ZURICH (Reuters) - A late-stage study showed that women with an aggressive type of breast cancer lived significantly longer when treated with Roche's new breast cancer drug Perjeta, the Swiss drugmaker said on Friday.

The phase III study found a combination treatment of the drugs Perjeta and Herceptin plus chemotherapy lengthened the amount of time women lived without their disease worsening, compared to those just treated with Herceptin and chemotherapy.

Perjeta, also known as pertuzumab, was granted approval by U.S. health regulators earlier this month.

Roche is hoping that it will become the standard treatment for women with a form of cancer known as HER-2 positive, which makes up about a quarter of all breast cancers and has no cure.

(Reporting by Caroline Copley)