Mapping Melanoma's Spread

MONDAY, Jan. 20, 2003 (HealthDayNews) -- People with melanomas on their face and neck might find out earlier whether the deadly cancer has spread, thanks to new research highlighting the safety and effectiveness of a special kind of skin mapping in this sensitive area.

They may also receive treatment faster if the mapping shows the disease has spread to the lymph nodes, notes one of the authors of the largest such study to date.

Once diagnosed by their doctor as having melanoma, "these people have no idea if it's reached beyond the initial site," says Dr. Carol Bradford, director of the University of Michigan's Head and Neck Oncology Program. "Early detection is crucial."

Bradford and her colleagues performed the delicate procedure on 80 patients diagnosed as having head and neck melanomas. While sentinel lymph node mapping (SLNM) is commonly used to detect the spread of melanoma in other places where this cancer is found, it's not routinely done on patients with head and neck melanomas because there are so many facial nerves, muscles and blood vessels in this area, Bradford says. "They're crucial to preserve," so the surgeon must be very familiar with face and neck surgery to perform SLNM, she explains.

Once a person has been diagnosed with a mole that is a melanoma, he is then referred to a specialist to investigate whether the cancer is spreading.

Aside from feeling a lump in the lymph nodes signaling that the cancer has spread, it's not possible to know if the cancer has spread without surgery, Bradford says. To date, many patients with melanoma go on to have surgical removal of areas around the mole, which may not be necessary if the cancer has not spread.

With SLNM, radioactive material is injected around the biopsy site. Using a probe that is "like a metal detector," doctors find areas that have trapped the radioactive material and mark them as places to make an incision. In the operating room, the patient is injected with blue dye. "Hot areas" -- those lymph nodes signaling as radioactive and blue -- are then removed and sent to pathology labs to determine if they are cancerous. In this study, the researchers were able to identify a range of hot areas, from none to seven, in each patient.

"Sentinel" in SLNM refers to draining lymph nodes, and they are usually the first areas where cancerous cells would go, Bradford explains.

In the study, cancer was "found to be present in lymph nodes 18 percent of the time."

However, four out of five patients did not have cancer that had spread, she says.

Patients were followed for a minimum of a year, although median follow-up was 25 months. A false-negative rate (people who were determined to have no cancer in their lymph nodes but who later found the cancer had spread) was 4.5 percent.

"We'd love it to be zero," Bradford acknowledges, but the procedure is "technically challenging" and makes errors more possible.

This study, which appears in the Jan. 20 issue of the Archives of Otolaryngology, may prompt other surgeons to perform more SLNMs in the face and neck area, Bradford hopes. None of the patients suffered facial paralysis or any other devastating effect from the procedure. "It's safe to biopsy around this area where the facial nerve resides," Bradford says.

The study suggests that SLNM "is pretty reliable," notes Dr. William Silver, vice president of the American Academy of Facial Plastic and Reconstructive Surgery. "The majority (of patients) were negative. The more of these we do and follow to develop more information, the more we avoid unnecessary surgery."

Silver adds he would like to see longer follow-up on the patients, because the third or fourth year after the melanoma is first identified seems to be key in determining whether the cancer has been eradicated.

Dr. James Hartman, an assistant professor of otolaryngology at the Barnes-Jewish Hospital in St. Louis, performs SLNM and considers it "a valid tool." The researchers looked at using a "pretty well-established technique for other parts of the body in our region, the head and neck," he says.

Because 75 percent of all melanomas are in the head and neck area, many patients stand to benefit from the use of SLNM in this region, Silver says.

More information

For more on melanoma, go to the Melanoma Patients' Information Page. Check out sentinel lymph node biopsy at the National Cancer Institute.