This study looked at probability framings on preferences for cancer treatment alternatives in which tradeoffs between quantity and quality of life are made. 129 healthy volunteers and 154 cancer patients indicated their preferences for a toxic or non-toxic treatment at varying survival probabilities. They were randomly assigned into 3 treatments: (1) a positive frame in which the probability of survival was given; (2) a negative frame in which the probability of dying was given; and (3) a mixed frame in which the probability of surviving and dying were both given.The cancer patients' preferences for the more effective toxic treatment was significantly stronger than the healthy volunteers. Both groups were significantly influenced by the level of probability that was presented. Preferences for the toxic treatment were weaker when the chance of survival dropped below 50%. This weakening preference below 50% survival was enhanced for subjects who responded in the negative frame. A negative frame or probability level below 0.5 seems to stimulate a "dying mode" type of value system in which quality, not quantity, of life becomes more salient in decision making.