Histological regression in primary melanoma: not a predictor of sentinel lymph node metastasis in a cohort of 397 patients.

BACKGROUND: Regression has been proposed as a potential marker of dissemination in thin melanomas. Previous studies have shown conflicting results.

OBJECTIVE: To determine if regression in melanoma is associated with an increased risk of sentinel lymph node (SLN) metastasis.

METHODS: A cohort analysis was conducted. Data on all patients were collected on a standardized case report form during 10 years. A total of 397 consecutive patients with melanoma who underwent a SLN biopsy were analysed. All cases of melanoma and SLN biopsies were examined by the same two pathologists. Differences between melanomas with and without SLN metastasis were compared using Fisher's exact test or the two-sample t-test and the chi(2) test. Multivariable logistic regression was used to adjust for possible confounding factors.

RESULTS: We analysed 397 patients (411 melanomas) who underwent a SLN biopsy. The median Breslow index was 1.8 mm (interquartile range 1.1-3). Regression was observed in 23% (n = 94). SLN metastases were observed in 26% (n = 106). The frequency of SLN metastasis was 16% in melanomas with regression and 29% without regression (P = 0.012). The adjusted odds ratio (OR) for regressive melanoma was 0.9 [95% confidence interval (CI) 0.4-1.9; P = 0.777]. The risk of SLN metastasis was increased in melanoma cases with a Breslow index from 1.5 to < 2.0 mm (adjusted OR 3.1; 95% CI 1.4-7.1; P = 0.006) and >or= 2.0 mm (adjusted OR 3.5; 95% CI 1.7-7.4; P = 0.001) and ulceration of the melanoma (adjusted OR 1.8; 95% CI 1.1-3.2; P = 0.03).

CONCLUSION: Regression is not an independent predictor of the risk of SLN metastasis in melanoma.