Effect of Intra-Tumoral Zinc Injection on Survival. Prostate cancer cell xenografts were placed into SCID mice and allowed to grow to a size of 200 mm3. Every 48 hours for 14 days, mice were then anesthetized and injected with 200 μL of either saline or 3 mM zinc acetate. Mice were evaluated by a blinded technician and sacrificed when tumor burden reached predetermined criteria for humane maintenance and care. Difference in mean survival between treatment and control groups was significant (p < 0.002) by Kaplan-Meier Survival Analysis.