Matthew Ciorba, MD of Washington University School of Medicine in St. Louis, St. Louis, MO discusses how to use probiotics in cancer medical practice. More studies are needed to prove efficacy of probiotic products in cancer patient populations. Based on Dr Ciorba’s research, probiotics should be used as prophylaxis rather than therapy and should be started before the radiation treatment begins. Lactobacillus bacterial strain appears to have higher efficacy than Bifidobacteria species. In addition, appropriate dosing needs to be considered. Doctors should monitor patients closely and try to get involved in clinical trials. In the future, Dr Ciorba expects that we will be able to identify specific compounds from the probiotic bacteria and use them to create a more purified drug. Recorded at the Multinational Association of Supportive Care in Cancer (MASCC) and International Society of Ocular Oncology (ISOO) 2016 Annual Meeting on Supportive Care in Cancer held in Adelaide, Australia.