Marne Shafer thought her running days were behind her after she received a total gastrectomy, a surgical removal of the stomach and nearby lymph nodes. She braced herself for the worst.

At age 33, the mother of two and experienced marathoner, learned she has a CDH1 gene mutation, which is associated with high-risk of a rare type of stomach cancer called hereditary diffuse gastric cancer, as well as lobular breast cancer.