Nonsentinel lymph node (NSLN) positivity appears to be a significant prognostic factor in patients with stage III melanoma, according to a study by Anna M. Leung M.D., of the John Wayne Cancer Institute at Saint John's Health Center, Santa Monica, California, and colleagues.

Regional lymph node metastasis in patients with primary cutaneous melanoma is the most important prognostic factor for tumor recurrence and survival. Sentinel lymph node (SLN) biopsy (a surgery that removes lymph node tissue to look for cancer) has become the one of the most important clinical tools in the staging of melanoma, according to the study background.

Among a total of 4,223 patients who underwent SLN biopsy from 1986 to 2012, a total of 329 had a tumor-positive SLN. Of these 329 patients, 250 (76 percent) had no additional positive nodes and 79 patients (24 percent) had a tumor-positive NSLN.

According to the study results, factors predictive of NSLN positivity included older age, greater Breslow thickness (the total vertical height of the melanoma, from the top of the area of deepest penetration into the skin), and ulceration. Median overall survival was 178 months for the SLN-only positive group and 42.2 months for the NSLN positive group (5-year overall survival, 72.3 percent and 46.4 percent, respectively). Median melanoma-specific survival (MSS) was not reached for the SLN-only positive group and was 60 months for the NSLN positive group (five-year MSS, 77.8 percent and 49.5 percent, respectively). NSLN positivity had a strong association with recurrence, shorter overall survival, and shorter MSS.

"We propose that, for the next iteration of the staging system, the committee performs an analysis of the independent prognostic impact of NSLN status," the authors write. "Should that analysis confirm the findings of our series and others, this sample, readily available data point should be included in the next staging system."