Washington ? Erbitux, the drug at the center of the stock-trading scandal that brought Martha Stewart to trial, won government approval Thursday as a last-ditch treatment for advanced colorectal cancer.

Doctors believe roughly 20,000 patients a year might benefit from Erbitux, one in a new type of cancer medicines that jam chemical signals that spur tumor growth.

But they caution that Erbitux is not a miracle drug. Patients have clamored for the drug since its roller-coaster attempts at Food and Drug Administration approval began in 2001.

“We hope for miracle drugs, but the reality is the way we make improvements in cancer is incremental,” said Dr. Ronald Blum, director of the cancer center at New York’s Beth-Israel Medical Center.

Erbitux’s advance is important, he said. It blocks a growth factor on colorectal tumor cells and enhances the punch of standard chemotherapy.

The FDA cautions that studies have not shown whether Erbitux can help patients live longer. But it can shrink some tumors and delay their growth, especially when Erbitux is used in combination with a common chemotherapy.

Bristol-Myers said it would begin shipping Erbitux in two weeks. The company would not release a price. Doctors and financial analysts have speculated the drug would cost about $30,000 for a year’s treatment.

Erbitux started making headlines in 2001 as manufacturer ImClone Systems became the darling of the biotechnology circuit, calling the drug a major advance. But in December of that year, the FDA rejected ImClone’s original application, saying the company’s studies were so poorly done that there was no way to tell whether Erbitux actually helped patients.

The rejection sent ImClone’s stock plummeting. Then came word that the company’s founder, Sam Waksal, was tipped to the rejection a day early and dumped his stock. He pleaded guilty to securities fraud and is in prison.

Stewart, his friend, is now on trial, accused of lying to investigators about why she sold her nearly 4,000 shares of ImClone around the same time as Waksal. She has denied wrongdoing.