**Abstract**

Chronic radiation proctitis (CRP), characterized by increased frequency and urgency of defecation, fecal incontinence and rectal bleeding, is an under-estimated cause of morbidity after pelvic irradiation for urological and gynecological malignant diseases. Despite improvements in radiotherapy technology, 90% of patients have persistent long term symptoms and 50% of all patients report impairment of quality of life after pelvic radiotherapy. Research by an Australian group of clinician scientists, including prospective, longitudinal and retrospective studies as well as a randomized trial of two current approaches used for the treatment of haemorrhagic radiation proctitis over a time span exceeding two decades, have provided important insights into the prevalence, pathophysiology natural history and treatment of CRP. The findings have important implications for the management and amelioration if not prevention of CRP. Data from 4 selected studies conducted by the Australian group, each characterizing changes in anorectal function and anal sphincteric morphology, are first presented. This is followed by discussion of how the findings have led to the development of more rational therapeutic interventions for CRP and how novel approaches designed to reduce the prevalence of CRP when combined could lead to its elimination in the foreseeable future.

**Keywords:** Pelvic cancer, radiotherapy, anorectal physiology, haemorrhagic proctitis, quality of life

## **1. Introduction**

Among the estimated 300,000 patients per year worldwide undergoing radiotherapy for pelvic malignant diseases such as carcinoma of the uterine cervix and corpus, bladder and prostate, nine out of 10 will develop a permanent change in their bowel habit [1]. Furthermore, this UK group and an Australian group of clinician scientists have independently reported that 50% of all patients report an adverse impact on activities of daily living (ADL) after pelvic radiotherapy [1, 2].

The radiation induced bowel symptoms which have the greatest adverse effect on ADL are anorectal symptoms such as increased frequency and urgency of defecation, fecal incontinence and rectal bleeding collectively referred to as Chronic Radiation Proctitis (CRP) [1–3].

The prevalence of CRP is uncertain. Studies using physician based questionnaires such as the Radiation Therapy Oncology Group (RTOG) scales report a prevalence of only 5–10% [4]. However, because these scales do not evaluate common anorectal symptoms such as urgency of defecation and fecal incontinence, physician based scales probably under-estimate the prevalence of CRP. In support of this, studies that have included patient-based questionnaires such as the Late Effect Normal Tissue – Subjective Objective Management Analytic (LENT – SOMA) scales have reported that up to 78% of patients have persistent anorectal symptoms after radiotherapy for prostate carcinoma [5–9]. Although persistent anorectal symptoms impair the daily activities of 50% of all patients 5 years after pelvic radiotherapy, the pathophysiology of anorectal dysfunction has not been fully characterized and its treatment is unsatisfactory. Previous physiological studies in patients with anorectal dysfunction after radiotherapy have been limited either by methodological inadequacies [10] or lack of follow-up studies beyond 2 years [11, 12].

The rationale for the selection of each of the 4 listed studies for discussion in this chapter are provided under the sub-headings below:

1.Pathophysiology and natural history of anorectal sequelae following radiation therapy for carcinoma of the prostate [2]

In view of the limitations of previous physiological studies of anorectal function after radiotherapy for prostate carcinoma, 5 year data from an Australian prospective, longitudinal study of a subset of patients who participated in a Phase III randomized trial comparing a 4 week course of (hypofractionated) radiotherapy with the then conventional 6.5 week schedule of radiotherapy for carcinoma of the prostate [13] will first be presented.

2.A retrospective study of the effects of pelvic irradiation for gynecological cancer on anorectal function [14]

As at least a third of patients, who have had pelvic radiotherapy for gynecological cancer are reported to suffer significant radiation bowel sequelae [1], anorectal function data from the above retrospective study will be presented next.

3.Argon Plasma Coagulation Therapy versus Topical Formalin for intractable rectal bleeding and anorectal dysfunction after radiation therapy for prostate carcinoma [15]

As rectal bleeding is the second most common reason for referral to a gastroenterologist after pelvic radiotherapy even though it impairs the ADL's of only 6% of patients [1], data from the only randomized trial of two current approaches used in the treatment of haemorrhagic radiation proctitis above will follow.

4.Pudendal nerve injury impairs anorectal function and health related quality of life measures ≥2 years after 3D conformal radiotherapy for prostate cancer [16]

Previous studies of the pathophysiology of anorectal dysfunction after radiotherapy for carcinoma of the prostate including our own have implicated weakness of the external anal sphincter (EAS) and internal anal sphincter (IAS), decreased rectal compliance, increased rectal sensitivity and faster distal colonic transit [2, 17, 18]. The underlying pathogenesis proposed for the *Pathophysiology, Natural History and Approaches to Treatment and Prevention of Radiation… DOI: http://dx.doi.org/10.5772/intechopen.99269*

observed changes in anorectal dysmotility is either myogenic or neurogenic. However, as muscle tissue particularly striated muscle constituting the EAS is more resistant to radiation damage than neural tissue [2], evidence of pudendal nerve injury after radiotherapy for prostate cancer is presented in the above study [16]. In addition, the editorial accompanying the publication states that the findings show the way forward for the restoration of bowel health of patients who have been adversely affected following pelvic radiotherapy for urological and gynecological malignant diseases [19].
