Supplementary Material for: BRCA1-mutant ovarian cancer with an unusual presentation of leptomeningeal disease early in the course of treatment: a case report

Introduction
Leptomeningeal disease is a rare and devastating complication of ovarian cancer which typically occurs in patients with advanced relapsed disease. It is challenging to treat and associated with a very poor prognosis.

Case Presentation
A 48-year-old patient with BRCA1-mutant high grade serous ovarian cancer underwent neoadjuvant chemotherapy followed by hysterectomy, bilateral salpingo-oophorectomy and omentectomy. There was no macroscopic residual disease after surgery and CA125 normalised.
Back pain was reported post-operatively, and at three months post-surgery, the patient presented with worsening headaches, vomiting, and photophobia. After extensive investigations including imaging which was initially reported as normal, and multiple lumbar punctures with no malignant cells detected, she was diagnosed with leptomeningeal disease.
A trial of the PARP inhibitor niraparib was initiated, but the patient deteriorated rapidly and died six weeks after presenting with headache.

Conclusion
The development of leptomeningeal disease in an ovarian cancer patient early in her treatment pathway with apparent good response to systemic therapy is exceedingly unusual. This case posed challenges both in diagnosis and in management, with limited evidence available to guide choice of therapy. Unfortunately, the response to PARP inhibitor in this patient could not be assessed due to her rapid deterioration.