Virginia C. Livingston, M.D., who died in 1990, postulated that cancer is caused by a bacterium she called Progenitor cryptocides, which invades the body when "immunity is stressed or weakened." She claimed to combat this by strengthening the body's immune system with vaccines (including one made from the patient's urine); "detoxification" with enemas; digestive enzymes; a vegetarian diet that avoided chicken, eggs, and sugar; vitamin and mineral supplements; visualization; and stress reduction. She claimed to have a very high recovery rate but published no clinical data to support this. Scientists who attempted to isolate the organism she postulated found that it was a common skin bacterium. Researchers at the University of Pennsylvania Cancer Center compared 78 of its patients with similar patients treated at the Livingston-Wheeler Clinic. All had advanced cancers for which no proven treatment was known. As expected, the study found no difference in average survival time of the two groups. However, Livingston-Wheeler patients reported more appetite difficulties and pain . The treatment Livingston originated is now offered at the Livingston Foundation Medical Center in San Diego.