Improvements in melanoma treatment over the last five years may aid former President Jimmy Carter’s battle against the disease.
Carter has melanoma that has spread to his liver and brain, he announced August 20.
Melanoma is a type of cancer that starts in pigment-producing cells called melanocytes. Usually melanoma starts in the skin, but in some cases, there are no visible external signs of the disease. It also can begin in pigment cells in the eye or in mucous membranes in the mouth, sinuses, anus, vagina or other areas.
“Doctors tell me that about 98 percent of melanomas are skin cancer and about 2 percent are internal,” Carter said during a news conference.
Carter, who is 90, discovered in May that he had a slow-growing tumor on his liver. On August 3, he underwent surgery to remove the tumor and about one-tenth of his liver. A biopsy showed that the tumor was melanoma. An MRI revealed four small tumors, each about 2 millimeters wide, in his brain. The cancer may show up in other places and doctors will monitor him with scans of his body, Carter said.
“Looking at his pattern of spread, you can pretty much tell that this came from the skin,” says Anna Pavlick, a medical oncologist at New York University’s Perlmutter Cancer Center who is not involved in Carter’s medical care. His cancer may be one of the rare cases in which doctors can’t find the spot on the skin where the tumors began, she says.
Doctors may be able to use genetics to determine where the melanoma originated, says Tim Turnham, executive director of the Melanoma Research Foundation in Washington, D.C. Melanoma that originates in the skin usually bears genetic signatures of DNA damage from ultraviolet light.
The incidence of melanoma in the United States has been increasing, particularly among young people, mostly due to the rise of tanning culture, Pavlick says. The National Cancer Institute estimates that 73,870 people in the United States will be diagnosed with melanoma this year and 9,940 will die.
Unlike many skin cancers, melanoma can invade and spread through the rest of the body. “Melanoma has notoriously been the cancer that knows no boundaries,” Pavlick says. Most cancers spread to only certain other body parts, but melanoma has been known to invade gallbladders, hearts and other organs. “It just goes everywhere,” she says. “What makes it so aggressive, we just don’t understand.”
Carter will begin radiation treatment for the cancer in his brain and is taking a drug called pembrolizumab. That drug helps keep tumor cells in check. It stimulates production of immune cells called T cells that attack cancer cells. The drug also blocks proteins on the surface of melanoma cells that help them evade the immune system. “It’s like lowering the force field around the tumor cell so that the active immune system can get in and attack it,” Pavlick says.
Carter is fortunate that his melanoma didn’t happen a few years ago. “Had he received this diagnosis five years ago, he would have had almost no treatment options available to him,” Turnham says. “The only drug available at that time was so toxic that no one would give it to someone his age.”
Recently, researchers have discovered genetic drivers of melanoma (SN: 9/24/11, p. 18). About half of melanoma patients have a mutation in a gene called BRAF. Disabling that gene allows tumor cells to grow unchecked. Drugs that inhibit the mutant BRAF protein and other cancer genes have helped prolong patient lives, Pavlick says (SN: 9/25/10, p. 12).
Pavlick has been treating melanoma patients since 1999. “For the first 10 years, all I did was sign death certificates,” she says. Now, thanks to improvements in radiation, immune therapy and drugs that inhibit BRAF, about 50 percent of patients survive. And the treatments are not debilitating the way chemotherapy is. Carter will probably “tolerate this just fine,” Pavlick predicts.