UPDATE 1-Roche's Herceptin gets EU backing in stomach cancer

* Herceptin prolongs lives of patients with stomach cancer

* Over 1 million cases of stomach cancer diagnosed each year

(Adds more details on drug and company)

ZURICH, Jan 28 (Reuters) - Roche Holding's (ROG.VX) cancer drug Herceptin has gained EU backing for patients with HER2-positive advanced stomach cancer, the world's largest maker of cancer drugs said.

The approval was expected after Europe's watchdog had already recommended extending use of the blockbuster drug for use against HER-2 positive stomach cancer in December. [ID:nLDE5BH16X]

"The approval is based on the impressive results from the international ToGA trial, which showed that treatment with Herceptin significantly prolongs the lives of patients with this aggressive cancer," the Swiss drugmaker said on Thursday.

The overall survival for patients with high levels of HER2 in the ToGA study was 16 months compared with 11.8 months on average for patients receiving chemotherapy alone, the group said.

Herceptin, or trastuzumab, is already approved for use in the 25 percent or so of breast cancer patients whose tumours generate the HER-2 protein, which can fuel cancer growth. It had 2008 sales of $1.8 billion.

Stomach cancer is the second most common cause of cancer-related death in the world and is the fourth most commonly diagnosed cancer, with over 1 million cases of stomach cancer diagnosed each year, the Swiss drugmaker said. (Reporting by Katie Reid; Editing by Dan Lalor)