Systematic review of the prevalence of nodal metastases and the prognostic utility of sentinel lymph node biopsy in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer and its incidence is rising. The prognosis is mostly good but patients with high-risk cSCC have a greater risk of recurrence and death. The aim of the present study was to conduct a systematic review analyzing the prevalence, predictors and prognostic utility of sentinel lymph node (SLN) involvement in cSCC. We performed a published work search in Ovid MEDLINE and reviewed the reference lists of selected studies. Based on the 23 studies included in the systematic review, the proportion of patients with cSCC and positive SLN biopsy findings was 8% (95% confidence interval, 5.1-10.8%; I2 = 44.51%). We found no studies reporting on predictors of SLN involvement in cSCC or on the prognostic utility of this finding following adjustment for confounders. The rate of positive SLN in cSCC is less than previously reported. Criteria for recommending SLN biopsy as a staging tool for cSCC vary considerably from study to study, and none of the studies were large enough to reliably identify predictors of SLN positivity. No randomized controlled trials have yet analyzed whether SLN biopsy may improve the prognosis of cSCC. More studies are required on the prognostic value of SLN positivity and the associated risk factors in cSCC.