Until John Paul II, the cause of a pope’s death was rarely made public. Even after a pontiff died, the Vatican did not officially disclose the cause. In more recent pontificates, by contrast, medical bulletins have documented illnesses and recoveries, increasingly shaping the way Peter’s successors govern. The removal of a malignant tumor has brought the Curia’s “K factor” into play — a reference to cancer, not communism, as former Italian President Francesco Cossiga once quipped.