For some women diagnosed with breast cancer, low muscle mass may be linked with a poor long-term prognosis, a new study has found. In one of the largest investigations of its kind conducted to date, researchers found that one-third of the women included in the study had low levels of skeletal muscle mass—a condition known as sarcopenia—at the time of their diagnosis. And having low levels of muscle mass was associated with a higher risk of dying compared with women who had adequate muscle mass, the researchers reported April 5 in JAMA Oncology. All of the women included in the study had breast cancer that had not yet spread beyond the breast at the time their cancer was diagnosed. The high proportion of women in the study with sarcopenia suggests that low muscle mass “is underappreciated” in women with earlier-stage breast cancer, said the study's lead investigator Bette Caan, Dr.P.H., of the Kaiser Permanente of Northern California Division of Research. The study also suggests that low muscle mass is as prevalent in patients “and is as strongly associated with decreased survival" as high levels of fatty tissue, or high adiposity, she continued. In a similar study led by Dr. Caan, sarcopenia at diagnosis also was linked with worse survival in people with nonmetastatic colorectal cancer. According to Joanne Elena, Ph.D., M.P.H., of NCI's Division of Cancer Control and Population Sciences, these studies are adding to the growing evidence that “low muscle mass may be another way to help identify patients at an increased risk for poor outcomes."