Effect of PPP on disease-free survival. Mice were either untreated or treated with 50 mM PPP or the vehicle (DMSO/oil, 9:1) from the day of injection with 5T33MM onward. The first day of onset of morbidity was in the vehicle group on the 17th day. All naive mice were killed on the last day. The PPP group lived 10 days longer (P < .001 between vehicle group and PPP group).