The Impact of Radiation Therapy on the Gut Flora
Radiation therapy may disturb the gut flora, which can cause diarrhea. There are many treatments for this, but they do not always work. We need new ways to treat this problem.
What are Probiotics?
The term “probiotic” refers to a product or preparation containing living microorganisms that are thought to have health benefits. They are found in some foods and supplements. Probiotics are sometimes called “good” or “helpful” bacteria because they help keep digestive systems healthy. Some research suggests that probiotics may help prevent or treat diarrhea or down-modulate the severity of intestinal inflammation in patients with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) by changing the composition and properties of gut indigenous flora.
This study was aimed to investigate the efficacy of a high-potency probiotic preparation in preventing or reducing the severity of radiation-induced diarrhea in cancer patients.
The Study Method on High-Potency Probiotics for Radiation-Induced Diarrhea
482 patients who underwent adjuvant postoperative radiation therapy after surgery completed this study. They were randomly assigned into two groups. 243 took the high-potency probiotic preparation VSL#3, while 239 had a placebo. Both products were consumed thrice a day, starting from the first day of radiation therapy until the end of the scheduled radiation therapy cycle.
Each sachet of VSL#3 contained 450 billion/gram of viable lyophilized bacteria, including four strains of lactobacilli (Lactobacillus casei, Lactobacillus plantarum, Lactobacillus acidophilus, and Lactobacillus delbruekii subspecie bulgaricus), three strains of bifidobacteria (Bifidobacterium longum, Bifidobacterium breve, and Bifidobacterium infantis), and one strain of Streptococcus salivarius subspecie thermophilus.
At baseline, patients provided their medical history and had a physical examination (consisting of vital signs, electrocardiogram, neurological examination, and laboratory testing). They were followed up weekly during the scheduled radiation therapy cycle and then a month after completion of radiation therapy. Clinical symptoms, concomitant medications, and any adverse events were noted at each visit, and laboratory studies were performed.
Efficacy endpoints were:
- Incidence and severity of radiation-induced diarrhea.
- The number of patients who discontinued radiotherapy because of diarrhea.
- The daily number of bowel movements.
- The time from the start of the study to the use of loperamide as a rescue medication for diarrhea.
Each patient was given a total X-ray dose of between 60 and 70 gray. The severity of gastrointestinal toxicity was measured according to World Health Organization grading, from grade 0 indicating no toxicity to grade 4 indicating severe toxicity with dehydration or hemorrhage.
More placebo patients had radiation-induced diarrhea than VSL#3 patients (51.8% vs. 31.6%). And among them, more patients in the placebo group suffered grade 3 or 4 diarrhea compared with VSL#3 recipients (55.4% vs. 1.4%). Daily bowel movements were 14.7 + 6 among placebo recipients and 5.1 + 3 among VSL#3 receivers. The mean time to use loperamide was 86 + 6 hours for placebo patients and 122 + 8 hours for VSL#3 patients.
There was no tumor- or treatment-related deaths or deaths from other causes from either group was observed during the period of radiation therapy, and no case of bacteremia, sepsis, or septic shock due to the probiotic lactobacilli was reported among the VSL#3 recipients during the treatment period and six months after active treatment. We did not recognize any other toxicity reasonably attributable to VSL#3.
Probiotic lactic acid-producing bacteria are an easy, safe, and feasible approach to protecting cancer patients against the risk of radiation-induced diarrhea.