UPDATE 1-Glaxo temporarily withdraws Avodart cancer filing

* Says needs to update data, unrelated to safety or efficacy

* Glaxo had filed for prostate cancer risk reduction Oct. 1

(Adds explanation for withdrawal, background)

LONDON, Nov 23 (Reuters) - GlaxoSmithKline (GSK.L) temporarily withdrew its application to U.S. regulators for a new use of its Avodart drug in preventing prostate cancer because of a technical problem with the file, it said on Monday.

"We identified data that needed updating -- and it's not in relation to safety or efficacy -- so we have withdrawn the file and will change it and then resubmit it," a company spokesman said.

Glaxo expects to resubmit the file shortly. A review of the European filings will begin once the same update has been provided to EU regulatory agencies.

The Britain-based drugmaker filed its supplemental new drug application for Avodart with the U.S. Food and Administration on Oct. 1, following positive results from a clinical trial in cancer prevention. [ID:nLR589373]

Avodart, which had sales of 399 million pounds ($663 million) in 2008, is currently approved to treat benign prostate enlargement.

Preventing prostate cancer, the second leading cause of male cancer death, could open up a substantial new market for Avodart, as well as reinforcing its position in benign disease. (Reporting by Ben Hirschler; Editing by David Holmes) ($1=.6020 Pound) ((ben.hirschler@thomsonreuters.com; Tel: +44 20 7542 5082; Reuters Messaging: ben.hirschler.reuters.com@reuters.net; www.twitter.com/reutersBenHir))