Patients with cutaneous melanoma (CM) on the trunk have a worse prognosis than those with extremity CM. One reason could be multiple or uncommon (outside axilla or groin) sentinel node locations (SNLs). We identified 859 patients who underwent sentinel node biopsy for trunk (n = 465) or extremity (n = 394) CM in three Swedish healthcare regions from 2000 to 2008. We collected patient, tumor, and sentinel node characteristics through clinical registers and medical records. We investigated the distribution of SNLs in a logistic regression model, and risk of overall and melanoma-specific death through 2011 in a multivariable Cox regression model. Trunk CM was associated with multiple SNLs (31 vs. 7 %; odds ratio [OR] 7.1; 95 % confidence interval [CI] 4.6-11.5; p < 0.001) but not uncommon SNLs (8 vs. 7 %; OR 1.1; 95 % CI 0.6-1.9; p = 0.75) compared with extremity CM. The increased risk of melanoma-specific death was confirmed for trunk CM (hazard ratio [HR] 1.9; 95 % CI 1.3-2.9; p = 0.003), especially on the upper back (HR 2.3; 95 % CI 1.4-3.6; p < 0.001) compared with extremity CM. Uncommon SNLs (HR 0.5; 95 % CI 0.2-1.4; p = 0.21) or multiple SNLs (HR 1.1; 95 % CI 0.4-2.9; p = 0.81) were not associated with melanoma-specific death compared with those with common/single SNL. Trunk melanomas were associated with multiple lymph drainage, but the worse prognosis of trunk melanomas could not be explained by the increased frequency of multiple or uncommon SNLs.
Subject classification (UKÄ)