Rep. John Edward Grotberg, a first-term GOP congressman from Illinois being treated for colon cancer, shows signs of winning his fight against cancer but has fallen into a coma because of complications arising from a new cancer treatment, aides and doctors said yesterday.

The 60-year-old Grotberg has been in a coma for the last week at the National Institutes of Health (NIH), where doctors said he developed an infection from a catheter injected into his left arm to administer an experimental cancer therapy.

"There is a chance he will recover, and there is a chance he will die without regaining consciousness," said Dr. Steven A. Rosenberg of the National Cancer Institute, who developed the treatment used on Grotberg.

Rosenberg said that Grotberg has recovered well from the side effects of the cancer treatment itself and that his "remaining cancer showed evidence of further shrinkage."

"This is what is so maddening and frustrating," said Steve Trossman, news secretary in Grotberg's congressional office. "He is fighting the cancer and showing such great results and then this . . . now cancer is the least of his worries."

Of an estimated 50 persons who have received this particular cancer treatment, one person has died as a result of the serious toxic side effects that can accompany the therapy, Rosenberg said. That person's identity has not been disclosed.

Grotberg is the only one of the 50 to have developed a complication that led to a coma, Rosenberg said.

The cancer treatment, which was described in the Dec. 5 issue of the New England Journal of Medicine, uses natural substances to stimulate the body's immune defenses to fight cancer.

The news of Grotberg's condition broke as NCI officials announced an expansion of the therapy program to treat as many as 300 patients during the next year. Six additional medical centers in other parts of the nation will begin in the next two months to test the cancer treatment that so far has been available only through the NIH's Clinical Center, officials said.

Patients selected in the past to receive the therapy have been those with advanced cancer who failed to respond to other treatments, Rosenberg said. In addition, they also had the kinds of cancer and cancer locations that seemed to respond to this therapy, he said. Those included the colon cancer that Grotberg has struggled against for 12 years, Rosenberg said.

Grotberg has undergone surgery several times as a treatment for his cancer, but the condition has recurred, Rosenberg said. The latest treatment was completed Jan. 13, Rosenberg said, and the catheter tube used to administer the treatment was removed from the artery in Grotberg's left arm.

Medical records show that Grotberg had a fever the next day, Jan. 14, and that he was given antibiotics, although not enough to overcome the infection that was apparently causing the fever, Rosenberg said.

One week later, on Jan. 21, a series of X-rays enabled doctors to locate the source of the infection as the artery in Grotberg's left arm, Rosenberg said. Grotberg underwent surgery that same day to have the infected artery removed.

But six days later, on Jan. 27, "due to sudden major bleeding at the arterial stump, due to continued infection," Grotberg stopped breathing, suffered a cardiac arrest and then lost consciousness, Rosenberg said.

"He has not regained consciousness since," Rosenberg said.

Doctors meantime were able to stop the bleeding and start Grotberg's heart beating again. But his neurological status is not clear. "His brain is certainly alive," Rosenberg said, "but we cannot assess now whether there has been any damage of brain function."

Trossman said that Grotberg's staff in Washington is continuing to serve the 550,000 people who live in the far western Chicago suburbs and rural areas of his district. The staff working for Grotberg, the father of five grown children and several grandchildren, is "taking the lead from the doctor, and the doctor says there is a chance he can recover," Trossman said.