WASHINGTON, Sept 9 (Reuters) - Novo Nordisk's drug liraglutide appears effective in treating obesity, according to a preliminary assessment by reviewers at the U.S. Food and Drug Administration released on Tuesday.

The report noted an imbalance in the number of breast growths in women who took the drug, but said the company's information neither supports nor denies the potential role of the drug in cancer promotion or progression.

Their review was posted on the FDA's website two days before a panel of outside advisers is scheduled to meet on Thursday to decide whether to recommend wider use of the drug for obesity. The FDA usually follows the advice of its advisors.

Liraglutide is already approved to treat Type 2 diabetes, where it is sold under the brand name Victoza. If approved to treat obesity, it could generate an estimated additional $1 billion in revenue, according to analysts.

(Reporting by Toni Clarke; Editing by Susan Heavey)