The type of treatment former President Jimmy Carter is receiving for brain cancer is designed more to provide quality of life than to prolong his life, according to one expert in the field.

Dr. Edward Halperin, the chancellor and chief executive officer of New York Medical College, said the prognosis for someone about Carter’s age with that type of metastatic melanoma is generally 2 to 6 months.

Halperin cautioned that every patient is different, so it’s hard to predict how much longer the former president might survive.

“No one person is a statistic,” Halperin told Healthline.

However, the radiation treatment and drugs Carter began receiving Thursday afternoon are most likely designed to minimize seizures, pain, and other symptoms of cancer.

“It’s done to improve quality of life as much as duration,” said Halperin.

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Carter’s Brain Cancer Is Somewhat Rare

Of the 1.6 million projected cancer diagnoses in the United States this year, about 74,000 will be melanoma. Of those melanoma patients, about 10,000 will die.

Halperin estimated there are 170,000 to 200,000 annual cases of metastatic cancer in the brain in which the cancer has traveled from another part of the body.

The most common types of cancer that reach the brain are breast cancer, lung cancer, and melanoma — the most deadly type of skin cancer.

Halperin said about 10 percent of these metastatic brain cancers are from melanoma — about 17,000 cases a year in the U.S.

Carter announced on Thursday that the cancer doctors cut out of his liver earlier this month had been found in his brain.

The 90-year-old former president said doctors had found four “small spots” of melanoma on his brain.

He began the first of four targeted radiation treatments on Thursday afternoon. Carter will also take an immune-boosting drug to fight the cancer.

Factors Not in Carter’s Favor

Halperin said there are four main factors that can determine how long a brain cancer patient might survive.

One is age. A patient over 65 years old has a higher chance of a worse prognosis than someone younger.

Another is overall health. An active person’s chances are better than someone in poor general health.

The number of metastatic cancer spots a person has will also affect his or her outlook. Patients with more than two or three such locales face worse odds.

The origin of the cancer also matters. Brain cancer that arrived from somewhere else is more dangerous than a primary brain tumor.

Carter is in good physical shape for his age, but he is well beyond 65. He also has at least four melanoma spots on his brain. And, although doctors aren’t sure where his cancer originated, it’s certain it came from another part of his body.

Treatments Are Relatively New

Carter will be receiving two types of treatment, both relatively new.

On Thursday, the former president received the first of four stereotactic radiation treatments. They will be administered three weeks apart.

The radiation is designed to attack the four small tumors and leave the rest of the brain alone.

Halperin said the procedure is delicate enough that Carter will have to wear a thermoplastic mask, much like an ice hockey goalie’s mask. That mask will be bolted to a table to keep Carter’s head from moving during the treatment.

“In this type of treatment, you want to hit what you want to hit and miss what you want to miss,” said Halperin.

On Thursday, Carter also received his first dose of the drug Keytruda to boost his immune system to attack the cancer.

Halperin noted the drug became available only last year, so it’s “unknown” whether it will be effective in prolonging Carter’s life.

Halperin said the treatment appears to be palliative care to reduce symptoms, rather than curative care to rid the body of a disease.

Carter, he said, is a highly functional 90-year-old who can probably enjoy most of the remaining months of his life with proper palliative care.

“You have to think of quality of life,” said Halperin. “In situations like these, it’s quite worthwhile doing.”