UPDATE 2-Roche's Avastin helps in ovarian cancer

* Avastin positive results in Phase III in ovarian cancer

* Comes just days after Avastin set back in stomach cancer

* Stock eases 0.2 pct

(Recasts, adds analyst comment, shares, background on Avastin)

By Katie Reid

ZURICH, Feb 25 (Reuters) - Roche's (ROG.VX) Avastin helps women with advanced ovarian cancer live longer without their disease getting worse, a late-stage study showed, boosting its prospects after a recent setback in stomach cancer.

Roche, the world's largest maker of cancer drugs, said on Thursday it was the first positive Phase III study of an anti-angiogenic therapy, which uses drugs to stop tumours from making new blood vessels, in advanced ovarian cancer.

It is a timely boost for the medicine after Roche said earlier this week Avastin had failed to reach its main target in a stomach cancer study, which some analysts said could cut core earnings by 1 to 4 percent. [ID:nLDE61M05O]

"This is a positive catalyst for Roche and further supports the Avastin franchise, especially welcome after failure of Avastin in the gastric cancer setting," said Vontobel analyst Silvia Schanz.

"We estimate peak sales of 1 billion Swiss francs for the indication ovarian cancer," she said. "The phase III trial of Avastin in prostate cancer is expected to read out later this year."

At 0958 GMT, Roche stock was trading down 0.22 percent at 179 Swiss francs, compared with a flat DJ Stoxx European healthcare index .SXDP.

Ovarian cancer is the sixth most commonly diagnosed cancer in women and the eighth leading cause of cancer death among women worldwide, Roche said, adding each year an estimated 230,000 women are diagnosed with the disease and some 140,000 die.

The Phase III study showed women with advanced ovarian cancer who are treated with Avastin and chemotherapy and then continue to take Avastin live longer without their disease worsening than if they only have chemotherapy.

Roche will present the data at the American Society of Clinical Oncology annual meeting in June.

Avastin, which works by starving tumours of blood and is made by the recently acquired Genentech unit, is used to treat lung, colon and breast cancers, and had 2009 annual global sales of 6.2 billion Swiss francs ($5.7 billion).

Its sales are seen hitting $8.5 billion by 2013 as Roche expands its use into different types of cancer, according to consensus forecasts from Thomson Pharma. ($1=1.080 Swiss Franc) (Editing by Jon Loades-Carter and Hans Peters )