Sentinel Lymph Node Biopsy Indicated in Thick Melanomas

March 2, 2015
Leah Lawrence

A single-institution study found that patients with melanomas of 4 mm thickness who had a negative sentinel lymph node biopsy had significantly prolonged survival.

Results from a single-institution study indicated that patients with melanomas of 4 mm thickness or greater who had negative sentinel lymph node biopsy (SLNB) had significantly prolonged survival compared with patients with positive SLNB.

Based on these results, Maki Yamamoto, MD, of the University of California at Irvine Medical Center, and colleagues concluded that SLNB is indicated in patients with thick, lymph node–negative melanoma.

“Despite consensus regarding the role of SLNB in patients with intermediate-thickness melanoma, controversy persists concerning those patients at the periphery of the primary tumor thickness spectrum,” Yamamoto and colleagues wrote in Cancer. “Given the observed survival differences between patients with SLN-negative and SLN-positive disease in the current study, we believe that there is valuable prognostic information obtained from this procedure.”

To evaluate SLNB, the researchers looked at 571 patients at their institution with melanoma of 4 mm thickness of greater and no distant metastases. Seventy-two percent of patients underwent SLNB, with 20% not undergoing biopsy, and 8.1% with lymph node–positive disease.

SLNB showed positive lymph node disease in 39.1% of patients, including those who underwent biopsy at an outside institution but were referred for further treatment. Looking at only those patients with SLNB performed at their institution, the researchers found lymph node–positive disease in 33.7% of patients. Fourteen patients at the institution who showed negative SLNB later developed disease recurrence in the mapped lymph node, equating to a false negative rate of 12.3%.

“On multivariable analysis, a primary tumor location in the trunk (odds ratio [OR] = 4.60; P = .0003) and extremity (OR = 3.17; P = .008) compared with a head and neck location, as well as the presence of satellitosis (OR = 10.31; P = .006), were found to be significant predictors of a positive SLNB,” the researchers wrote.

Looking at the entire study population the median recurrence-free survival was 21.1 months, disease-specific survival was 42.5 months, and overall survival was 62.1 months. Compared with patients with positive SLNB or clinically lymph node–positive disease, patients with negative SLNB had significantly improved median disease-specific survival  (41.2 months and 26.8 months vs 82.4 months; P < .0001), overall survival (34.7 months and 22 months vs 53.4 months; P < .0001), and recurrence-free survival (14.3 months and 6.8 months vs 32.4 months; P < .0001).

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