Scientists are discovering a new potential ally in the fight against cancer: The trillions of bacteria that live in the human body. According to a recent study bacteria found in the gastrointestinal tract were as effective as an immunotherapy in controlling the growth of skin cancer. Scientists in France also found that some bacterial species help to activate responses to immunotherapy. More studies are expected to investigate the entire microbiome of bacteria within the body to develop cancer treatments based on bacterial secretions.