Prognostic Significance of Sentinel Lymph Node Mapping in Merkel Cell Carcinoma: Systematic Review and Meta-Analysis of Prognostic Studies

Abstract

Aim. To assess through a systematic review and meta-analysis of the literature the prognostic implication of sentinel lymph node mapping in Merkel cell carcinoma (MCC). Materials and Methods. PubMed and SCOPUS databases were searched by using “Merkel AND sentinel” as keywords. All studies with prognostic information regarding SLN mapping in cN0 MCC patients were included. Hazard ratio (HR) for overall survival (OS) and disease free survival (DFS) was used as effect size. Results. SLN biopsy predicted better DFS and OS as compared to the nodal observation in cN0 MCC patients (pooled HR for DFS: 1.61 (95% CI: 1.05–2.46), P = 0.028; pooled HR for OS: 1.08 (95% CI: 0.55–2.10), P = 0.8). Pathologically negative SLN (SLN−) patients had better OS (pooled HR: 4.42 (95% CI: 1.82–10.7), P = 0.0009) and DFS (pooled HR: 2.58 (95% CI: 1.78–3.73)) as compared to SLN+ patients. Conclusion. SLN mapping can provide strong prognostic information regarding OS and DFS in cN0 MCC patients. More importantly, SLN mapping can improve DFS and possibly OS in cN0 MCC patients as compared to nodal observation. As MCC is a rare tumor, large multicenter prospective studies are still needed to validate the survival benefit of SLN mapping.

Sentinel lymph node biopsy for cutaneous head and neck malignancies

“…This did not show any difference in prognosis for the HN subsite compared with other sites. This review also supports the hypothesis that there is a disease-free survival benefit to SLNB compared with observation (HR: 1.64; p = 0.028) [67]. This is an important consideration as the morbidity of uncontrolled regional disease can significantly worsen a patient's quality of life even in the palliative or end of life setting.…”

15-Year Experience of 18F-FDG PET Imaging in Response Assessment and Restaging After Definitive Treatment of Merkel Cell Carcinoma

“…Response-assessment scans highlighted both metabolic response and lymph node involvement as important prognostic factors for OS (adjusted P , 0.001 and 0.016, respectively). Recent literature has placed an emphasis on sentinel lymph node biopsy for prognostic information and disease-free survival improvement, compared with nodal observation in clinically node negative disease (24). The prognostic value of metabolic response of MCC after definitive treatment is a new observation and suggests that 18 F-FDG PET scans could be included as part of follow-up regimens to provide patients with a more accurate post-treatment prognosis.…”

“…They noted that a distinct advantage of 18 F-FDG PET was the ability to image the whole body in a single study and the detection of metabolic disease before lymph nodes become clinically evident. Sentinel lymph node biopsy is still, however, important to use in conjunction with 18 F-FDG PET, because these scans have been shown to miss nodal micrometastases (24,27). The low number of patients who had sentinel node evaluation in the response-assessment group is likely due to a high proportion having clinical lymph node involvement, some of the patients being staged before data showing the benefit of sentinel lymph node sampling and some patients having elective nodal treatment.…”

Lymphatic mapping and sentinel node biopsy in a patient with upper limb Merkel Cell Carcinoma: a case report and brief review of literature

“…Recurrence rate (overall regional and distant) was three times higher in sentinel node positive patients as compared with the sentinel node negative ones [4]. The last systematic review by Sadeghi et al in 2014 showed the prognostic importance of SLN mapping in cN0 MCC patients as sentinel node mapping can improve disease free and overall survival in cN0 MCC patients as compared with nodal observation [19].…”