, 1,475 ILC cases, and 943 PMBC cases were used. Median follow-up was 6.6 years. Five-year RFI, RFS, and OS for PMBC were 96.1%, 94.9%, and 98.1%, respectively. On multivariable Cox regression, PMBC demonstrated superior 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) compared with IDC. ILC showed comparable outcomes to IDC. Fewer than half (48.7%) of recurrences in PMBC were distant, which was a lower rate than for IDC (67.3%) and ILC (80.6%). In contrast to RFI, RFS events were driven more by non-breast cancer deaths in older patients. Significant prognostic factors for RFI among 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. A separate SEER database analysis also did not find any association of improved survival with adjuvant chemotherapy in these subgroups. CONCLUSIONS: Compared with IDC, PMBC demonstrated superior RFI, RFS, and OS. Lymph node negativity, adjuvant radiotherapy, and endocrine therapy were associated with superior RFI. Adjuvant chemotherapy was not associated with better outcomes.

Comprehensive Young Age Breast Cancer registry from clinical, genomics, and patient-reported outcomes measured with 15 years follow-up: the CHARM cohort profile.

BACKGROUND: In recognition of the distinct clinical challenges and research gaps in young breast cancer (YBC) patients, we established the Comprehensive Young Age Breast Cancer (CHARM) registry to collect prospective data. METHODS: This prospective cohort included patients who were newly diagnosed with histologically confirmed breast cancer without prior treatment at the Samsung Medical Center (SMC) in April 2013. We included patients who were either 40 years old or younger at the time of diagnosis, pregnant at breast cancer diagnosis or diagnosed with breast cancer within 1 year of delivery. All data were collected using Medidata's Rave Electronic Data. Clinical data were obtained from electronic medical records. Two experienced pathologists reviewed the pathologic data. Bone mineral densitometry tests have been conducted annually. To obtain multi-omics data, tumor tissues and blood samples were prospectively collected from consenting patients in the registry during surgery. The fertility-related factor also collected collaborated with the Department of Obstetrics and Gynecology. Anti-Müllerian hormone, estradiol, follicle-stimulating hormone, and luteinizing hormone levels were measured using an additional blood sample from baseline to last follow-up. Patient-reported outcomes were assessed using mobile questionnaires. RESULTS: A total of 1868 participants were included in the SMC YBC study. The average (standard deviation) age was 35.57 (3.79) and 99.8% of the participants were premenopausal. Among them, 1062 participants completed the PRO questionnaires. CONCLUSIONS: The SMC YBC cohort serves as a comprehensive registry for YBC to optimize care and improve knowledge regarding the management of YBC.