The evidence base for pelvic radiation disease risks and treatments remains limited; few clinical trials or prospective studies of pelvic radiotherapy have been published.1,3 Irradiation of nontarget, healthy tissues ultimately underlies pelvic radiation disease; however, total and per-fraction radiation doses, the volume of irradiated tissues, and concomitant administration of chemotherapy or biologic agents all appear to modulate risk.6
RISK ASSESSMENT
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Few data are yet available about how widespread use of radiotherapeutic modalities with improved targeting, such as intensity-modulated radiotherapy (IMRT), will affect the incidence of pelvic radiation disease.4 Early data suggest IMRT and 3D conformal radiotherapy are associated with late GI toxicity rates of 6% and 15%, respectively, among patients treated for prostate cancer; 3.6% and 3.0%, respectively, among patients treated for cervical cancer; 7% and 3%, respectively, among patients treated for anal tumors; and 9.5% and 20%, respectively, among rectal cancer patients also undergoing neoadjuvant chemotherapy.6 In general, chemoradiotherapy and radiation dose intensification can improve tumor control rates, but these also increase the risk of acute and chronic toxicities.4
Comorbidities and other patient factors also modulate risk. For example, diabetes nearly doubles the risk of pelvic radiation disease 5 years after radiotherapy.6 Tobacco use, inflammatory bowel disease, scleroderma, or a history of pelvic or abdominal surgery also appear to increase the risk of pelvic radiation disease.6
Detecting late toxicities following pelvic radiotherapy traditionally depends primarily on patients completing symptoms-based questionnaires, but these tools are problematic for several reasons.1 Questionnaire-based assessments cannot reliably distinguish symptoms that are radiotherapy-associated chronic toxicities from symptoms with other causes.1 Patients’ definitions of symptoms such as diarrhea can vary, as well; furthermore, patients sometimes deny stigmatizing conditions such as fecal incontinence. Patients should be educated before radiotherapy is undertaken and after its completion about the risks of late toxicity and that these effects may mimic other disorders.
“Patients may not be their own best advocates,” cautions Andreyev.1 They may deny symptoms they have taken drastic measures to prevent to avoid social embarrassment. For example, patients experiencing debilitating urgency of defecation may prevent fecal incontinence by never leaving the house; thus staying, at most, only a few seconds away from the bathroom, or not eating for many hours before they go out.
MANAGEMENT
Symptom management is based on gastroenterologic assessments and nurse-led patient needs assessments. Some patients may need a referral to a urology or gastroenterology specialist, hyperbaric oxygen services, a pain management team, or psychological support.1
In cases of extreme bowel obstruction, surgery may be necessary despite the fact that fibrotic scarring leaves patients with pelvic radiation disease at higher risk of complications from surgery.6 Endoscopic thermal coagulation therapy using argon plasma, laser, or heater probe can reduce pelvic radiation disease-associated bleeding; however, these treatments may cause pain, strictures, fistula, and perforation.6 Endoscopic formalin or cryoablation are also frequently used for bleeding, but these too have a risk of perforation, rectal ulcers, and pain.6
The term radiation proctitis implies that late pelvic radiotherapy toxicities are driven by inflammation, and this sometimes leads to inappropriate treatments with corticosteroids or other antiinflammatory agents, such as 5-aminosalicylic acids.6 These drugs do not offer any benefits to patients with pelvic radiation disease, according to a 2002 systematic review of clinical trial data.7
