Discharge and odor from the belly button are most often considered to be symptoms caused by an infection in the umbilicus, which may occur with cancer but is not necessarily a precursor to cancer. 1. Umbilical folds are rich and easy to hide dirt, bacteria can grow and multiply, when scratching leads to skin breakage, it can cause superficial skin infection and umbilical infection. Common pathogenic bacteria include Staphylococcus aureus, Escherichia coli, etc. Clinical manifestations include redness and swelling of the umbilicus, purulent discharge, odor, etc., which may be accompanied by pain, itching and other symptoms. 2. Cancer can lead to the decrease of immunity of the body, which is easily attacked by external pathogens, and umbilical cord infection can occur, with symptoms of purulent discharge from the umbilicus and odor. However, this is not a specific manifestation of cancer and cannot be regarded as a precursor of cancer. Whether it is cancer or umbilical cord infection, it needs to be diagnosed by a medical professional.