CDC provides info about MS and Cancer risk Dr. Matthew M. Zack of the Division of Chronic Disease and Health Promotion for the Centers for Disease Control and Prevention has provided extensive references from MEDLINE that show studies of the risk of cancer associated with multiple sclerosis since 1966. One study from Norway has found an increased risk for breast cancer in multiple sclerosis patients. Another study found an increased risk for cancers in multiple sclerosis patients due to one type of treatment for multiple sclerosis. Other studies found no association or a decreased risk for all cancers in multiple sclerosis patients. Still other studies are more speculative hypotheses that need further testing to be conclusive.