Abstract PO5-20-08: A Case of Multifocal Ductal Breast Carcinoma with Extension into Lobules and Concurrent Primary Colon Adenocarcinoma

Abstract

Abstract Background Multifocal (MF) multicentric breast cancer is a form of breast cancer that consists of disease independently developing at various locations due to a tumor clone spreading within the ductal complex. Multifocal breast cancer is associated with increased local recurrence. Our case highlights an example of multifocal breast cancer and addresses treatment challenges. Case presentation The patient is a 52-year-old African American female with a history of HCV cirrhosis, diabetes mellitus, and hypertension who presented with a palpable 4 cm right breast mass, without adenopathy, clinically Stage II, T2N0. Mammogram revealed a 2.5 cm right breast mass and three right level 1 axillary nodes with biopsy confirming invasive ductal carcinoma with extension into the lobules, ER positive (3%)/PR-/HER2-, Ki-67 95%. Neoadjuvant paclitaxel, carboplatin, and pembrolizumab was initiated but she incurred complications of decompensated liver cirrhosis after the second cycle and treatment was held. After 2 cycles her tumor was not palpable, and surgery was recommended, but due to COVID infection and concurrent decompensated liver failure surgery management was delayed. She underwent staged surgery with partial mastectomy without lymph node exploration. Histopathology showed DCIS grade 3 with extension into lobules and invasive ductal carcinoma with no lymphovascular invasion and all margins were negative, pathological stage ypT3NxM0. Immunohistochemistry demonstrated partial ER+ (50%)/PR-/HER2-, Ki-67 80%. She was given 4 cycles of adjuvant cyclophosphamide, adriamycin, pembrolizumab and continued on maintenance pembrolizumab. The patient was found with anemia out of proportion to chemotherapy and underwent colonoscopy that showed a colonic mass. Biopsy showed a primary moderately differentiated colonic adenocarcinoma. Her re-excision with new margins for partial mastectomy had negative margins, and 2 negative sentinel lymph nodes for ypN0. Genetic testing was negative. She continued on adjuvant immunotherapy with pembrolizumab for breast cancer. She is planned to start on adjuvant anastrozole. Patient has completed adjuvant radiation treatment and has no new complaints. She is pending curative intent completion colectomy for colon cancer. Discussion This case of MF breast cancer is significant, as one foci was ER negative, which responded to neoadjuvant chemoimmunotherapy and other ER positive that did not respond to treatment and was surgically excised. The pathology report from the surgical specimen revealed DCIS with extension into the lobules. Due to her tenuous clinical condition, she had staged surgeries for breast cancer, and now colon cancer. Genetic testing is negative. Currently, there is insufficient data to suggest which surgical approach is preferred in MF breast cancer. Based on the literature, breast conservation therapy (BCT) is a feasible option and is oncologically safe. Due to the patients’ medical condition and infections, it was felt a less invasive surgery could offer cure and minimize complications. Our patient underwent neoadjuvant chemoimmunotherapy, followed by partial mastectomy, adjuvant chemoimmunotherapy, second staged completion breast surgery, radiation therapy, and anti-estrogen therapy. MF breast cancer is associated with increased lymph node involvement. A 2022 meta-analysis found that multifocal and multicentric breast cancer has a slightly increased risk of death as compared to unifocal tumors. Lastly, our patient is African American, and multifocal tumors occur with a higher incidence in African Americans (43.4%) and Asian patients (37%) as compared to whites (28.9%). This case of breast cancer highlights treatment challenges in a case of multifocal multicentric breast cancer occurring concurrently with a secondary primary colonic cancer. Citation Format: Rabab Jafry, Hina Khan, Jessica Jones. A Case of Multifocal Ductal Breast Carcinoma with Extension into Lobules and Concurrent Primary Colon Adenocarcinoma [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-20-08.