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Key Words

Skin cancer, melanoma, lymph nodes, sentinel lymph node biopsy. (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary.)

Summary

Melanoma is more likely to be fatal if it has spread to the nearby lymph nodes. But only 20 percent of melanoma patients turn out to have cancerous lymph nodes; removing all of them as a matter of course can cause significant complications. In this study, a technique called lymphatic mapping and sentinel-node biopsy – which looks for cancer in a few nodes first – was better than a “watch and wait” approach in helping melanoma patients whose cancer had spread to the lymph nodes to live longer.

Source

American Society of Clinical Oncology annual meeting, Orlando, Florida, May 14, 2005.

Background

Melanoma is the most lethal form of skin cancer. Although it accounts for only about four percent of cases, it is the cause of most skin cancer deaths. Melanoma is most curable if it is detected and treated with surgery at an early stage, before the disease has spread to nearby lymph nodes and other organs.

If the cancer has spread to the lymph nodes, it’s important to remove them. But complete lymph node removal can cause chronic complications such as tissue swelling and numbness, and only 20 percent of melanoma patients actually turn out to have cancerous lymph nodes. For this reason, doctors previously advocated a “watch and wait” approach, where patients’ lymph nodes are monitored after the initial surgery and only removed if there are signs of swelling.

In the early 1990s, Donald L. Morton, M.D., of the John Wayne Cancer Institute in Santa Monica, California, proposed a new procedure for identifying patients with early-stage melanoma who have cancerous lymph nodes. When cancer spreads to the lymph nodes, it usually appears in some nodes (known as sentinel nodes) before others. Morton’s procedure, known as lymphatic mapping and sentinel node biopsy (LM/SNB), enabled doctors to identify the sentinel nodes, remove them, and test them for the presence of cancer. A study published in 1992 showed that patients almost never had cancer in other nearby lymph nodes if the sentinel nodes were cancer-free. Only if the sentinel nodes are found to be cancerous are all the nearby lymph nodes be removed.

Since that time, LM/SNB has been widely used to determine the stage of patients’ cancer at the time of diagnosis and to predict the likelihood of cancer recurrence. But a key question has remained: does the LM/SNB approach result in patients living longer than if cancerous lymph nodes are detected and removed later (the “watch and wait” approach)? In the current study, Morton and his colleagues set out to answer that question.

The Study

Between 1994 and 2002, the research team enrolled 2,001 patients with stage I melanoma in the United States, Europe, and Australia. The patients were randomly assigned to one of two groups. One group (the “watch and wait” group) had surgery to remove the melanoma followed by regular checkups to look for lymph-node swelling, a sign of disease spread. If spread was detected, patients then underwent surgery to remove all the nearby lymph nodes.

The second group had surgery to remove the melanoma plus LM/SNB to look for cancer in the sentinel nodes. In patients whose sentinel nodes contained cancer, all the nearby lymph nodes were removed soon after sentinel node removal. Patients whose sentinel nodes were cancer-free received no further treatment. To date, all the patients have been followed for a median of almost five years.

Results

When looking at all patients enrolled in the study – those in the LM/SNB group and those in the watch-and-wait group, regardless of whether cancer was ultimately found in their lymph nodes – patients treated with LM/SNB were 26 percent less likely to have a recurrence of melanoma after five years than those treated with the “watch and wait” approach. Patients in the trial will need to be followed for a longer period of time before it’s known whether there is a statistically significant difference between the two groups in terms of survival. Follow-up of patients in the study will continue for another five years.

A significant survival advantage was seen, however, when looking only at the 20 percent of patients in the study whose lymph nodes were found to have cancer. Among these patients, 71 percent of those treated with LM/SNB and immediate lymph-node removal were alive at five years, compared with 53 percent of those in the “watch and wait” group.

Patients in the “watch and wait” group had more cancerous lymph nodes on average (3.4) than those in the LM/SNB group (1.6), suggesting that additional spread of disease occurred during the “watch and wait” period, Morton said.

Having any cancerous lymph nodes was the most significant factor predicting patients’ likelihood of dying from melanoma within five years, Morton said. Patients who had at least one cancerous node were 2.6 times more likely to die of melanoma within five years than patients who had no cancerous nodes.

Note: Longer-term results from this trial were subsequently published in the Sept. 28, 2006, issue of the New England Journal of Medicine (see the journal abstract).

Comments

This is the first study to show that the LM/SNB approach to treating early-stage melanoma (removing nearby lymph nodes only if cancer is first found in a few sentinel nodes) does a better job than “watch and wait” at preventing disease recurrence and reducing deaths from melanoma in patients whose disease has spread to the lymph nodes, said Morton.

For all patients, Morton added, LM/SNB eliminates the need for regular checkups to monitor for disease recurrence in the lymph nodes and reduces anxiety about the possibility of the melanoma coming back.

“This important trial provides further evidence that sentinel node biopsy should be a standard component of the staging and treatment of patients with early-stage melanoma,” said Scott Saxman, M.D., of the National Cancer Institute’s Cancer Therapy Evaluation Program.

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