Breast cancer returned in the stomach and peritoneum after three years in remission

What happened, in summary

A 69-year-old woman had been in remission for three years after treatment for stage IIB left breast cancer. The original tumor was estrogen receptor 95% positive, progesterone receptor 5% positive, HER2-negative, and Nottingham grade 2. She had received four cycles of neoadjuvant docetaxel and cyclophosphamide with pegfilgrastim, followed by mastectomy, radiation therapy, and adjuvant anastrozole. She later came to the hospital with two weeks of upper abdominal pain, black stools, fatigue, and early satiety. Imaging showed marked thickening of the stomach wall and ascites. Initial endoscopy and ultrasound-guided biopsy showed gastritis but no malignancy. Because the clinical concern remained high, surgeons performed a diagnostic laparoscopy with wedge biopsy of the stomach and a peritoneal biopsy. Both sites contained metastatic invasive lobular carcinoma from the breast. The recurrent tumor was ER 80% positive, PR 1% positive, HER2-negative, and GATA3-positive. The oncology team discussed systemic treatment with letrozole and palbociclib, but the patient decided not to start it. After discussing the options with her family, she chose palliative care and was discharged to an inpatient hospice facility. She died a few weeks later.