* U.S. sets Thursday briefing on breast cancer use
* Europe also could rule on Thursday
* Patients, lawmakers lobby FDA on Avastin
* $1 billion in sales at risk for Roche
* Roche shares down 0.5 pct (Updates with FDA briefing, stock activity)
By Lisa Richwine
WASHINGTON, Dec 15 U.S. health officials are set to announce their decision on whether Roche's ROG.VX top selling drug should be used to treat breast cancer, a ruling that places $1 billion in company sales at risk.
The Food and Drug Administration set a media briefing slated for 11 a.m. ET (1600 GMT) on Thursday on Avastin's use in advanced breast cancer.
An advisory panel urged the agency in July to remove breast cancer as an approved use after studies failed to show the drug extended survival or improved symptoms. The FDA usually follows panel recommendations.
The European Medicines Agency also may rule on Thursday at a monthly meeting of experts.
Avastin is the world's best-selling cancer medicine and one of the most expensive, a fact that fuels controversy. If the breast cancer approval is removed, the drug would remain available for treating bowel, lung, brain and kidney cancers. Doctors could still prescribe it for breast cancer, but insurers would be unlikely to pay the $8,000-a-month price tag.
The case has split patient advocates, and some lawmakers have accused the agency of trying to limit access to an expensive treatment. The FDA is not allowed to consider cost in approval decisions.
Britain already refuses to pay for Avastin for advanced breast cancer. The country's healthcare cost agency last week gave the drug a poor assessment. [ID:nLDE6B71VI]
Industry analysts estimate Roche could lose $1 billion of its $6 billion in annual sales if Avastin loses its U.S. and European licenses for breast cancer. Doctors could still prescribe the drug for breast cancer patients, but insurers would be unlikely to cover it without FDA approval.
Roche could request a hearing and appeal any FDA decision to remove the breast cancer use.
The company argues Avastin provides meaningful benefits for patients with few choices for fighting an advanced cancer.
"We continue to believe Avastin should be an option" for women with advanced breast cancer, said Charlotte Arnold, a spokeswoman for Roche unit Genentech.
Roche has an application pending with the FDA seeking approval of Avastin as a second-choice treatment for advanced breast cancer after initial therapy fails. The deadline for that decision is May 19.
Shares of Roche were down 0.5 percent at 140.50 Swiss francs. (Editing by Steve Orlofsky and Lisa Von Ahn)
DIARY-Emerging Markets Economic Events to April 28
--------------------------------------------------------------- MONDAY, MARCH 27 SYDNEY - RBA Deputy Governor Guy Debelle speaks at forex conference in Sydney - 2200 GMT. NEW DELHI - Global Business Summit (to March 28). TUESDAY, MARCH 28 SYDNEY - Reserve Bank of Australia Deputy Governor Guy Debelle to speak at the FX Week Australia conference - 2300 GMT. BUDAPEST - Hungarian Central Bank to discuss the final version of its inflation report. JOHANNESBURG - South African Reserve Bank star