Women with ductal carcinoma in situ (DCIS) who exhibit an overexpression of the protein HER2/neu have a six-fold increase in risk of invasive breast cancer, according to a new study from the University of Pennsylvania School of Medicine. The results, published in the journal Cancer Epidemiology, Biomarkers and Prevention, may help clinicians distinguish between DCIS that requires minimal treatment and DCIS that should be treated more aggressively.

"Not all DCIS is the same," says Brian Czerniecki, MD, PhD, Co-Director of the Rena Rowan Breast Center at the University of Pennsylvania and Surgical Director of the Immunotherapy Program for the Abramson Cancer Center. "From a practical standpoint, if you know that a patient has a greater chance of invasive cancer when you're doing a lumpectomy or mastectomy, then you might want to do a sentinel node biopsy, because there is a greater chance the cancer has spread to the lymph nodes."

DCIS accounts for more than 20 percent of all breast cancer diagnoses in the United States. While many of these premalignant lesions will progress to invasive disease, clinicians currently cannot predict which women are at greatest risk.