Signet ring cell breast carcinoma (SRCBC) is a rare variant of invasive lobular carcinoma and there are no large series characterizing its long-term prognosis.
The NCDB was queried from 2004-2016 to identify SRCBC patients. Patients were excluded if they had non-invasive tumors, multiple malignancies, or incomplete surgical data. Univariate analysis was performed utilizing chi-squared and Fischer’s Exact tests. Kaplan-Meier and Cox proportional hazard models were used for survival analysis.
324 patients met inclusion criteria. Patients were mostly White (75.3%), ≥50 years of age (88.2%), female (98.5%), and had a low Charlson-Deyo score (82.7%). 34.5% had Stage IV disease and 78.1% had ER+ tumors. In patients with non-Stage IV disease, 91.5% received surgery: 49.5% had lumpectomy and 50.5% underwent mastectomy. Radiation therapy was used in 40.7% (71.4% with lumpectomy and 35.8% with mastectomy) and 50% received chemotherapy. Significant differences in unadjusted overall survival were seen at 5 and 10 years based on stage (P < 0.001). On multivariate analysis, ER+ patients showed an improved survival (HR 0.5, P < 0.01) but there was no difference in survival if ER+ patients received endocrine therapy (ET) (HR 0.9, P = 0.57). Non-metastatic patients who underwent surgery had improved overall survival compared to those that did not (HR 0.5, P = 0.02), but there was no survival difference based upon type of breast operation (P = 0.8).
SRCBC frequently presents at an advanced stage. While ER+ patients appear to have improved survival, there was no clear survival benefit to receiving ET in ER+ patients.

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