The U.S. Food and Drug Administration approved a new drug to treat the most common type of kidney cancer on Tuesday, hailing it as a major advance in slowing tumor growth.

The drug Nexavar (sorafenib) made by German drugmaker Bayer AG and Onyx Pharmaceuticals Inc., helped curb the size and number of tumors, although it has not yet been shown to help patients live longer, the FDA said.

It is the first drug approved to treat advanced kidney cancer since 1992, FDA and company officials said.

“We believe that this represents truly, from a medical point of view, a major advance in the treatment of advanced renal cell carcinoma,” said Dr. Richard Pazdur, head of the FDA’s Office of Oncology Drug Products.

The drug kept the cancer from progressing for twice as long as a placebo in clinical trials - six months compared to three months, the company said.

The companies hope that further analysis of the data will show a survival benefit from Nexavar.

Those results were “probably one of the most impressive results I’ve seen in clinical oncology,” Pazdur told reporters during a conference call.

In fact, FDA officials were so impressed they allowed researchers in April to change the study to allow all 903 patients to take the drug.

“This drug represents, for Bayer, the first drug from our cancer franchise that has been approved,” said Dr. Susan Kelley, head of cancer product development Bayer’s healthcare unit.

As part of the approval, FDA’s Pazdur said the company will continue to study whether patients taking the drug live any longer than they would without the treatment. “It is too early really to make any comments ... about the survival effect of this drug,” he said.

Other drugs are used to treat the disease, including interferon and IL2, or aldesleukin. But the FDA said those can cause a number of complications, including fever, fatigue, fluid retention and other problems. They also do not work for all patients and results can be unpredictable.

More than 36,000 new cases of kidney cancer will be diagnosed this year, according to the American Cancer Society, and another 12,660 people will die from the disease, which rarely sees new therapies.

Nexavar, which works by blocking two types of enzymes that facilitate both tumor growth and blood supply, showed fewer side effects than the two current options, the FDA said.

Diarrhea, rash, hair loss and hypertension were among the most common side effects of the drug. Thirty-eight percent of patients taking the drug experienced more serious such episodes compared to 28 percent of those on placebo.

It will be available on the U.S. market by late Wednesday, Bayer also said. Studies are underway for use of Nexavar to treat liver and skin cancers.

Rival Pfizer Inc. is also working on an oral drug, Sutent, to treat kidney cancer and a type of stomach cancer. It filed for FDA review in August. Genentech Inc.‘s drug Avastin also is being studied for treating kidney cancer.