NEW YORK (CNNMoney.com) - Merck, the second-biggest American drug maker, said on Friday that its experimental cervical cancer vaccine Gardasil can also prevent external genital lesions in women, including vaginal and vulvar lesions.

Gardasil, in late-stage studies, showed 100 percent efficacy in preventing the sexually-transmitted viruses that cause 90 percent of vaginal and vulvar lesions in young women, including genital warts, said Merck spokeswoman Kelley Dougherty.

This is in addition to the Gardasil results that Merck reported on Oct. 7: that the experimental vaccine has 100 percent efficacy in preventing the sexually transmitted human papillomavirus, which causes 70 percent of cervical cancer cases. This type of cancer kills about 3,900 women in the U.S. annually and nearly 300,000 worldwide, according to the National Cervical Cancer Coalition.

Merck filed Gardasil with the Food and Drug Administration on Dec. 1 and requested fast-track review process. Generally reserved for cancer treatments and other life-saving drugs, the FDA's goal for accelerated review is to reduce the average 10-month review process to six months.

Margaret McGlynn, president of Merck vaccines, called Gardasil "a major breakthrough in cancer protection" during an analyst meeting on Thursday. McGlynn said the company's vaccines would help drive expansion in the vaccine market to $18 billion in 2009 from $8 billion in 2004.

The company is awaiting FDA decisions on Rotateq, a vaccine for rotavirus which causes severe diarrhea in infants, killing 100 annually in the U.S. and 500,000 worldwide, and Zostavax, a vaccine for zoster, also known as shingles. On Dec. 14 and 15, these vaccines were recommended for approval by an FDA advisory committee, and the FDA follows the advice of its advisors most of the time.

Gardasil is one of the Merck's brightest lights as the company faces lawsuits, layoffs and the looming patent expiration of its top earner, Zocor. Merck faces 9,200 lawsuits from plaintiffs who blame Vioxx, the $2.5 billion arthritis painkiller Merck pulled off the market in 2004, for heart attacks, many of them fatal. So far, Merck lost the first state case but won the second. The third case, in federal district court, was declared a mistrial. Merck has lost about a third of its stock value since the withdrawal.

Merck faces patent expiration next year on its top-selling drug Zocor, a cholesterol-lowering statin that totaled $5.2 billion in 2004 sales. The company must find new products to replace lost sales. Merck plans to save up to $5 billion through 2010 by cutting 7,000 jobs and closing or selling five plants.

Merck would not provide sales estimates for Gardasil. But many analysts consider Gardasil a potential blockbuster, though sales could be hampered by controversy. The vaccine has been tested in boys and girls as young as 10, and some parents might have moral objections against inoculating their pre-adolescent children for a sexually transmitted virus.

Merck (up $0.21 to $29.98, Research), based in Whitehouse Station, N.J., reported total sales of $22.9 billion in 2004.

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