Gastrointestinal Metastases From Lobular Breast Carcinoma: A Literature Review.

Invasive lobular carcinoma (ILC) represents a rare subtype of breast carcinoma, originating from the lobule. Unlike ductal carcinoma, ILC does not express E-cadherin and thus can metastasize to uncommon sites. We aimed to investigate the clinicopathological characteristics of the rare subgroup of ILC patients with gastrointestinal (GI) metastases. A PubMed search was undertaken using the terms "Lobular Breast Carcinoma" AND "Gastrointestinal Metastasis." We identified 169 cases, with metachronous GI metastatic disease being approximately twice as common as synchronous GI metastases. The median age at initial diagnosis was 56.7 years (24-88). The majority of patients were hormonal receptor-positive and only a small minority was HER2-positive. The appearance of a gastrointestinal lesion was often the mode of revelation of ILC. Differential diagnosis from primary gastrointestinal cancer is sometimes challenging, especially in the case of signet-ring cell carcinoma. The median time from breast cancer diagnosis to GI metastases was 6.5 years (0-33). Most common metastatic sites include the stomach, colon, and rectum, in order of decreasing frequency, whereas metastases were found in every part of the digestive tract. In conclusion, metastases of ILC can arise in the gastrointestinal tract and they should be managed similarly to metastatic breast cancer.