Rare brain cancer believed to be linked to undercooked meat About 80 percent of malignant brain tumours are gliomas, and this could be contracted from contaminated water or undercooked meat. January 14, 2021 10:31 GMT Scientists discovered how a foodborne pathogen from contaminated water or undercooked meat may be linked to a rare type of brain cancer. Researchers discovered that people who have glioma have a higher chance of having antibodies against a certain type of bacteria called toxoplasma gondii as compared to those who do not have cancer. This gives an indication that the patients have previously been infected with a parasite believed to have come from undercooked meat.