Sentinel lymph node biopsy in Merkel cell carcinoma: A multi-institutional study from the Pan-Canadian Merkel Cell Collaborative.

Abstract

9583 Background: There is controversy regarding sentinel lymph node biopsy (SLNB) in clinically node-negative Merkel Cell Carcinoma (MCC). We compared MCC recurrence and survival between patients who did versus did not undergo a SLNB. Methods: Patients with MCC across 13 Canadian centers were reviewed, from 2000-2018. Of a total cohort of 750 patients, 485 had clinically node-negative disease at presentation. A propensity score was created. The association between SLNB and local, regional and distant recurrence, and cancer-specific and overall survival were evaluated using competing risks and Cox proportional hazards regression. Results: 195 patients (40.2%) underwent a SLNB. SLNB was performed more commonly in younger, healthier patients with MCC located in the extremities or torso (Table). The results of 177 SLNBs were available; 60 (33.9%) were positive. SLNB-positive patients underwent completion dissection (n=15, 25%), completion dissection and nodal radiation (n=22, 36.7%), nodal radiation alone (n=18, 30%) or observation (n=5, 8.3%). Patients who did not undergo a SLNB underwent nodal radiation alone (n=40, 13.8%) or observation (n=250, 86.2%). The median follow-up was 2.7 years (range 0.2-14.4). The regional recurrence rate was 14.5% (n=17) among SLNB-negative versus 15% (n=9) among SLNB-positive patients. Among patients who did not undergo a SLNB, the regional recurrence rate was 25.2% (n=63) among those who underwent observation and 15% (n=6) among those who received nodal radiation alone. After propensity score matching, SLNB patients had a lower risk of regional recurrence (sHR 0.54 95% CI 0.34-0.86 p=0.01) and improved overall survival (HR 0.32 95% CI 0.23-0.45 p<0.01), but there was no difference in local recurrence (sHR 0.92 95% CI 0.50-1.69 p=0.79), distant recurrence (sHR 0.88 95% CI 0.52-1.49 p=0.63), or cancer-specific survival (HR 0.67 95% CI 0.31-1.45 p=0.31). Conclusions: SLNB is associated with a reduced risk of regional recurrence and improved overall survival. The role of SLNB in selecting patients for emerging therapies, such as immunotherapy, needs to be evaluated. [Table: see text]

The Role of Sentinel Lymph Node Biopsy in the Management of Merkel Cell Carcinoma: A Systematic Review and Meta-analysis

“…Several articles presented survival data for MCC, where head and neck tumors are compared with trunk or limb tumors; however, this was independent of SLNB and nodal status and therefore outside the scope of our review. 10,[22][23][24][25]27,29,[31][32][33]35,36 Conic et al highlighted that location of lesion had no bearing on overall survival, or node positivity, and Harounian et al presented comparative statistic demonstrating that head and neck location had no correlation with survival. 21,26 No articles presented granular outcome data for SLNB and no SLNB in head and neck tumors only; they were pooled in the results, with no extractable statistics.…”

“…[22][23][24][25][26][27][28]30,32,33,35 Only a single study 24 described which patients undergoing radiotherapy had positive SLNB. In those without SLNB, 808 patients from four studies 22,26,28,35 underwent regional radiotherapy without a prior SLNB. Finally, 225 patients across 11 studies [22][23][24][26][27][28][29][30][32][33][34] underwent completion lymphadenectomy, with 41 patients in two studies 26,34 undergoing lymphadenectomy without prior SLNB.…”

“…Ten studies gave details of recurrence of MCC within 5 years; Four of these compared patients who had had SLNB with those who had not, 22,26,31,34 with the remaining six only describing patients who underwent SLNB. [23][24][25]27,29,32,33 Recurrence within 5 years occurred in 23.3% (95% CI, 21.2%-25.5%) of patients undergoing SLNB.…”

“…10 Men made up 59.5% of the cohort; two studies (4393 patients) did not declare what proportion of the cohort were men. 22,35 The weighted mean age was 75.1 ± 2.12 years; four studies (7496 patients) did not describe the age of their cohort. 21,22,29,35 The disease stages of included patients within each study are outlined in Table 2.…”

“…All studies were either case series 10,[23][24][25]27,30,[32][33][34][35][36] or cohort studies. 21,22,26,28,29,31 The overall risk of bias assessment for included studies is represented in Figure 2 and Figure 3.…”