On Thursday morning, former President Jimmy Carter held a press conference in which he calmly announced that he was beginning treatment for metastatic melanoma. A small tumor had been removed from his liver during an operation on August 3, but scans had found four other small “spots” of the cancer, each about 2 millimeters in diameter, in his brain, he said. He was to begin radiation treatment later that day, he added, and had already begun taking an immune-system-boosting drug approved only last year for the treatment of advanced melanoma.
Carter, who will turn 91 in October, did not talk about his prognosis, but he described his diagnosis and treatment as “a new adventure.”
Melanoma is a type of skin cancer. It originates in pigment-producing cells, called melanocytes, in the basal (innermost) layer of the skin. The precise cause of the disease is unknown, but exposure to ultraviolet rays from the sun (and from tanning beds) is believed to be a major trigger of the DNA damage that leads to the cancer’s formation.
According to the National Cancer Institute, melanoma accounts for 4.5 percent of all new cancers in the United States. About 73,000 new cases will be diagnosed this year, and almost 10,000 people will die from the disease.
To learn more about melanoma, MinnPost spoke with Dr. Peter Lee, a dermatologic surgeon and associate professor at the University of Minnesota Medical Center. A lightly edited version of that discussion follows.
MinnPost: We think of melanoma as skin disease, not as a cancer that appears first in internal organs, such as the liver and brain. How would that happen?
Peter Lee: Melanoma is the deadliest form of the skin cancers that we treat. It’s usually caused by extensive sun exposure, although not all the time. In most circumstances, if caught early and if it’s just on the skin — and if you remove that portion surgically — then that’s typically a cure. But if the melanoma has invaded significantly and has travelled, via either the lymphatic [system] or the bloodstream, it can travel to other parts of the body, like the liver, like the brain, like the lung. It can then be fatal if not treated.
MP: But does it always start on an exposed area of the skin?
PL: Most commonly, someone would already have a history of melanoma that was treated on the skin. And, most commonly, those are on sun-exposed areas. But not always. We do see melanomas in areas such as the perianal regions or inside the mouth or even in the rectum, where there’s no sun [exposure]. Melanomas can arise from a mole that has changed. Or they arise on sun-damaged skin, out of the blue.
MP: It can also occur in the eye, correct?
PL: Yes. You can get melanoma on the surface of the eye or on the retina, in the back of the eye.
MP: Is that also caused by sun exposure?
PL: Usually, the ones on the surface of the eye are caused by sun exposure. But the ones on the retina, they can be from a preexisting mole. Those are probably not caused by the sun.
We do see a certain percentage of patients — actually quite a few — for whom we never find out what the source was. They present with metastatic disease. They have a seizure or headache or abdominal pain, and the next thing you know they have a melanoma on the inside of their body, and they’ve never had a history of anything being removed from their skin. And, on examination of their skin, there’s nothing that looks like a melanoma.
MP: Is that rare?
PL: It’s less common to not have a primary site. But we do see quite a few cases every year. It’s not an uncommon situation to have metastatic melanoma with an unknown primary [site on the skin].
MP: How important is a family history of melanoma to developing the disease?
PL: Definitely genetics plays a role in terms of how people are able to protect their skin from the sun — whether they are able to tan fairly easily or they burn frequently.
With President Carter, his family had a very strong pancreatic cancer history. [Carter’s father and three siblings died of pancreatic cancer, according to press reports.] There actually is a genetic link between pancreatic cancer and melanoma. It’s the p16 gene mutation.
MP: So that might be the link in President Carter’s case?
PL: It might be. You’d have to do genetic testing on President Carter and his family members. But there is definitely a link between pancreatic cancer and melanoma. When we do a history of our patients with melanoma, we always ask if they have a history of other internal malignancies that can be associated with melanoma.
MP: Melanoma is a very deadly form of cancer, but is there any recent research that looks particularly promising for treating it?
PL: Yes, it’s a very deadly disease, particularly if it involves the brain and the liver. But I would say that there have been huge advances in the treatment of melanoma, particularly over the past five years. And more treatments are on the way.
There are definitely very specific radiation treatments that people can do that target the tumor without damaging the tissue around it. As far as internal malignancies, the lesion can be removed surgically. But there are also many chemotherapy treatments now available that can be quite successful. Some are approved by the FDA, but others are available on a trial basis.
MP: One of the drugs President Carter is said to be receiving is called Ketruda, an immune-system-boosting drug that was approved for advanced melanoma just last year.
PL: Yes. There are basically two main types of treatment that are out there. One is to boost the immune system against the melanoma cells. The second one is to inhibit the growth of the melanoma cells. He may require both types.
MP: People need to take sun exposure seriously. Yet many people don’t. Do you get discouraged by continually having to warn people about protecting themselves from the sun?
PL: The behavior of the patients I see — and, actually, the behavior of people across the country — has changed in the past, say, 10 to 20 years. Twenty years ago, no one used sunblock. No one used hats and protective clothing. You never heard of clothing with an SPF factor. But they do make these specialized clothing now for people who are at high risk of getting skin cancer — not just melanoma, but the other skin cancers, too. People do wear hats. People wear sunglasses and use sunblock. Sunblock is much more readily available and more effective than it was 20 years ago. So society is making change.
In Australia, they had huge problems with skin cancer, and they still do, but [they launched a major] public awareness campaign, and it has worked. Hopefully, we’ll have our own major campaign down the road — particularly now that President Carter has been diagnosed.
MP: So you’re hopeful that the rise in the incidence of skin cancer that we’ve seen in recent years will start going down now that these behavior changes are occurring.
PL: That’s correct. Many of the younger people who have been getting skin cancer are young women who have been tanning indoors. We’re now seeing legislation get passed that bans tanning booths for anyone under the age of 18. Those things will help.
MP: Will President Carter’s age be a factor in his treatment and prognosis?
PL: President Carter is 90 years old. But I would say that age is not a factor in how you treat melanoma patients. It’s really all about their overall health. He’s healthy. He’s a vibrant person. I think they should do what’s necessary to try and eradicate his tumors. I have seen miracles happen with this disease, especially with the newer drugs that are out there.