Prognostic significance of drainage to pelvic nodes at sentinel lymph node mapping in patients with extremity melanoma

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.

Robotic-Assisted Pelvic Lymphadenectomy for Metastatic Melanoma Results in Durable Oncologic Outcomes

BACKGROUND

Robotic pelvic lymphadenectomy (rPLND) has been demonstrated to be a safe and effective minimally invasive approach for patients with metastatic melanoma to the iliac nodes. However, the long-term oncologic benefit of this procedure remains poorly defined.

METHODS

A single-institutional study comparing perioperative outcomes and survival [recurrence-free (RFS) and overall survival (OS)] between rPLND and open PLND (oPLND) for metastatic melanoma was conducted.

RESULTS

From 2006 to 2018, a total of 63 PLND cases were identified: 22 rPLND and 41 oPLND. Evidence of isolated pelvic metastasis was the most common indication for PLND in both groups (rPLND: 64%, oPLND: 85%). There was no difference in median pelvic lymph node yield (11 vs. 9 nodes, p = 0.65). Neither treatment group experienced a Clavien-Dindo complication ≥ 3. rPLND was associated with a shorter length of stay compared with oPLND (2 vs. 4 days, p < 0.001). With a median follow-up of 37 months, there was no difference in RFS (14.4 vs. 9.6 months, p = 0.47) and OS (43 vs. 50 months, p = 0.58) between rPLND and oPLND, respectively. In basin recurrence was low with 1 (4.5%) and 3 (7.3%) patients in the rPLND and oPLND cohorts, respectively, experiencing an event (p = 0.9).

CONCLUSIONS

rPLND for metastatic melanoma is a safe, minimally invasive treatment strategy that appears to result in similar intermediate term recurrence and survival rates as oPLND but shorter hospital stays.

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.

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

OBJECTIVE

There is currently no consensus regarding how to address pelvic sentinel lymph nodes (PSLNs) in melanoma. Thus, our objectives were to identify the incidence and clinical impact of PSLNs.

METHODS

Retrospective review of a prospectively collected multi-institutional melanoma database.

RESULTS

Of 2476 cases of lower extremity and trunk melanomas, 227 (9%) drained to PSLNs (181 to both PSLNs and superficial (inguinal or femoral) sentinel lymph nodes (SSLN) and 46 to PSLNs alone). Seventeen (7.5%) of 227 PSLN cases were positive for nodal metastasis, 8 of which drained to PSLNs only while 9 drained to both PSLNs and SSLNs. Complication rates between PSLN and SSLN biopsy were similar (15% vs. 14% respectively). In 181 cases with drainage to both SSLNs and PSLNs, PSLN biopsy upstaged one patient (0.6%), and completion dissection based on a positive PSLN did not upstage any.

CONCLUSIONS

PSLN biopsy is safe, however in the setting of negative SSLNs there is minimal clinical impact. We therefore recommend PSLN biopsy when the SSLNs are positive or when the tumor drains to PSLNs alone.

Fluorescence tomographic imaging of sentinel lymph node using near-infrared emitting bioreducible dextran nanogels

Sentinel lymph node (SLN) mapping is a critical procedure for SLN biopsy and its diagnosis as tumor metastasis in clinical practice. However, SLN mapping agents used in the clinic frequently cause side effects and complications in the patients. Here, we report the development of a near-infrared (NIR) emitting polymeric nanogel with hydrodynamic diameter of ~28 nm – which is the optimal size for SLN uptake – for noninvasive fluorescence mapping of SLN in a mouse. This polymeric nanogel was obtained by coupling Cy7, an NIR dye, to the self-assembled nanogel from disulfide-linked dextran-deoxycholic acid conjugate with the dextran of 10 kDa, denoted as Dex–Cy7. Fluorescence imaging analysis showed that Dex–Cy7 nanogels had an enhanced photostability when compared to Cy7 alone. After intradermal injection of Dex–Cy7 nanogel into the front paw of a mouse, the nanogels were able to migrate into the mouse’s axillary lymph node, exhibiting longer retention time and higher fluorescence intensity in the node when compared to Cy7 alone. An immunohistofluorescence assay revealed that the nanogels were localized in the central region of lymph node and that the uptake was largely by the macrophages. In vitro and in vivo toxicity results indicated that the dextran-based nanogels were of low cytotoxicity at a polymer concentration up to 1,000 μg/mL and harmless to normal liver and kidney organs in mice at an intravenous dose of 1.25 mg/kg. The results of this study suggest that NIR-emitting polymeric nanogels based on bioreducible dextran-deoxycholic acid conjugates show high potential as fluorescence nanoprobes for safe and noninvasive SLN mapping.