Prognostic Indicator for Cutaneous Melanoma: SNLB vs Breslow Thickness
A review of 896 patients who had undergone SLNB for primary localized cutaneous melanoma was conducted for this study.
Sentinel lymph node biopsy (SLNB) does not offer better prognostic and staging information than Breslow thickness (BT) in patients with cutaneous melanoma, according to the results of a retrospective, single-institution cohort study published in the Journal of the American Academy of Dermatology.
The investigators sought to compare the prognostic value of SLN status vs BT in patients with cutaneous melanoma. A retrospective chart review of patients who had undergone SLNB for primary localized cutaneous melanoma was conducted, with a total of 896 patients identified from electronic medical records between June 2002 and June 2016.
Mean patient age was 59.4; 42% of the participants were women and 97.2% were white. Demographic information, tumor features, SLNB results, and survival time were captured for all eligible patients.
With respect to BT, participants were divided into groups of 0.01 to 1.00 mm, 1.01 to 2.00 mm, 2.01 to 4.00 mm, and ≥4.01 mm. BT was recorded from a patient's initial biopsy, unless the wide local excision specimen revealed a greater thickness. Survival time was calculated as the difference between the initial biopsy date and either the participant's date of death or the date of the most recent patient contact. Kaplan-Meier estimates were used to determine 5-year overall survival (OS) rates.
Median patient follow-up was 30.3 months. The average BT was 1.2 mm, with 36.4% (326 of 896) of participants having tumors of ≤1.00 mm, 33.8% (303 of 896) with tumors between 1.01 and 2.00 mm, 19.2% (172 of 896) with tumors between 2.01 and 4.00 mm, and 10.6% (95 of 896) with tumors ≥4.01 mm. The majority of the tumors were on the trunk (35.7%) and upper extremities (24.1%).
Participants with a positive SLN status had significantly thicker tumors (P <.001). Of patients with BT ≤1.00 mm, only 7.7% had a positive SLN status, whereas in patients with BT ≥4.01 mm, 47% had a positive SLN status.
In patients with tumors between 0.01 and 1.00 mm, 5-year OS was 90.3%. In participants with tumors between 1.01 and 2.00 mm, 5-year OS was 87%. Moreover, 5-year OS was 76.5% in patients with tumors between 2.01 and 4.00 mm and 73.5% in patients with tumor thickness ≥4.01 mm. Although having a negative vs a positive SLN was associated with improved survival, none of the comparisons of the various tumor thicknesses conferred any statistically significant survival advantage.
The investigators concluded that SLN status may not be superior to the use of BT as a prognostic indicator of cutaneous melanoma, even though SNLB is the standard of care in many patients with melanoma. Ultimately, both BT and SLN status per univariate analysis were statistically significant in predicting cutaneous melanoma (P <.001 for both).
Stiegel E, Xiong D, Ya J, et al. Prognostic value of sentinel lymph node biopsy according to Breslow thickness for cutaneous melanoma [published online January 30, 2018]. J Am Acad Dermatol. doi:10.1016/j.jaad.2018.01.030