Association of Histologic Regression in Primary Melanoma With Sentinel Lymph Node Status: A Systematic Review and Meta-analysis

Importance: The prognostic significance of regression in primary melanoma has been debated for many years. There is no consensus regarding the need for sentinel lymph node (SLN) biopsy when regression is present within the primary tumor. Objective: To review the evidence that regression may affect SLN status. Data Sources: A systematic review was performed by searching in MEDLINE, Scopus, and the Cochrane Library from January 1, 1990, through June 2014. Study Selection: All studies that reported an odds ratio (OR) or data on expected and observed cases of SLN positivity and histologic regression were included. Data Extraction and Synthesis: Primary random-effects meta-analyses were used to summarize ORs of SLN positivity and histologic regression. Heterogeneity was assessed using the χ2 test and I2 statistic. To assess the potential bias of small studies, we used funnel plots, the Begg rank correlation test, and the Egger weighted linear regression test. The methodologic quality of the studies was assessed according to the Strengthening of Reporting of Observational studies in Epidemiology (STROBE) checklist, and 2 different meta-analyses were performed based on those criteria. Main Outcomes and Measures: Summary ORs of histologic regression of primary melanoma and SLN status. Results: Of the 1509 citations found in the search, 94 articles were reviewed, and 14 studies comprising 10 098 patients were included in the analysis. In the combined 14 studies, patients with regression had a lower likelihood to have SLN positivity (OR, 0.56; 95% CI, 0.41-0.77) than patients without regression. On the basis of study quality, we found that patients with regression enrolled in high-quality studies had a lower likelihood to have SLN positivity (OR, 0.48; 95% CI, 0.32-0.72) compared with results of low-quality studies (OR, 0.73; 95% CI, 0.53-1.00). Examination of the funnel plot did not provide evidence of publication bias. Conclusions and Relevance: The results of this analysis showed that the risk of SLN positivity was significantly lower in patients with histologic regression compared with those without. Regression may be used in these cases to make a selection of which patients should be the most appropriate for this procedure.