Radiation-Induced Diarrhea in Prostate Cancer Patients

Incidence and Duration

Diarrhea and loose stools are common after external beam radiation therapy (EBRT), typically affecting 25-50% of men following treatment 1
These symptoms can persist for two to three years after radiotherapy in some patients 1
Generally, about 60% of patients experience temporary mild diarrhea during pelvic radiation treatment 2
The Prostate Cancer Outcomes Study demonstrated that bowel side effects were more common among men who received radiotherapy compared to those who underwent radical prostatectomy 1

Radiation causes diarrhea through several mechanisms, including direct damage from energy absorption and free radical release from radiation interacting with cellular water 2
Injury to stem cells within intestinal crypts, leading to reduced mucosal integrity and flattening of intestinal villi 2
Modification of intestinal microflora and deterioration of enzymatic activities 2
Decreased absorptive intestinal surface area and reduced intestinal transit time 2
Possible lactose malabsorption that develops as a side effect of pelvic radiation 2
Cholerheic enteropathy from ileal dysfunction, with impaired bile salt absorption 2

Low BMI is a patient-related factor that influences the risk of developing radiation-induced diarrhea 2
Comorbid diseases, such as diabetes, hypertension, collagen vascular diseases, and inflammatory bowel disease, also increase the risk 2
Smoking history is another patient-related factor that contributes to the risk of radiation-induced diarrhea 2
Previous intestinal or abdominal surgery is a patient-related factor that influences the risk of developing radiation-induced diarrhea 2
Volume of small bowel in radiation field is a treatment-related factor that influences the risk of radiation-induced diarrhea 2
Radiation dose, with acute side effects to intestine occurring at 10 Gy and curative doses for pelvic tumors ranging between 50-75 Gy, is a treatment-related factor 2
Radiation technique, such as IMRT, is a treatment-related factor that influences the risk of radiation-induced diarrhea 2
Concomitant chemotherapy administration is a treatment-related factor that contributes to the risk of radiation-induced diarrhea 2

Acute diarrhea occurs during radiation therapy or within 3 months of treatment 2
Chronic diarrhea lasts for or develops after a longer period 2
Some studies indicate that bowel problems can linger for two to three years after radiotherapy 1

Nausea and vomiting are associated symptoms of radiation-induced diarrhea 2
Abdominal cramping is an associated symptom of radiation-induced diarrhea 2
Rectal tenesmus is an associated symptom of radiation-induced diarrhea 2
Bowel urgency and increased stool frequency are associated symptoms of radiation-induced diarrhea 1
Rectal pain, affecting 12-39% of men in the year after EBRT, is an associated symptom of radiation-induced diarrhea 1

Probiotics containing Lactobacillus species are suggested to prevent diarrhea in patients receiving radiation therapy for pelvic malignancies 3, 4
Systemic sulfasalazine is suggested to prevent radiation-induced enteropathy in patients receiving pelvic radiation 3, 5
Loperamide is used for symptomatic management of radiation-induced diarrhea 4
Dietary counseling is recommended to address potential nutrient malabsorption 4
Intravenous amifostine is recommended to prevent radiation proctitis 3, 5

Combining interstitial prostate brachytherapy with EBRT can result in higher rates of complications, including diarrhea, than treatment with brachytherapy alone 1