Within the next few months, researchers at three medical centres expect to start the first test in patients of one of the most promising — and contentious — ideas about the cause and treatment of cancer. The idea is to take aim at what some scientists say are cancerous stem cells — aberrant cells that maintain and propagate malignant tumors.Although many scientists have assumed that cancer cells are immortal — that they divide and grow indefinitely — most can only divide a certain number of times before dying. The stem-cell hypothesis says that cancers themselves may not die because they are fed by cancerous stem cells, a small and particularly dangerous kind of cell that can renew by dividing even as it spews out more cells that form the bulk of a tumor. Worse, stem cells may be impervious to most standard cancer therapies.Sceptics say proponents are so in love with the idea that they dismiss or ignore evidence against it. Dr Scott E Kern, a leading pancreatic cancer researcher at Johns Hopkins University, said the theory is more akin to religion than science.At stake in the debate is the direction of cancer research. If proponents of the stem-cell theory are correct, it will usher in an era of hope for curing once-incurable cancers.If the critics are right, the stem-cell enthusiasts are heading down a blind alley that will serve as just another cautionary tale in the history of medical research.In the meantime, though, proponents are looking for ways to kill the stem cells, and say that certain new drugs may be the solution.“Within the next year, we will see medical centres targeting stem cells in almost every cancer,” said Dr Max S Wicha, director of the University of Michigan Comprehensive Cancer Center, one of the sites for the preliminary multiple-institution study that begins in the next few months.“We are so excited about this,” Wicha said. “It has become a major thrust of our cancer centre.”At the National Cancer Institute, administrators seem excited too. “If this is real, it could have almost immediate impact,” said R Allan Mufson, chief of the institute’s Cancer Immunology and Hematology Branch. The cancer institute is financing the research, he said, and has authorised Mufson to put out a request for proposals, soliciting investigators to apply for cancer institute money to study cancer stem cells and ways to bring the research to cancer patients. The cancer institute has agreed to contribute $5.4 million.Cancerous stem cells are not the same as embryonic stem cells, the cells present early in development that can turn into any cell of the body. Cancerous stem cells can turn into tumor cells and they are characterised by distinctive molecular markers.
