Brain metastases developed in a woman with high-grade serous ovarian cancer despite prolonged systemic disease stability and normal CA-125 levels, highlighting the diagnostic challenges of detecting late central nervous system (CNS) relapse.
The case, published in Radiology Case Reports, describes a 55-year-old woman who was initially diagnosed in 2023 with metastatic high-grade serous ovarian carcinoma. At diagnosis, she had diffuse peritoneal carcinomatosis along with pulmonary and lymph node metastases, while her CA-125 level was markedly elevated at 1,404 U/mL.
Response to initial treatment
The patient received six cycles of paclitaxel and carboplatin combined with bevacizumab, beginning in October 2023. Treatment produced a significant clinical, radiological and biological response, including regression of peritoneal lesions and a fall in CA-125 from 1,404 U/mL to less than 4 U/mL.
Although cytoreductive surgery was proposed, the patient declined surgery as well as further systemic treatment. She was subsequently monitored using thoraco-abdomino-pelvic CT scans and serial CA-125 measurements. The disease remained clinically, radiologically and biologically stable for 19 months.
Neurological symptoms revealed brain metastases
In November 2025, the patient developed gait disturbance and was found to have right-sided hemiparesis, hyperreflexia and a positive Babinski sign.
Contrast-enhanced CT of the brain identified two large solid-cystic metastatic lesions. The largest was located in the left temporoparietal region and measured approximately 53 × 54 × 61 mm, while another lesion in the right cerebellar hemisphere measured 21 × 22 × 16 mm. Extensive surrounding edema produced significant mass effect and subfalcine herniation.
Importantly, subsequent contrast-enhanced MRI detected two additional small metastatic lesions in the right parietal and right temporal lobes that had not been visible on CT. The authors therefore emphasize the greater sensitivity of MRI for detecting small brain metastases.
CA-125 remained normal despite CNS progression
One of the notable features of the case was that the intracranial progression occurred while the patient's extracranial disease remained stable and her CA-125 level was normal.
The researchers note that CA-125 cannot reliably exclude intracranial progression, meaning that neurological symptoms should not be dismissed simply because tumor-marker monitoring remains reassuring.
Brain metastases from epithelial ovarian cancer are uncommon, with reported incidence of approximately 1%–3%. They are particularly associated with advanced-stage and high-grade serous ovarian carcinoma. The authors suggest that longer survival achieved with modern systemic treatments may allow rare metastatic sites such as the CNS to emerge later in the disease course.
Whole-brain radiotherapy improved neurological symptoms
The patient was initially treated with corticosteroids, followed by whole-brain radiotherapy (WBRT) beginning December 1, 2025. Treatment was well tolerated and resulted in significant neurological improvement. Her WHO performance status improved from 2 to 1, with regression of the right-sided pyramidal syndrome.
Five months after radiotherapy, follow-up contrast-enhanced CT showed complete resolution of the right cerebellar metastasis, while the dominant left temporoparietal lesion remained stable. The reduction in mass effect was accompanied by sustained neurological improvement and recovery of motor function.
MRI important when neurological symptoms appear
The authors point out that contrast-enhanced MRI remains the gold-standard imaging modality for detecting brain metastases and is more sensitive than CT for identifying small lesions and assessing edema and mass effect.
Management of ovarian cancer brain metastases is individualized according to factors including the patient's performance status, number and size of lesions and control of extracranial disease. Treatment options can include surgery, stereotactic radiosurgery, whole-brain radiotherapy, systemic therapy or combinations of these approaches.
The case highlights that brain metastases can occur even when ovarian cancer outside the brain appears controlled and CA-125 remains normal. The researchers recommend prompt neuroimaging when patients with ovarian cancer develop new neurological symptoms, rather than relying solely on biological monitoring.
Source: Radiology Case Reports, 2026; 21:5642–5647. DOI: 10.1016/j.radcr.2026.07.104.
