The Soviet physiologist Lina Solomonovna Shtern (1875—1968) was the only defendant in the trial against the Jewish Antifascist Committee who was not sentenced to death; the circumstances surrounding the court’s leniency toward her have long remained unknown. Shtern was sentenced to five years in exile and even her belongings were not confiscated. Her story has become the stuff of legends and much speculation. My paper reconstructs the particular circumstances surrounding the court’s decision to give Shtern a more lenient sentence and considers how the politics of science in the late 1940s and early 1950s could have influenced this decision and helped Shtern elaborate her own strategy of survival. I argue that the main reason for sparing Shtern’s life was her essay “On Cancer” written in the prison cell in the late 1951—early 1952. My work is based on a careful analysis of documents from Shtern’s personal archive and of the context of Soviet and North American medicine.