Valerie Harper, actress on ‘Mary Tyler Moore’ and 'Rhoda,' diagnosed with terminal brain cancer. The iconic actress was given a prognosis of three months to live by doctors. In the days before her shocking diagnosis of terminal brain cancer, Valerie Harper was struggling with lines she'd spoken countless times before. It was early January, and the beloved sitcom star who played wise-cracking Rhoda Morgenstern on The Mary Tyler Moore Show was in rehearsals for the national tour of Looped.