Patient A, a 71-year-old female, with no significant comorbidities or family history, was diagnosed in January 2014 with invasive ductal carcinoma of the left breast and underwent a left modified radical mastectomy (pTxN1M0). Immunohistochemistry (IHC) showed ER (-), PR (-), HER2 (2+, FISH-), and Ki-67 (30%+). She received postoperative epirubicin–cyclophosphamide followed by docetaxel (EC-T) chemotherapy and switched to capecitabine in May 2016 after recurrence with liver and bone metastases. In May 2018, she developed decreased vision, diplopia, and swelling of the left eye, and an ocular computed tomography (CT) suggested left orbital metastasis of BC. After the patient was switched to nanoparticle albumin-bound-paclitaxel (Nab-p) for four cycles of treatment, the ocular discomfort improved, and the lesion shrank slightly. However, the patient died three months later due to systemic complications including anemia, hypoproteinemia, infection, and cancer pain (Figure 1).

The patient initially presented with ocular symptoms, subsequently confirmed as OM on imaging. Although systemic Nab-p achieved transient symptom relief, disease progression with severe complications led to death, with an OS of 55 months and an OM-specific survival of only 3 months. Local ocular therapy was withheld due to poor performance status and extensive systemic involvement. This case illustrates that in heavily pretreated advanced breast cancer, OM may indicate rapid deterioration and a limited therapeutic window. Moreover, visual disturbances in such patients should not be attributed solely to chemotherapy-related neurotoxicity, and OM should be carefully considered.

Patient B, a 41-year-old female without relevant comorbidities or family history, presented in March 2019 with blurred and distorted vision in the left eye. Positron emission tomography–computed tomography (PET-CT) revealed right BC with right axillary lymph node and bone metastases, as well as left choroidal metastasis. Biopsy confirmed invasive ductal carcinoma of the right breast (cT2N1M1, stage IV) with IHC showing ER (90%+), PR (80%+), HER2 (1+), and Ki-67 (50%+). She initially received docetaxel with zoledronic acid during which hepatic metastases developed while the ocular lesion remained stable. Subsequent treatment with letrozole plus ovarian function suppression (OFS) led to shrinkage of the choroidal lesion and relief of ocular symptoms. In April 2020, new orbital metastasis appeared in the left eye and the patient declined further treatment (Figure 2).

This case illustrates that ocular metastasis may present as an initial manifestation of BC and warrants clinical attention. The patient achieved a PFS of approximately 11 months for the choroidal metastasis and an OS of at least 13 months after diagnosis of BC with OM. Local ocular therapy was not considered because systemic endocrine therapy effectively controlled ocular symptoms. However, ipsilateral orbital metastases emerged despite well-controlled choroidal lesions, suggesting that OM at different anatomical sites may exhibit varying sensitivities to oncological treatments due to tumor heterogeneity.

Patient C, a 46-year-old female with no significant comorbidities or family history, was diagnosed in September 2018 with right BC involving axillary lymph nodes and bone metastases (cT2N2M1, stage IV). IHC revealed ER (90%+), PR (1%+), HER2 (2+, FISH-), and Ki-67 (15%+). She initially received four cycles of docetaxel plus capecitabine followed by capecitabine maintenance therapy. In November 2019, the patient was switched to letrozole + OFS combined with capecitabine after progressive disease (PD). In February 2022, she presented with new bilateral lung metastases and hepatic metastases and was switched to fluvastatin + everolimus, eribulin, trastuzumab deruxtecan (T-Dxd), and Nab-p. In December 2023, she presented with bilateral choroidal metastases, severe in the left eye with vision loss and an exophytic mass, accompanied by newly detected brain metastases. Treatment with sacituzumab govitecan (SG) stabilized ocular lesions, though central nervous system (CNS) disease progressed (Figure 3).

Unlike typical presentations, this patient’s OM manifested as an exophytic mass with atypical morphology. Rapid tumor growth within the restricted intraocular space led to early vision loss, necessitating prompt intervention. This case underscores the importance of early detection and demonstrates that timely treatment modification can effectively control ocular symptoms. Moreover, Patient C developed brain metastases shortly after OM diagnosis, suggesting a potential association between the biological behavior of OM and subsequent brain metastases.

BC-OM symptoms include proptosis, restricted eye movement, diplopia, eyelid swelling, vision loss, conjunctival congestion, blurred vision, eye pain, and eye invagination. Some patients present with a palpable eyelid mass (11), but most seek medical attention following sudden vision loss. Rapid progression can result in near-total vision loss, whereas 7% remain initially asymptomatic (12).

Clinical manifestations vary with metastatic site. Choroidal metastases, often involving the macula, typically cause rapid visual decline due to macular damage, subretinal fluid, retinal detachment, or hyperopia, enabling early detection (13). In this study, all three choroidal metastasis cases presented with blurred vision, consistent with previous reports. Orbital metastases commonly induce ocular pain and periorbital masses due to tumor traction, leading to globe invagination or motility restriction (14). Ocular pain may arise from inflammation, tumor necrosis, glaucoma, scleral involvement, or ciliary nerve compression (15, 16). One patient in this study with orbital metastasis reported ocular pain, in line with the literature. Conjunctival and optic nerve canal metastases may manifest as painless conjunctival masses or progressive vision loss (17, 18). Involvement of extraocular muscles or the oculomotor nerve can result in strabismus, paralysis, or restricted movement.

BC-OM is typically unilateral but may progress to bilateral, multifocal involvement alongside systemic metastases in later stages (3, 19, 20). While some BC cases are initially identified due to OM symptoms, most OM cases occur secondary to visceral, bone, or CNS metastases. In this study, one of three patients (33.3%) presented with OM as the initial diagnosis, consistent with previous reports. Asymptomatic choroidal metastases occur in 5% of metastatic BC cases, increasing to 11% in multiorgan metastases, with 67% of detected alongside involvement of other organs (21), suggesting that multiorgan metastasis as a high-risk factor for OM.

Brain metastases occur in approximately 6% of BC cases but rise to 60% among patients with OM (4). Kuhn et al. proposed that cancer cells metastasize to the choroid and spread to the brain via the optic nerve after interacting with pigmented cells (22). Choroidal metastases more frequently lead to brain involvement than orbital metastases, potentially worsening prognosis. Timely cranial CT or MRI upon BC-OM diagnosis is recommended for early detection, optimized treatment, and improved outcomes. In this study, patient C developed brain (meningeal) metastases shortly after or concurrently with OM, consistent with literature findings.

Asymptomatic or mildly symptomatic OM patients often neglect regular eye examinations, resulting in missed or delayed diagnoses. Early detection and intervention are essential for preserving visual function and improving QoL. BC-OM diagnosis requires integrating patient history, clinical signs, and auxiliary tests, including ophthalmic imaging, general imaging, and pathological biopsy. Ocular ultrasound serves as an initial screening tool, while biopsy remains the gold standard but requires strict indications. Comprehensive evaluation supports accurate diagnosis, lesion localization, and treatment planning.

Ocular metastatic cancer typically occurs in advanced malignancies with systemic, multiorgan involvement, making curative surgery impractical. Treatment primarily focuses on symptom relief. Since metastatic lesions share biological characteristics with the primary tumor, standardized systemic therapy can help control ocular involvement (34–36). Currently, no standardized protocol exists for BC-OM, highlighting the need for multidisciplinary collaboration. Treatment decisions are guided by metastasis burden, visual function, and life expectancy. Systemic therapy remains the cornerstone of management, often supplemented by local treatments to improve survival and QoL (37).

Ocular metastatic cancer represents an advanced malignancy that often involves multiple organs. Although visual prognosis is generally favorable after treatment, systemic outcomes remain poor and vary depending on the primary tumor and type of metastasis (33). The presence of ocular metastasis further worsens prognosis, with median survival of BC patients ranging from 5 to 17 months (19). Advances in anticancer drugs and radiotherapy have improved survival and QoL in BC-OM patients, highlighting the importance of early detection, proactive treatment, and prevention of multi-organ metastasis.