Functional outcomes and complications following radiation therapy for prostate cancer: a critical analysis of the literature

Abstract

Context: Prostate cancer (PCa) patients have many options within the realms of surgery or radiation therapy (RT). Technical advancements in RT planning and delivery have yielded different approaches, such as external beam, brachytherapy, and newer approaches such as image-guided tomotherapy or volumetric-modulated arc therapy. The selection of the optimal RT treatment for the individual is still a point of discussion, and the debate centres on two important outcomes-namely, cancer control and reduction of side-effects.

Objective: To critically review and summarise the available literature on functional outcomes and rectal sequelae following RT for PCa treatment.

Evidence acquisition: A review of the literature published between 1999 and 2010 was performed using Medline and Scopus search. Relevant reports were identified using the terms prostate cancer, radiotherapy, functional outcomes, external beam radiation, brachytherapy, IMRT, quality of life, and tomotherapy and were critically reviewed and summarised.

Evidence synthesis: Related to nonuniform definition of their assessed functional end points and uneven standards of reporting, only a minority of series retrieved could be selected for analyses. Moreover, patterns of patient selection for different types of RT, inherent differences in the RT modalities, and the presence or absence of hormonal treatment also limit the ability to synthesise results from different publications or perform meta-analyses across the different treatment types. Nonetheless, several studies agree that recent technical improvements in the field of RT planning and delivery enable the administration of higher doses with equal or less toxicity. Regardless of the type of RT, the most frequently considered functional end points in the published analyses are gastrointestinal (GI) complications and rectal bleeding. Established risk factors for acute or late toxicities after RT include advanced age, larger rectal volume, a history of prior abdominal surgery, the concomitant use of androgen deprivation, preexisting diabetes mellitus, haemorrhoids, and inflammatory bowel disease (IBD). Similarly, mild acute irritative urinary symptoms are reported in several studies, whereas total urinary incontinence and other severe urinary symptoms are rare. Pretreatment genitourinary complaints, prior transurethral resection of the prostate (TURP), and the presence of acute genitourinary toxicity are suggested as contributing to long-term urinary morbidity. Erectile dysfunction (ED) is not an immediate side-effect of RT, and the occurrence of spontaneous erections before treatment is the best predictor for preserving erections sufficient for intercourse. In addition, the use of magnetic resonance imaging (MRI) permits a reduction in the dose delivered to vascular structures critical for erectile function.

Conclusions: In the future, further improvement in RT planning and delivery will decrease side-effects and permit administration of higher doses. Related to the anatomy of the prostate, these higher doses may favour rectal sparing while not readily sparing the urethra and bladder neck. As a consequence, there may be a future shift from dose-limiting long-term rectal morbidity towards long-term urinary morbidity. In the absence of prospective randomised trials comparing different types of surgical and RT-based treatments in PCa, the introduction of validated tools for reporting functional and clinical outcomes is crucial for evaluating and identifying each individual's best treatment choice.