Abstract P3-07-31: Case series of 21 patients with metastastic lobular breast carcinoma to the gastrointestinal tract
Authors: Switzer Noah J , Lim Andrew , Du Lillian , Tonkin Katia , Schiller Dan 
Published: May 2015

Abstract
Background: Invasive lobular carcinoma comprises 5-15% of all breast cancer cases, with its incidence gradually increasing. While it is uncommon for breast cancer to metastasize to the gastrointestinal tract, lobular carcinoma has a disproportionately higher incidence of spread to the gastrointestinal (GI) system in comparison to other types of breast cancer. To date, most studies of gastrointestinal metastatic lobular carcinoma have been case reports and small case series.
Aim: This study is a review of all cases of lobular breast cancer with gastrointestinal metastases seen at a University affiliated Tertiary Cancer Institute over a five-year period, examining demographic, epidemiological, medical, and treatment factors that may have an association with the risk of GI metastases.
Methods: This is a retrospective chart review of all patients seen at the Cross Cancer Institute in Edmonton, Alberta, Canada between 2005-2010, with lobular breast cancer spread to the gastrointestinal tract. The outcomes of interest were: age at diagnosis, receptor status, site of primary breast cancer, stage at initial presentation, pathology, hormone receptor status, site of gastrointestinal metastasis, time from diagnosis of breast primary to gastrointestinal metastasis, time from diagnosis to death, time to gastrointestinal metastasis to death, and treatment regimen for both primary and metastatic disease.
Results: 343 consecutive cases of lobular breast cancer were reviewed, and 21(6%) were found to have GI metastases. The mean age at initial diagnosis of primary tumor was 63 years. The site of primary breast cancer was most commonly in the outer upper quadrant. Stage at presentation of the breast primary was: Stage 1A = 17%, Stage 1B/2A = 17%, Stage 2B = 22%, Stage 3A = 11%, Stage 3B = 6%, Stage 3C = 17%, and Stage 4 = 11%. Receptor status of the primary breast cancer was as follows: HER2+ = 5%, PR+ = 76%, ER+ = 90%.
The mean age at time of diagnosis of metastatic disease was 67 years. The main presenting symptoms of GI metastatic disease were:: small bowel obstruction (12.5%), incidental finding on endoscopy (12.5%), and incidental finding on imaging (12.5%). Sites of gastrointestinal spread included the stomach (52%), peritoneum (14%), duodenum (4%), jejunum (4%), transverse colon (4%), and pancreas (4%). Five-year survival from initial diagnosis of lobular breast cancer averaged 46%. Five-year survival from diagnosis of gastrointestinal metastasis was 29%.
Conclusions: Approximately 1 in 20 patients diagnosed with a primary breast cancer of lobular pathology will have metastatic spread to the GI tract, presenting approximately 4 years after their initial primary diagnosis. The most common presentation of metastatic disease is small bowel obstruction, with the most common site of spread being the stomach. There remains a paucity of data in the literature and our project is one of the first to further characterize these patients. Future research is needed in developing treatment regimens for these patients, as the 5-year survival is only approximately 1 in 4.
Citation Format: Noah J Switzer, Andrew Lim, Lillian Du, Katia Tonkin, Dan Schiller. Case series of 21 patients with metastastic lobular breast carcinoma to the gastrointestinal tract [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-31.