Stage IV ER/PR-positive breast cancer with retinal vein and artery occlusion during endocrine-targeted therapy

What happened, in summary

This 56-year-old woman had a history of left breast cancer diagnosed in 2016. The tumor was a 16 mm, grade 2 infiltrating ductal carcinoma with ER 70%, PR 100%, HER2 score 1+ / negative status, and Ki-67 of 10%. There were no metastases at the beginning. She underwent left breast surgery followed by adjuvant radiotherapy to 50 Gy and tamoxifen 20 mg daily. In 2019, after menopause, endocrine therapy was switched to exemestane, then changed back to tamoxifen because of spotting. A scheduled PET/CT in 2020 showed hypermetabolic bone metastases involving the cranial vault, right first rib, sternum, multiple thoracic vertebrae, and pelvis. Tamoxifen was stopped, and systemic therapy changed to an LHR agonist plus letrozole and abemaciclib, with monthly IV zoledronic acid. Additional radiotherapy was delivered to active bone foci when needed over the next 2 years. In October 2023, she developed sudden worsening vision in the left eye. She had already been diagnosed elsewhere with central retinal vein occlusion and had received 3 ranibizumab injections and 3 sessions of scatter laser photocoagulation. In March 2024, examination showed severe chronic central retinal vein occlusion with macular edema and findings suggesting concurrent central retinal artery occlusion or ischemic injury. Because retinal structure was badly damaged, no further anti-VEGF injection was given; she received subconjunctival triamcinolone and was referred for stroke-unit evaluation. As of November 2025, she remained in ongoing metastatic breast cancer care while managing serious vision loss. Ongoing care required coordination between oncology, ophthalmology, and emergency stroke evaluation because both metastatic cancer and endocrine treatments can contribute to vascular risk and threaten vision.