Positron emission tomography (PET) scans in mice can be used to determine whether a novel type of breast cancer treatment is working as intended, says a new study published in the July issue of The Journal of Nuclear Medicine.

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.

"Obtaining an accurate assessment of the HER2 expression levels in breast cancer tumors is absolutely essential to know whether treatment aimed at reduction of the protein levels in tumor cells is effective," said Jacek Capala, senior author of the study and investigator for the radiation oncology branch of the National Cancer Institute, National Institutes of Health, Bethesda, Md. "Our study indicates that PET could be a powerful tool both to identify patients who might benefit from targeted molecular therapies and to manage their care by measuring response to treatment. As research into HER2 therapies continues, similar techniques could be developed for other cancers overexpressing different proteins."

Much new research has been focused on developing therapies targeted to HER2. This protein is overexpressed in approximately 20 percent of breast cancers and also in some ovarian, prostate and lung cancers. Tumors that have an overabundance of HER2 protein are more aggressive and more likely to recur than tumors that do not overexpress the protein.