A new study published in the July issue of The Journal of Nuclear Medicine shows that positron emission tomography (PET) scans in mice can be used to determine whether a novel type of breast cancer treatment is working as intended. Researchers successfully used PET and a specially-developed radioactive compound to image HER2 - a protein often associated with aggressive breast cancer - in breast cancer cells before and after treatment aimed at decreasing HER2 expression. This molecular imaging methodology could facilitate development of new targeted therapies not only for breast cancer, but also for certain types of ovarian, prostate, and lung cancers that may be aggravated due to HER2.