Isn't melanoma a skin cancer?
"Most melanomas occur on the skin, about 95 percent of them," and Jimmy Carter's cancer probably originated there even though no skin tumor may be apparent now, said Dr. Anna Pavlick, co-director of the melanoma program at NYU's Laura & Isaac Perlmutter Cancer Center.
Sometimes, the origin of melanoma cannot be determined. On very rare occasions, melanoma can start in mucus membranes or even the eye. But spread to the liver and the brain is not uncommon after a tumor that starts in skin, several cancer specialists said.
A skin cancer is not unlikely considering that Carter lives in the South, is fair-skinned and freckled, and through Habitat for Humanity and travel, has spent a lot of time outdoors — all known risks for melanoma, Pavlick said.
What can be done for him?
Carter said he will get two types of treatment — focused radiation to the tumors in his brain and a drug aimed at boosting his immune system. On Wednesday, he received the first dose of pembrolizumab, or Keytruda — a Merck & Co. drug recently approved for treating melanoma. It removes a sort of cloaking mechanism that cancer cells use to evade attack by the immune system.
"It's a wonderful drug," with relatively few side effects, as opposed to older, traditional chemotherapy drugs that cause hair loss and other symptoms, said Dr. Patrick Hwu, a melanoma expert at the University of Texas MD Anderson Cancer Center who helped test it and other immunotherapies.
Starting Thursday afternoon, Carter also will have four treatments, three weeks apart, of stereotactic radiation. It focuses beams precisely on tumors and avoids other areas of the brain and causes far fewer side effects than the whole-brain radiation common in the past. He was fitted with a customized mask to hold his head perfectly still to help make sure the radiation goes only where it is intended.
Is his cancer curable?
It is hard to say. "Every patient is going to be different," Hwu said. The key immune system cells needed to attack the tumor can get into the brain, so the treatment gives Carter a fighting chance, he said.
"There is a chance of cure," even with tumors in the brain, said Dr. Mario Sznol, a melanoma specialist at Yale Cancer Center.
As many as half of patients respond well to the immune system drug, "the highest activity we've ever seen" for a melanoma treatment, and many have remissions that can last many years, he said.