Sentinel Lymph Node biopsy

September 1, 2004

Few studies have addressed inter-observer variationin interpreting sentinel lymph node biopsy results.

New York - It has been more than 20 years since Donald L. Morton, M.D., and colleagues from the John Wayne Cancer Institute pioneered sentinel lymphadenectomy. Surgical oncologists say it has been perhaps the most important breakthrough in melanoma. Yet its role in clinical practice remains hotly debated. Not surprisingly, sentinel lymph node dissection for melanoma proved to be a major focus of melanoma symposiums at the Society of Surgical Oncology annual meeting.

Merrick I. Ross, M.D., was one of the more outspoken presenters who questioned using sentinel lymph node biopsy without a complete lymph node dissection. "It should never be used outside of a clinical trial," he says. Dr. Ross, a surgical oncologist from the M.D. Anderson Cancer Center in Houston, points out several disturbing trends in how sentinel node biopsy is used in the clinic.

"It may seem counterintuitive to perform a complete dissection; without it, sentinel node positive-patients may have microscopic disease," says Dr. Ross. "Therefore, they may recur in this lymph node group ... once patients develop palpable nodes, the ability to cure them and achieve locoregional control is compromised." Because the presence of lymph node involvement is the most powerful predictor of overall survival, dissections should be as accurate as possible for staging. "Low-risk patients you observe; high-risk patients you can be more aggressive with." Assuming that, a high degree of accuracy is required to optimize care.

Presenting a case, Dr. Ross showed the dangers of using sentinel lymph node biopsy without a complete dissection and starting interferon. A 40-year-old male with a 2.2 mm melanoma on the lower trunk and calf showed two-thirds of the sentinel node positive. Staging was negative. Without a complete dissection, 10 months later, the patient developed nodal disease; four months later, the patient developed iliac disease, recurrent dissected basin and pulmonary metastases.

Is jury out?

Many doctors have jumped on the bandwagon, advocating for sentinel lymph node dissection without performing an elective lymph node dissection - as they often do with innovative, minimally invasive techniques.

They argue that the sentinel lymph node dissection provides more complete lymph node staging because the sentinel node(s) can be examined in much greater detail. Additionally, they argue that the yield from a complete lymph node dissection is low; few people have non-sentinel node involvement (only about 10 percent to 20 percent). They also point to the added costs and added morbidity associated with an elective lymph node dissection (ELND). An ELND is an in-hospital procedure; a sentinel lymph node biopsy can be done on an outpatient basis. Wound infection, dehiscence, nerve injury, pain, joint dysfunction and lymphedema occur far more frequently with a complete lymph node dissection.

Dr. Ross acknowledges that as promising as sentinel node biopsy may look to its proponents, important questions must be resolved before it is adopted as the standard of care. "It is not clear whether a sentinel node biopsy can avoid the development of palpable disease," he says.

Dr. Ross says his point of view was not intended as an attack. He was quick to stress that sentinel node approach represents one of the most exciting surgical advances in the treatment of melanoma.