The gist: A recent clinical trial found that positron emission tomography (PET) scans could be used to predict how well a patient will respond to neoadjuvant (pre-surgery) treatment with chemotherapy and trastuzumab (Herceptin). Doctors might recommend a change in treatment to a patient whose PET scans show that current treatment isn’t working. In the study, researchers treated women with early-stage, HER2-positive breast cancer. Based on PET scans, the researchers were able to predict which patients would still have signs of an invasive tumor after treatment. They also found that adding the drug bevacizumab (Avastin) to the treatment plan could improve responses for some of these patients.