He lived 15 months with an incurable brain tumor, a little longer than usual for a patient in his late 70s. Perhaps equally important is that Sen. Edward M. Kennedy lived those months well — able to work almost to the end, to sail the choppy New England waters he adored, to help elect a president he supported, and even to give him a dog.

Time is important to any cancer patient. Quality of life, not just how much life they can squeeze out, is increasingly the focus for people with a terminal illness, cancer specialists say. It also is one of the chief goals of treatments for brain tumors, since these therapies typically do not buy much time.

“The advances that we’ve made in prolonging survival aren’t as big as we’ve liked them to be, but people have stayed at a good quality of life right up to the end,” said Dr. Matthew Ewend, neurosurgery chief at the University of North Carolina, Chapel Hill.

Even after treatments can no longer control tumor growth for patients, “we can usually keep their quality of life pretty good with medicines for brain swelling, and then the end is usually pretty graceful,” Ewend said.

There is much to be admired in how Kennedy spent his final months, said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society.

“This is a man who had a serious and fatal illness and he knew that. Despite his illness, he carried on as best he could,” Lichtenfeld said.

He noted that celebrities “are public representatives of millions of people who deal with these issues on a daily basis.” When one gets recommended treatments and is able to live life to its fullest, it gives hope to other patients, Lichtenfeld said.

Kennedy received a diagnosis of malignant glioma, a cancerous brain tumor, after suffering a seizure at his home in May 2008. He had surgery two weeks later, followed by chemotherapy with the drug Temodar during and after radiation, his family has said.

Cancer specialists say he also likely received Avastin, a newer drug aimed at depriving the tumor of its blood supply. Avastin recently won federal approval for treating brain tumors that recur after standard treatment. It is made by Genentech, which recently was acquired by Swiss-based Roche.

Kennedy’s doctors have declined to comment on specifics.