Organ preservation for muscle-invasive bladder cancer (MIBC) may use trimodality therapy. This includes transurethral resection followed by radiation therapy. Radiosensitization has become one of the standard of care approaches for MIBC with high rates of local disease control and overall survival. The goal of organ preservation is to treat MIBC while preserving a well-functioning natural bladder. Debate remains over the best way to optimize radiation therapy in bladder cancer. In MIBC the role of partial cystectomy has been utilized in smaller solitary tumors with adequate local control and good urinary function. As radiation therapy techniques improve and modernize, smaller radiation volumes to a partial bladder may play an increasing role as we utilize imaging techniques coupled with adaptive radiation therapy planning and other techniques such as brachytherapy. In this review, we explore the use of brachytherapy and partial bladder fields of external beam radiation therapy in the treatment of MIBC.

Brachytherapy (BT)-based radiotherapy is one of the alternative bladder-sparing treatment modalities, which has been offered to patients with MIBC for decades. Since the first patient was successfully treated in the Memorial Hospital, NY in 19152 the treatment continued to evolve and develop. Consecutive technological developments have led to the evolution of high dose rate and image-guided BT. In collaboration with urologists, robot-assisted laparoscopic implantation techniques have improved

External beam radiation therapy traditionally has been indicated as a treatment option in MIBC. It has been controversial as to the size of the radiation field needed for treatment as radiation therapy techniques in cancer have continued to be more focused on target localization of the primary cancer and less on treatment of the entire organ such as the bladder. The evolution of treatment of partial bladder with external beam has been explored in past and current studies.

One randomized trial

The combination of TURB, EBRT and BT is more than 100 years old and a well-recognized treatment in solitary bladder cancer.37 The use of smaller fields with external beam radiation therapy or the use HDR brachytherapy (in highly selected small localized T2 tumors) has similar outcomes in terms of local control and patient toxicity. The utilization of smaller partial bladder fields with adaptive planning techniques may allow for better targeting of the tumor with decrease in adverse effects.

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