A Greek breast cancer patient is framed through a breast x-ray after a radiological medical examination in an Athens hospital October 29, 2008. REUTERS/Yannis Behrakis

Women with breast cancer lived significantly longer without their disease getting worse when treated with Bayer and Onyx Pharmaceuticals' cancer pill Nexavar, researchers said on Wednesday.

Nexavar, a targeted anti-cancer drug sold as a liver and kidney cancer therapy in more than 70 countries, beat analysts' expectations in the breast cancer trial, increasing the time patients lived without their disease progressing by 74 percent.

The magnitude of the benefit... suggests... this agent will be an important addition to our therapeutic armory in breast cancer, said Jose Baselga, head of oncology at Barcelona's Vall d'Hebron University Hospital and lead investigator of the study.

The Phase II trial showed that Nexavar, when combined with standard chemotherapy agent Xeloda, halted tumour growth for 2.3 months more than Xeloda alone, giving patients 6.4 progression-free months -- a result analysts described as impressive.

Results from the... trial testing Nexavar in metastatic breast cancer exceed expectations, said JP Morgan analyst Cory Kasimov in a research note.

Kasimov and other analysts got a first glimpse of the data in an abstract published earlier at Europe's largest cancer congress in Berlin. But detailed clinical data were unveiled on Wednesday at the ECCO-ESMO cancer congress.

Baselga told the congress his study showed the Nexavar combination with Xeloda, which is sold by Switzerland's Roche, had thrown up no new or unexpected side-effects, and the expected side effects were mostly manageable.

He said the fact Nexavar is a pill made it a unique and convenient treatment option.

Breast cancer is the leading cause of cancer deaths among women worldwide. According to American Cancer Society, there are around 200,000 new cases of breast cancer in the United States and 430,000 in Europe each year, and in 2007 some 1.3 million new cases were diagnosed across the world.

Nexavar is one of Bayer's most promising drugs, and the German drugmaker is aiming to generate worldwide sales of more than 2 billion euros ($2.9 billion) a year from it.

Bayer and U.S. biotech company Onyx are also testing Nexavar in further ongoing breast cancer studies and Bayer's oncology vice-president Dimitris Voliotis told the Berlin congress the two firms were committed to the development of Nexavar in breast cancer in a variety of settings.

Analysts said Nexavar's promise in early trials may open up opportunities for doctors to prescribe it off-label before it undergoes the final-stage trials that usually precede a license.