Abstract P6-07-33: A clinicopathologic analysis of 45 patients with metaplastic breast cancer
Authors: Verma S , Cimino-Mathews A , Figueroa Magalhaes MC , Zhang Z , Stearns V , Connolly RM 
Published: August 2014

Background: Metaplastic breast carcinoma (MBC) is a rare tumor, accounting for &lt; 1% of all breast cancers. The 5-year survival rate is approximately 65% vs. 89% for conventional invasive ductal cancer (IDC), therefore improved treatment options are required. Evidence as to how to manage patients with MBC is derived from a number of single institution case series, and usually follows the treatment paradigm for conventional IDC. We aimed to review the clinicopathologic features of women with MBC treated at our institution to add to the current literature, and to identify potential prognostic biomarkers of outcome.

Patients and Methods: The study was approved by the Institutional Review Board of John Hopkins University. We retrospectively identified patients &gt; 18 yrs of age with histologic confirmed diagnosis of MBC through the Johns Hopkins Pathology archives from March 1999-February 2012. We collected and reviewed data relating to clinicopathological features, local and systemic treatments, and patient outcomes. Survival probabilities at specific time points were estimated using the Kaplan-Meier method and confidence intervals (CI) obtained using the Greenwood formula.

Results: Of 45 cases identified, median age was 59 (range 38–93), 62% of patients were white and 36% were black. Histologic subtypes identified were chondroid (24%), spindle (20%), sarcomatoid (16%), squamous (11%) and mixed (29%). Median tumor size 3cm (range 1–14.8cm); lymph node status was positive (24.4%)/negative (51.2%)/unknown (24.4%); 60% had grade 3 tumors; 69% were estrogen receptor (ER)/progesterone receptor (PR)/HER2-negative (triple-negative), 20% ER/PR-positive, with 4 HER2 positive tumors and 3 HER2-unknown. Two patients had metastatic disease at diagnosis. Neoadjuvant therapy (anthracycline-taxane based in 83%) was administered in 6 patients, with one patient achieving complete pathological response to dose dense adriamycin and cyclophosphamide followed by weekly paclitaxel. All patients underwent surgery (82% negative margins) and 60% received adjuvant radiation. Adjuvant chemotherapy, predominantly anthracycline +/− taxane-based was administered in 58% cases (excluding neoadjuvant). 5 year recurrence-free survival (n = 43) was 63.3% (95% CI, 0.382–0.884) with median follow up of 26.2 months (range 1.7–137.2 months). 5 year overall survival (n = 45) was 68.7% (95% CI, 0.448–0.926) at median follow up 28 months (range 2.4–137.9 months).

Conclusion: We report one of the largest single institution case series of clinicopathologic features associated with MBC in the literature. MBC is associated with a worse prognosis than conventional IDC, despite a relatively low rate of positive nodal involvement. The majority of patients in this series had high grade, triple-negative tumors and were treated with optimal local and systemic therapy. We will report results of subgroup analyses at the time of presentation. We also aim in the future to analyze available archival tumors to identify potential prognostic and predictive biomarkers, and anticipate that these results will provide the rationale for clinical trials with novel investigational agents in this area of unmet need.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-07-33.