Researchers are fine-tuning an experimental breast cancer vaccine that may help eliminate 20 to 30 percent of breast cancers. The vaccine - tested in mice - eliminated tumors from HER2-positive cancer, a type of cancer that accounts for 20-30% of breast cancers. The vaccine even worked to eliminate HER2 tumors that had developed a resistance to drugs aimed at treating them. (Herceptin, an expensive antibody-based drug, is designed to treat HER2 tumors, but patients eventually develop a resistance to it.) [Reuters]