Rare case of ER positive colorectal stricture demonstrating improvement with letrozole

The authors present a rare case of a patient with an estrogen receptor (ER) positive malignant colorectal stricture, with no identifiable primary breast carcinoma. There was demonstrated endoscopic and symptomatic improvement after treatment with letrozole. Gastrointestinal metastases from breast cancer usually present with a previous history of breast cancer, however our patient had no prior or current proven history of breast cancer. Biopsy and immunohistochemical staining of the malignant colonic lesion showed an adenocarcinoma with positive ER staining. Mammogram, breast ultrasound and MRI of the breasts were all negative. She was successfully treated with letrozole for 3 years that resulted in endoscopic and symptomatic improvement in her colorectal stricture.