Source: Medicalexpress.com Researchers at University Medical Center Utrecht, the Netherlands, have discovered a substance that has an adverse effect on nearly all types of chemotherapy - making cancer cells insensitive to the treatment. Chemotherapy often loses effectiveness over time. It is often unclear how or why this happens. It now appears that chemotherapy is made ineffective by two types of fatty acid that are made by stem cells in the blood. Under the influence of cisplatin chemotherapy, the stem cells secrete these fatty acids that induce resistance to a broad spectrum of chemotherapies. These substances are referred to by researchers as 'PIFAs' which stands for platinum-induced fatty acids. Cisplatin is a type of chemotherapy that is widely used for the treatment of cancer, including cancer of the lungs and ovaries. Tumors under the skin The researchers studied the effect of PIFA's in mice and human cells. The mice studied had tumors under the skin. Under normal conditions, the tumors would decrease in size following the administration of chemotherapy. In the study, after administering the fatty acids to the mice, the tumors were found to be insensitive to chemotherapy. The fatty acids were isolated from the medium in which chemotherapy exposed stem cells were grown. But also stem cells in the blood of patients produce the fatty acids that desensitize tumors to chemotherapy. The fatty acids are also found in commercially-produced fish oil supplements containing omega-3 and omega-6 fatty acids as well as in some algae extracts. In the experiments conducted [...]