Irinotecan is one of key drug used in the treatment of colorectal cancer. The incidence of irinotecan induced diarrhea varies between 60-90%, with severe diarrhea in 20-40%. The main cause of diarrhea is one of irinotecan metabolites, SN-38 which is in the liver glucuronidated and subsequently expelled into the intestine. Due to the bacterial enzyme beta-D-glucuronidase in intestinal lumen it is deconjugated. This form causes direct damage of intestinal mucosa associated with malabsorption and the development of diarrhea. It is known that probiotic bacteria, reduce activity of intestinal beta-D-glucuronidase and therefore these bacteria could be applied in the prevention of diarrhea in patients treated by this food supplement. Given their low toxicity, good tolerability, probiotics may be an important part of supportive therapy. This is a first study aimed to determine the effectiveness of the probiotics in the prophylaxis of irinotecan induced diarrhea due to reduction intestinal beta-D-glucuronidase activity.

Inclusion Criteria:

• signed written informed consent
• histologically proven colorectal cancer patients started new line of chemotherapy based on irinotecan
• ECOG PS 0 - 1 at study entry
• life expectancy more than 3 months
• absence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule;

Exclusion Criteria:

• impossibility to take oral medication
• active infection treated by antibiotic therapy
• ileostomy
• hypersensitivity to study drug
• any concurrent malignancy other than non-melanoma skin cancer, no other cancer in past 5 years.
• serious concomitant systemic disorders or diseases incompatible with the study (at the discretion of investigator )