Selective Sentinel Lymph Node Dissection in Lower Extremity Melanoma
Suzette G. Miranda, MD1, Rui Li, PhD2, Brian Parrett, MD3, Grant Lee, MD4, Suresh Thumala, BS5, Tiffany Chang, .4, Niloofar Fadaki, MD5, Servando Cardona-Huerta, M.D.5, Shih-Tsung Cheng, M.D.5, James Cleaver, M.D.4, Mohammed Kashani-Sabet, MD5, Stanley Leong, MD6.
1Buncke Clinic and University of California San Francisco, San Francisco, CA, USA, 2Novartis Oncology Biostatistics, San Francisco, CA, USA, 3Buncke Clinic, San Francisco, CA, USA, 4University of California San Francisco, San Francisco, CA, USA, 5California Pacific Medical Center, San Francisco, CA, USA, 6California Pacific Medical Center and University of California San Francisco, San Francisco, CA, USA.
There is debate as to which nodes should be removed during selective sentinel lymph node dissection (SLND) for lower extremity melanoma (LEM). The purpose of this study is to focus specifically on pertinent lymphatic drainage patterns in LEM and whether harvesting a sentinel lymph node (SLN) in deep inguinal in addition to a superficial inguinal basin influences clinical management.
A retrospective outcomes review of LEM patients with excision of primary melanoma and selective SLND of LEM lymph node basins from 1995-2010. Main outcome measures included lymphatic drainage basins, SLN positivity, disease free and overall survival.
Of 499 patients with LEM having selective SLND, 356 had melanoma below the knee and 143 above the knee. For LEM below the knee, the positive SLN rate was 23% for superficial inguinal (SI), 0% for deep inguinal (DI), and 50% for popliteal basins. For LEM above the knee, the positive SLN rate was 21% for SI, 33% for DI basins and 0% for popliteal basins (Table 1). The flowchart demonstrated in Figure 1 illustrates simultaneous drainage to both SI and DI basins on lymphoscintigraphy. Eighty-six patients had drainage into both basins. 74 patients had negative SI nodes seen on pathology and if SI SLNs were negative, DI SLNs were negative too.12 patients had positive SI and/or DI SLN and on pathology, 9 were positive in the SI basin and 3 patients positive in both basins. Figure 2 shows Kaplan Meir curves confirming that patients with positive SLNs have a significantly reduced disease free survival when compared to patients with negative SLNs. Patients who underwent DI and SI selective SLN dissection had a significant difference (p value < 0.001) in time of operation when compared to only SI selective SLN.
A difference was noted in patterns of SLN drainage from LEM below and above the knee. The more interesting finding was when there was simultaneous SLN drainage seen in both SI and DI basins. There was never any positive DI nodes when SI nodes were negative in 74 patients. However, in 12 patients with both drainages, 3 had positive SLNs in both basins. We conclude there is no benefit in performing a DI selective SLN dissection initially when preoperative lymphoscintigraphy shows drainage to both basins. This would reduce the operating time, time under anesthesia, and the morbidity associated with increased operative time and surgery. However, if SLNs are found to be positive on pathology in patients with simultaneous drainage, then a completion combined ilioinguinal lymph node dissection may be recommended.
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