They identified 36 patients with mutations that fit their criteria for mosaicism-those that were present in a fraction of blood cells and in a higher fraction in tumor cells.įollow-up analyses suggested that the mutations likely had a major role in the growth of the patient’s tumors. The research team scoured the test results of more than 35,000 patients, both children and adults, for mosaic mutations in cancer susceptibility genes. That allows them to find mosaic mutations present in both blood and tumor cells, she explained. “The breakthrough here with MSK-IMPACT is we are doing paired samples, so we have the blood and the tumor alongside each other,” Dr. Every patient at MSKCC gets the test to identify potential treatments that might help them or clinical trials they might be able to join. Using MSK-IMPACT to find mosaic mutationsįor the study, the scientists tapped into data from MSK-IMPACT, a genetic test that scans more than 500 cancer-related genes (including 61 cancer susceptibility genes) for harmful mutations. “But with the we employed, we were able to detect these mosaic mutations that were missed before,” Dr. Mandelker noted, due to technical limitations of conventional genetic tests. The contribution of mosaic mutations to cancer hadn’t been given much thought because they’re typically overlooked, Dr. But this new study, partially funded by NIH, could change that view if the findings are confirmed in other studies, he said. “The general school of thought was you either have germline mutations or somatic mutations,” Dr. Because each embryo cell goes on to form a specific set of organs and tissues-muscles and bones, for example-these mosaic mutations are present in some cells in the body as well as in the tumor.īefore this study, “I don’t think there was much consideration of this early embryonic mosaicism” among cancer researchers and doctors, said Ian Fingerman, Ph.D., of NCI’s Division of Cancer Biology, who wasn’t involved in the work. Previous studies have hinted that cancer-related mutations can also occur after conception, early in embryo development. Inherited, or germline, mutations are present in every cell in the body as well as in the tumor. Those mutations, known as somatic mutations, are found in the tumor but not in other cells in the body.įor a smaller group of people with cancer, the mutated gene was inherited from a parent at conception. When that mutation arises, however, can vary.įor most people with cancer, the mutation occurred later in life, sometimes years or decades after birth. Overlooked mutationsĬancer starts with a cell that has a harmful mutation in a gene that controls how cells grow and divide. Mandelker noted, and they hope other cancer centers will follow suit. The research team will continue to check for mosaic mutations in every patient who is treated at MSKCC, Dr. It can help determine the most appropriate cancer treatment and might also indicate the need to monitor for the growth of additional cancers. The study was published April 1 in Cancer Discovery.įinding out whether someone has a mosaic mutation in a cancer susceptibility gene is important for their cancer care, noted the study’s lead scientist, Fresia Pareja, M.D., Ph.D., of MSKCC. Looking through the genetic test results of more than 35,000 people with cancer treated at MSKCC, the team found 36 patients with mosaic mutations in cancer susceptibility genes. “What we found here is that mosaicism affecting cancer susceptibility genes is much more widespread than we previously anticipated,” said Senior Scientist Jorge Reis-Filho, M.D., Ph.D., also of MSKCC. ![]() Mosaic mutations in cancer susceptibility genes have been reported in rare cases in the past, explained Senior Scientist Diana Mandelker, M.D., Ph.D., of Memorial Sloan Kettering Cancer Center (MSKCC) in New York.īut “we had no idea what the extent of this phenomenon was in cancer patients we’re seeing every day,” Dr. But the new study highlights that these mutations can also occur after conception, as a result of spontaneous errors that happen as cells divide. Mutations in cancer susceptibility genes, which are known to increase cancer risk, are typically thought to be inherited, meaning passed from parent to child. As such, mutations that pop up during embryo development are aptly called “mosaic mutations.” ![]() But the unexpected part of their finding was when the mutations occurred: in the womb, during the earliest days of embryo growth.īecause each embryo cell grows to form a portion of the body’s organs and tissues, mutations that occur in the womb wind up in a mosaic, or patchwork, pattern in the person’s body. The culprit is mutations in genes known to be related to cancer ( cancer susceptibility genes). Scientists may have pegged a somewhat surprising cause of cancer for some people, according to a new study.
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