Delia, P., Sansotta, G., Donato, V., Frosina, P., Messina, G., De Renzis, C., & Famularo, G. (2007). Use of probiotics for prevention of radiation-induced diarrhea. World Journal of Gastroenterology, 13(6), 912–915.

To examine the effect of probiotic use for prevention of radiation-induced diarrhea

The experimental group received high-potency probiotics (VSL#3 in one sachet) three times per day beginning on the first day of radiation therapy until the end of scheduled cycles. The VSL #3 sachet contained 450 billions/gm of viable lyophilized bacteria, including 4 strains of lactobacilli (Lactobacilli casei, L. plantarum, L acidophilus, and L. delbruekii subsp. Bulgaricus); 3 strains of Bifidobacteria (B. longum, B. breve, and B. infantis) and 1 strain of Streptococcus salivarius subsp. thermophilus.

The control group received an identical-appearing placebo.

This study reported on 490 patients receiving adjuvant radiation therapy after surgery for sigmoid, rectal, or cervical cancer.

This was a double blind, randomized, placebo-controlled trial.

Efficacy endpoints included incidence and severity of radiation-induced diarrhea, the number of bowel movements (BMs) per day, and the time from start of study until need for loperamide.

Endpoints (clinical symptoms, use of medications, and any adverse events) were reviewed with patients weekly during scheduled radiation therapy treatments and again one month after completion.

• In all, 97.5% of patients in the placebo group and 99.1% of patients in the experimental group completed study.
• More patients in the placebo group had radiation-induced enteritis and colitis (p < 0.001).
• The placebo group experienced more severe toxicity (grade 3 or 4) (p < 0.001) and had a higher mean daily number of BMs (p < 0.001).

Use of a probiotic lactic-acid producing bacteria is a safe, easy, feasible approach to preventing radiation-induced diarrhea after surgery for abdominal and pelvic cancer.

• Severity was assessed using World Health Organization (WHO) standards whereas other studies use National Cancer Institute (NCI) standards.
• This study looked only looked at prevention of radiation-induced diarrhea. 
• The study did not address safety in patients who are neutropenic.

Probiotic lactic-acid-producing bacteria is safe for use in patients receiving radiation treatment, and it is not associated with bacteremia, sepsis, or septic shock. Lactobacilli lowers the production of proinflammatory cytokines and other effectors of inflammation and tissue injury. Probiotic bacteria upregulates the innate immune response in the gut and protects against invasive organisms. Further studies are needed on different probiotic preparations and mixtures.