Prostate Cancer and Malignant Ascites: The Mayo Clinic Experience With a Rare and Aggressive Disease Progression

• Unusual sites of prostate cancer spread have been demonstrated in several case reports; however, there exists a notable dearth of investigations regarding malignant ascites due to prostate cancer. In our study, we present a case series of 25 prostate cancer patients who presented with malignant ascites. They have been on systemic therapy in the form of androgen deprivation therapy and were classified according to their additional lines of treatment to best supportive care and chemotherapy. • We found that malignant ascites due to prostate cancer is associated with advanced metastatic castration-resistant disease with predominant visceral involvement, especially the liver, unusual sites of disease progression, and poor clinical outcomes despite standard systemic therapy. The median overall survival for the whole cohort was 4 months; in addition, the median overall survival for supportive care and chemotherapy groups was 1 and 4.5 months, respectively. Overall survival was not significantly different in patients who received chemotherapy versus supportive care. With the unmet need for better systemic therapy for malignant ascites with prostate cancer, the best supportive care to improve the quality of life for those patients is highly encouraged.