Tehran University Medical Journal

Background: Several reports indicate that the probiotics can increase body resistance against malignant tumors. The aim of this study is to evaluate the effect of Lactobaci-llus reuteri Persian type culture collection (PTCC) 1655 in preventing tumor growth, improving weight and survival rate in mice with breast cancer.
Methods: Twenty mice, the BALB/c at six weeks age, weighing approximately 17 gram were divided into two groups. Oral administration of 500 micro liters of Lactobacillus reuteri suspension performed for the first group 14 days before tumor transplantation. The second group (control) received the same volume of phosphate buffer saline (PBS). Then the mice had tumor transplantation surgery. Lactobacillus reuteri was prescribed in the first group in seven-day period and three-day interruption pattern. At the same time the second group (control) received PBS. This process was continued until 45 day. The tumor growth, histology and body weight were evaluated in both group and the mortality of mice was recorded.
Results: In the mice transplanted tumors that had received probiotics, tumor growth decreased in comparison with control group. In this group the body weight increased (P>0/05). In addition, the survival of these mice had significantly increased compared to control group (P=0.002). The evaluation of tumor tissue also showed increased immune system function in mice receiving the probiotic (P>0/05).
Conclusion: Lactobacillus reuteri can improve immune system function and have an important role to help treatment of cancer.