Why are probiotics good for cancer

Cochrane

background
Up to 80% of people treated with chemotherapy or radiation therapy experience diarrhea - one of the most common and difficult side effects. Severe diarrhea can lead to dehydration (loss of fluid and salt) and malnutrition due to changes in digestion and bowel processes and could negatively affect the quality of life. It has also been linked to an increased risk of infection in people with low white blood cell counts from cancer treatments. Diarrhea often leads to a delay in cancer treatment or a reduction in the dose or even withdrawal of medication. Foods that contain live bacteria or yeast (probiotics) may have a beneficial effect on the frequency and severity of diarrhea.

Aim of the review
Assess the effects of living microorganisms (probiotics) in preventing the occurrence or reducing the severity of diarrhea in people with cancer receiving chemotherapy or radiation therapy.

Main results
Overall, the studies we have found have not provided a clear answer as to whether probiotics reduce the incidence or severity of diarrhea, improve quality of life, or reduce the need for other medications. However, an analysis of only well-conducted studies has shown a beneficial effect on some endpoints.

With regard to the prevention of diarrhea compared to placebo in participants who received radiation therapy with or without chemotherapy, we do not come to any conclusion on the basis of the five corresponding studies as to whether probiotics have any benefit.

For the prevention of diarrhea from chemotherapy alone, three studies suggested that probiotic use may not reduce diarrhea, and one study reported reduced use of rescue medication for diarrhea.

Three studies comparing probiotics with other active substances found that patients who received radiation therapy with or without chemotherapy had a beneficial effect on the occurrence and severity of diarrhea and the need for rescue medication through probiotics.

Regarding the treatment of diarrhea due to radiation therapy, we only found one study that showed no clear effect of probiotics compared to placebo.

No study reported serious adverse events or deaths related to diarrhea.

Trustworthiness of the evidence
The quality (trustworthiness) of the evidence from the prevention studies was low to very low. The reliability of the evidence from the only study evaluating the effects of probiotics on the treatment of diarrhea was moderate.

What are the conclusions?
There is insufficient evidence on the effects of probiotics in preventing or treating diarrhea from cancer treatments. Still, probiotics seem safe as no study has found any serious side effects.