Promising effects of pazopanib with radiation on an advanced prostate leiomyosarcoma after failure of systemic chemotherapy

Abstract

Other immune‐histologic stains showed positive for SMA (strong and diffuse positive), H‐caldesmon (diffuse and weakly to moderate positive), PR (focally and weakly positive); negative for CK, CAM5.2, CD34, and P63 Prostate leiomyosarcoma is an extremely rare and aggressive tends to recur as well as metastasize to liver and lung with poor outcome. [...]there is no standard treatment recommendation for the prostate leiomyosarcoma. According to PALETTE trial, the metastatic sarcoma treated with pazopanib can improve progression free survival (median progression‐free survival is 4.6 months for pazopanib compared with 1.6 months for placebo). [...]we report a rare case of prostate leiomyosarcoma with aggressive behavior of rapid progression after failure to surgical intervention and systemic chemotherapy.

Dear Editor

Prostate cancer is the second most common cancer in men worldwide. The most frequent prostate cancer is prostatic adenocarcinoma, which accounts for 90% to 95% of prostate cancer. Prostate leiomyosarcoma, nevertheless, accounts for less than 0.1% of primary prostate malignancies and is an extremely rare and highly aggressive neoplasm. Here, we present an advanced prostate leiomyosarcoma with promising effects of pazopanib and radiation after failure of systemic chemotherapy.

A 62‐year‐old‐healthy man presented with difficulty in voiding and acute urine retention intermittently in October 2016. The trans‐rectal ultrasound scan showed mild enlargement of the prostate with an estimate of 28.8 mL in prostate volume and one hypoechoic lesion in the left prostate lobe. Transurethral resection of the prostate was performed on November 4, 2016, under the clinical impression of benign prostatic hyperplasia. However, the pathologic report showed otherwise the prostate leiomyosarcoma. The MRI revealed a residual prostatic cancerous tissue for 2.4 × 2.1 × 2.4 cm in size in the left prostatic lobe on November 25, 2016. No observable evidence of bone metastasis in the bone scan. The tumor, however, progressed rapidly and the sonography showed to attain to a size of 36.6 mm of the prostate tumor on December 6, 2016; more than 50 mm on December 16, 2016, from the serial follow up. The patient received robotic assisted radical prostatectomy with bilateral pelvic lymph node dissection on January 2, 2017. The pathologic report concurred with prostate leiomyosarcoma, grade 3. However, the tumor continued to progress with local and abdominal wall metastasis rapidly 1 month after the surgery. Then he received two courses of salvage chemotherapy with doxorubicin and Ifosfamide with poor response. The PET/CT showed progressive disease with hypodense soft tissue masses along the left external iliac, peritoneum adjacent to abdominal walls after systemic chemotherapy (Figure ). The tumor seeding was then highly suspected, therefore, the treatment was shifted to pazopanib and radiotherapy on prostate tumor bed and the soft tissue masses along the left external iliac, peritoneum adjacent to abdominal walls with a dosage of 7600 cGy/38fx. After 9 months of pazopanib treatment, the follow‐up images confirmed the regression of tumor (Figure ). The biopsy was not performed after discussion with the patient.

Prostate leiomyosarcoma is an extremely rareand aggressive tends to recur as well as metastasize to liver and lung with poor outcome. Until now, there is no standard treatment recommendation for the prostate leiomyosarcoma. Multimodality treatment combinations including surgery, preoperative or postoperative radiation therapy and neoadjuvant or adjuvant chemotherapy have been used. Chemotherapy with anthracycline (doxorubicin or epirubicin)‐based combinations with alkylating agents (cyclophosphamide, ifosfamide, or dacarbazine) and/or vinca alkaloids (vinblastine or vincristine) were common regimens.

Pazopanib is a multi‐tyrosine kinase inhibitor with antiangiogenic properties. According to PALETTE trial, the metastatic sarcoma treated with pazopanib can improve progression free survival (median progression‐free survival is 4.6 months for pazopanib compared with 1.6 months for placebo). Though leiomyosarcoma accounts for 45% in all patients in the report, however, no prostate leiomyosarcoma was known.

In conclusion, we report a rare case of prostate leiomyosarcoma with aggressive behavior of rapid progression after failure to surgical intervention and systemic chemotherapy. Target therapy of pazopanib with radiation therapy showed response in this patient with regression of tumor. To our best knowledge, it is the first report of promising effect of pazopanibon prostate leiomyosarcoma. More studies are warranted for this kind of aggressive malignancy.

CONFLICT OF INTEREST

All authors declare no conflict of interest.