Scientists Make Strides Against Melanoma

Main Category: Melanoma / Skin Cancer
Also Included In: Cancer / Oncology
Article Date: 25 Jul 2007 - 1:00 PDT

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Melanoma remains a stubborn foe, with doctors reporting limited success in preventing the sometimes fatal skin cancer and even less success developing a cure.

"We'd like to reduce that death rate, but that's not happening," said Dr. Martin A. Weinstock, chairman of the American Cancer Society's Skin Cancer Advisory Committee. "We're not being effective in preventing melanoma. We've been making progress in early detection but not as much as we would like. And therapy for melanomas not detected early is basically poor."

But several advances announced in the last year -- from testing "sentinel" lymph nodes as a way to jump-start aggressive treatment, to new gene therapies that may one day beat back the cancer -- have given doctors a cautious sense of optimism.

Still, the experts add that these treatments need more testing, and prevention remains the best way to avoid the disease. So, the message remains the same -- protect yourself from the sun, and keep an eye on unusual skin growths.

"There are a lot of therapies that are promising," said Weinstock, professor of dermatology and community health at Brown University and chief of dermatology at the VA Medical Center in Providence, R.I. "But they're all possibilities. We just don't know if they're going to pan out yet."

Skin cancers in general are extremely survivable. The U.S. National Cancer Institute estimates that more than 1 million new cases of non-melanoma skin cancer will be diagnosed in 2007, claiming fewer than 2,000 lives.

Melanoma is another matter. It's rarer than basal cell or squamous cell skin cancer, with about 59,900 new cases expected to strike Americans this year. But it will kill an estimated 8,110 people, according to the cancer institute.

Melanoma remains frustratingly hard to prevent and cure, Weinstock said.

It begins in skin cells called melanocytes that produce melanin, the pigment that gives skin its natural color. Skin exposed to the sun causes melanocytes to produce more pigment, creating a sun tan. Sometimes, clusters of melanocytes and surrounding tissues form moles on the skin.

Melanoma occurs when those pigment cells become malignant. The first sign of trouble often is a change in the size, shape, color or feel of an existing mole, with most melanomas displaying a black or blue-black area. Melanoma also can appear as a new mole that is black or looks abnormal or ugly, according to the cancer institute.

If undetected or left untreated, melanoma can spread to other parts of the body, such as the liver, lungs or brain. The first sign that melanoma has spread, or metastasized, usually is the appearance of cancer cells in the body's lymph nodes. Part of the body's defense system, the nodes produce lymph, which travels throughout the body and filters out impurities.

In the past, doctors fighting melanoma would remove many or all of the body's lymph nodes to help prevent the spread of the cancer. But the experimental sentinel node biopsy technique allows doctors to remove only a few lymph nodes directly affected by the melanoma.

In the procedure, a radioactive substance is injected near the melanoma and its progress through the body is tracked. The first lymph nodes to take up the substance are called the sentinel lymph nodes.

Since the cancer is most likely to head to those lymph nodes first, only those nodes are surgically removed for testing. If positive, the rest of the lymph nodes are tested and removed. But if negative, the patient avoids what can be a painful procedure.

Sentinel node biopsy has been around for about two decades, but new studies have shown that its use can give patients a better fighting chance against metastasized melanoma.

A 2006 study headed by Dr. Donald L. Morton, who helped create the technique, found that patients whose lymph nodes tested positive and then had the rest of their nodes removed enjoyed a much higher five-year survival rate, compared with people who tested positive but delayed removal of their lymph nodes.

"The risk of dying from melanoma was almost one-half reduced if you had the lymph nodes removed versus waiting for them to grow to a detectable size," said Morton, medical director and chief of the melanoma program at John Wayne Cancer Institute at Saint John's Health Center, in Santa Monica, Calif.

Other scientists have found that boosting the immune system's ability to recognize and destroy cancer cells shows promise in treating melanoma.

In a recent study, National Cancer Institute researchers treated 17 patients with advanced, metastatic melanoma with white blood cells called T-lymphocytes that had been genetically engineered to better recognize the skin cancer. The result: Two of the patients went into a sustained remission.

Doctors believe this shows that such gene therapy can work, but much more work and many refinements remain ahead.

Until these tactics are improved upon, Weinstock recommends that people use the American Cancer Society's recommended "Slip, Slop, Slap" strategy for fighting skin cancer.

"The one major avoidable cause of melanoma is exposure to ultraviolet radiation from the sun," Weinstock said. "Slip on a shirt, slop on the sunscreen and slap on a hat."

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