字幕表 動画を再生する 英語字幕をプリント More than 100 years ago, a British doctor, John Beard, noted that cancer cells behaved much like human trophoblasts (embryonic cells), which are referred to today as stem cells. In 1911, he published a book called, “The Enzyme Treatment of Cancer and Its Scientific Basis,” in which he expounded on his theory that cancer was caused by these primitive precursor cells, and that enzymes could be used to treat the disease. Dr. Beard noticed that the placenta (which forms from part of the fertilized egg) had many similarities to a tumor, in that it exhibits uncontrolled and invasive growth. Some tumors, like placental cells, even secrete the hormone HCG. Placental cells multiply unchecked until the fetal pancreas begins secreting enzymes, at which point the placenta stops growing. This led Dr. Beard to the conclusion that enzymes might also inhibit the growth of tumor cells. Tests on mice implanted with tumors showed that injections of pancreatic enzymes caused their tumors to shrink. Dr. Beard then tested enzymes on human patients, with positive results. However, Dr. Beard’s theory never caught on with the scientific establishment, and he died in obscurity in 1924. However, it appears that Dr. Beard was correct all along. New research shows that tumors do in fact originate from stem cells, which form the basis for the recurrence of tumors, and also for the development of chemotherapy resistance. Most forms of chemotherapy and radiotherapy kill only the quickly-dividing progeny of cancer stem cells, temporarily destroying the bulk of the tumor. However, if even one stem cell survives, it will soon recreate the original tumor.