Is pelvic sentinel node biopsy necessary for lower extremity and trunk melanomas?

Pelvic sentinel lymph nodes have minimal impact on survival in melanoma patients

Background

Lower limb or trunk melanoma often presents with femoral and pelvic sentinel lymph nodes (SLNs). The benefits of harvesting pelvic lymph nodes remain controversial. In this retrospective study, the frequency and predictors of pelvic SLNs (PSLNs), and the impact of PSLNs on survival and staging was investigated.

Methods

Altogether 285 patients with cutaneous melanoma located in the lower limb or trunk underwent sentinel lymph node biopsy of the inguinal/iliac lymph node basin at Helsinki University Hospital from 2009–2013. Patient characteristics, detailed pathology reports and follow-up data were retrieved from hospital files. Subgroups of patients categorized by presence of PSLNs were compared for outcome parameters including progression-free survival, melanoma-specific survival and groin recurrence.

Results

Superficial femoral/inguinal SLNs were present in all patients and 199 (69.8 per cent) also had PSLNs removed. Median number of SLNs per patient was five and median number of PSLNs was two. Sixty-three patients (22.1 per cent) had metastases in their SLNs and seven (2.5 per cent) had metastases in PSLNs. A single patient had metastases solely in PSLNs, while superficial SLNs remained negative. Harvesting PSLNs or the number of PSLNs retrieved had no impact on progression-free survival or overall survival. The removal of PSLNs did not affect the risk of postoperative seroma or lymphoedema. The only predictor of positive PSLNs was radioactivity count equal to or more than that of the hottest superficial SLNs.

Conclusion

Pelvic SLNs have minimal clinical impact on the outcome of melanoma patients especially in cases with negative superficial femoral/inguinal SLNs. Removal of PSLNs should be considered when they are the most radioactive nodes or equal to the hottest superficial femoral/inguinal SLNs in lymphoscintigraphy or during surgery.

Preliminary results were presented in part at the International Sentinel Node Society Biennial Meeting, Tokyo, Japan, 11–13 October 2018.

Failure to identify sentinel lymph nodes for malignant melanoma - Outcome after over 10 years median follow up

BACKGROUND

Sentinel lymph node biopsy (SLNB) is routinely performed during surgery for malignant melanoma, using double mapping. Still, in some cases, a sentinel lymph node identified pre-operatively by lymphoscintigraphy is not identified during surgery. We hypothesized that disease specific survival would not be significantly impacted by intra-operative lymph node mapping (IOLM) failure.

METHODS

The patient population study included 1300 malignant melanomas operated on by a single surgical oncologist (H.G.) after sentinel lymph node scintigraphy. Patients were included in the analysis if intra-operative lymph node (IOLM) mapping failed.

RESULTS

Among 1300 patients who underwent surgery for malignant melanoma during the study period and after median follow up of >10 years, 33/36 lymphatic drainage basins with failed sentinel node identification were free of disease. Disease specific survival for the entire group of 33 patients with IOLM failure was 91.0%, which is comparable to previously published disease specific survival for all melanoma patients.

CONCLUSION

We conclude that failure to identify a pre-operatively marked sentinel lymph node by an experienced melanoma surgeon has, generally, no impact on disease specific survival, as demonstrated in this review of a series of surgical melanoma patients.

Routine retrieval of pelvic sentinel lymph nodes for melanoma rarely adds prognostic information or alters management

Pelvic sentinel lymph nodes (SLNs) are commonly identified during inguinal SLN biopsy for melanoma, but retrieval is not uniform among surgeons/centers. Few studies have assessed rates of micrometastases in pelvic versus superficial inguinal SLNs. Previous studies suggested that presence of pelvic SLNs was predicted by aggressive pathologic features and that their presence portended a worse prognosis. The objectives of this study were to examine presurgical predictors of pelvic SLNs among patients undergoing inguinal SLN biopsy, assess rates of micrometastases in superficial inguinal versus pelvic SLNs, and determine whether presence of pelvic SLNs was associated with long-term outcomes. Multivariable regression was used to assess presurgical factors associated with presence of pelvic SLNs. Rates of micrometastases in superficial inguinal versus pelvic SLNs in patients who had a pelvic SLN were compared with McNemar's test. Groin recurrence, disease-free survival (DFS), and disease-specific survival were analyzed by Kaplan-Meier method. A multivariable Cox model for DFS was performed. Pelvic SLNs were retrieved in 100/537 (18.6%) superficial inguinal SLN biopsies and no preoperative factors predicted their presence. In patients with a pelvic SLN, micrometastases were present in 3.0% of pelvic versus 34.0% of superficial inguinal SLN biopsies (P<0.001). There were no differences in groin recurrence, DFS, and disease-specific survival for patients with/without pelvic SLNs in univariate analyses (all P>0.2) or in the multivariable Cox model for DFS (hazard ratio: 1.1, 95% confidence interval: 0.6-2.1). In conclusion, pelvic SLNs harbor micrometastases less frequently than superficial inguinal SLNs do, suggesting that omission of pelvic SLN biopsy may be reasonable.