US health regulators expanded the approval of Roche Holding's breast cancer drug Perjeta and will now allow its use to help shrink tumors prior to surgery, the Food and Drug Administration said on Monday.

The decision followed a 13-0 vote by an FDA advisory panel earlier this month in favour of the expanded approval.

Perjeta was originally approved in 2012 to treat patients with advanced or late-stage HER2-positive breast cancer. It can now be used prior to surgery in patients with HER2-positive, locally advanced, inflammatory or early-stage breast cancer who are at high risk of having their cancer return or spread, the agency said.

"By making effective therapies available to high-risk patients in the earliest disease setting, we may delay or prevent cancer recurrences," Dr Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA Center for Drug Evaluation and Research, said in a statement.

Under the expanded approval, Perjeta, known chemically as pertuzumab, would be used in combination with Roche's older breast cancer drug Herceptin and chemotherapy prior to surgery.

Herceptin has long been used to treat HER2-positive breast cancer to reduce the risk of disease recurrence. About 20 per cent of breast cancers have an abundance of the HER2 protein and tend to be aggressive, faster growing cancers.

Following surgery, patients who had been treated with Perjeta should continue to take Herceptin for a year, the FDA said. - Reuters