McGrath first learned she had breast cancer in 1997 at the age of 31. Following a mastectomy, chemotherapy and radiotherapy, she was deemed cancer-free by June 1998. Despite fears that cancer treatment may have left her sterile, she later gave birth to two children who were both breast-fed. In 2003, McGrath was diagnosed with metastatic disease in her bones. In 2004, she appeared with her husband on Andrew Denton's Enough Rope on the ABC, describing her work for the foundation and her personal experiences.