Nodal biopsy review

New York-The value of the sentinel lymph node biopsy lies in its ability to identify those melanoma patients with clinically negative regional nodal basins that have high-risk regional disease and may potentially benefit from completion regional lymphadenectomy and adjuvant immunotherapy, says Dr. Kathryn Spanknebel, assistant professor of surgery at Columbia University, who practices at Columbia University Medical Center.

More accurate stratification Sentinel lymph node biopsy procedures also allow for more accurate stratification of patients into homogeneous groups for prospective evaluation. Furthermore, sentinel lymph node biopsy may spare up to 80 percent of patients with pathologically negative sentinel lymph nodes the morbidity of unnecessary regional lymphadenectomy procedures, according to Dr. Spanknebel.

Speaking at the American Academy of Dermatology Academy '04, here Dr. Spanknebel reviewed the current indications for sentinel lymph node biopsy in patients with a diagnosis of invasive melanoma, the prognostic value of the procedure and the current prospective randomized trials testing its therapeutic value.

Sentinel lymph node biopsy has been established as a beneficial technique in breast cancer, which has led researchers to examine its utility for melanoma patients.

Nodal status is regarded as the single most important factor predictive of patient outcome. When the sentinel lymph node is negative, the predictive value for the rest of the nodal basin is excellent with a 1 percent to 2 percent false-negative rate and less than approximately 5 percent of patients having regional sentinel lymph node basin failure. Patients determined to have negative sentinel lymph nodes may be spared additional surgery and any adjuvant immunotherapy. Indeed, nodal status permits identification of patients who are eligible for adjuvant therapy, that being interferon alfa-2b.

Current indication Currently, sentinel lymph node biopsy is indicated for patients with invasive melanoma 1 mm to 4 mm by Breslow's thickness. Increasingly, thinner melanomas measuring 0.76 mm to 1 mm are being considered for sentinel lymph node biopsy, notes Dr. Spanknebel. About 5 percent to 10 percent of patients with primary melanoma tumors 0.76 to 1 mm in depth and up to one-third of patients with lesions thicker than 4 mm will have metastases in sampled regional sentinel lymph nodes.

"In general, we are performing sentinel lymph node biopsies for melanomas that are thinner and thinner, and in particular when other primary tumor features such as mitoses, ulceration or deeper Clark level are present," explains Dr. Spanknebel. "The majority of patients that dermatologists refer to the surgeon for a sentinel lymph node biopsy are those with intermediate melanomas. Any added prognostic value in patients with thick melanomas is quite controversial, as these patients typically are at high risk for not only regional nodal disease, but distant metastases as well."

MSLT Trial Dr. Spanknebel says trial known as the Multicenter Selective Lymphadenectomy Trial (MSLT), headed by Dr. Donald Morton, will reach maturity sometime soon and will hopefully shed much light on the role of sentinel lymph node-directed lymphadenectomy on survival benefit.

The goal of the study is to determine whether wide excision of the primary melanoma with intraoperative lymphatic mapping followed by selective lymphadenectomy will prolong overall and disease-free survival compared to wide excision of the primary melanoma alone and clinical surveillance of regional nodal basins.

Another question is whether patients with minimal microscopic disease in resected sentinel lymph node require completion lymphadenectomy at all. This will be addressed in the prospective MSLT II Trial, another multicenter study expected to open sometime this summer.