Efficacy of Combined Pembrolizumab and Pelvic Radiotherapy for Bladder Cancer With Rectal Metastases

Rectal metastases from urothelial carcinoma (UC) are extremely rare with poor prognosis when treated with gemcitabine and cisplatin (GC) chemotherapy, radiation therapy, and total pelvic exenteration. Long-term survival has not been observed in patients treated with GC chemotherapy, radiation therapy, or total pelvic resection. However, there have been no reports on the efficacy of pembrolizumab therapy for this specific condition. Herein, we describe a case of rectal metastasis from UC, treated with combined pembrolizumab and pelvic radiotherapy.

A 67-year-old male patient with an invasive bladder tumour underwent robot-assisted radical cystectomy and ileal conduit diversion followed by neoadjuvant GC chemotherapy. The pathological findings showed high-grade UC, pT4a, with a negative surgical margin. He presented with an impacted ileus due to severe rectal stenosis on postoperative day 35 and underwent a colostomy. Pathologically, rectal biopsy confirmed rectal metastasis; thus, the patient was started on pembrolizumab 200 mg every 3 weeks and pelvic radiotherapy with a total dose of 45 Gy. The rectal metastases remained well controlled with stable disease status, and no adverse events were observed 10 months after the initiation of combined pembrolizumab and pelvic radiotherapy.

Pembrolizumab combined with radiation therapy may be an alternative treatment for rectal metastases from UC.