Sentinel Lymph Node Biopsy: Indications and Technique

Review on Lymph Node Metastases, Sentinel Lymph Node Biopsy, and Lymphadenectomy in Sarcoma

Soft tissue sarcomas (STS) originating from connective tissue rarely affect the lymph nodes. However, involvement of lymph nodes in STS is an important aspect of prognosis and treatment. Currently, there is no consensus on the diagnosis and management of lymph node metastases in STS. The key risk factor for nodal involvement is the histological subtype of sarcoma. Radiological and pathological evaluation seems to be the most effective method of assessing lymph nodes in these neoplasms. Thus, sentinel lymph node biopsy (SLNB), which has been shown to be valuable in the management of melanoma or breast cancer, may also be a beneficial diagnostic option in some high-risk STS subtypes. This review summarizes data on the risk factors and clinical characteristics of lymph node involvement in STS. Possible management and therapeutic options are also discussed.

Is skipped nodal metastasis a phenomenon of cutaneous melanoma?

BACKGROUND AND METHODS

Skipped nodal metastasis (SNM) is a recognized phenomenon of visceral cancers when metastases bypass the regional basin and skip to a distant nodal basin without evidence of distant metastases. Its occurrence is undocumented in cutaneous melanoma patients but of potential prognostic significance. We therefore assessed the frequency of SNM in a large series of patients with limb melanomas.

PATIENTS AND METHODS

We studied melanoma patients attending a tertiary oncology hospital in northwest England using two approaches. First, we systematically searched medical records of an unselected patient sample treated 2002-2015, and second, we studied lymphoscintigrams of all patients with limb melanoma who underwent sentinel node biopsy 2008-2019.

RESULTS

Of 672 melanoma patients whose clinical records were examined, 16 had regional nodal metastases without apparent visceral spread and one appeared to have SNM but further scans were uncovered that showed concurrent pulmonary metastases. Of 667 limb melanoma patients with lymphoscintigrams, 7 showed dual lymphatic drainage patterns to distal as well as regional nodal basins, but none had micro-metastases solely in the distant basin.

CONCLUSION

Occurrence of SNM in cutaneous melanoma is highly unlikely.

Stage IIIa Melanoma and Impact of Multiple Positive Lymph Nodes on Survival

BACKGROUND

For patients with cutaneous melanoma, having >1 positive lymph node (LN) is associated with worse survival. We hypothesized that for stage IIIA patients, N2a disease (2 to 3 positive LN) would be associated with a worse prognosis compared to those with N1a disease (1 positive LN).

STUDY DESIGN

Stage IIIA melanoma patients in the NCDB Participant User File from 2010 to 2016 were analyzed. Overall survival (OS) between N1a and N2a patients was compared. Subgroup analyses were made between patients undergoing sentinel lymph node (SLN) biopsy alone and those undergoing subsequent completion lymph node dissection (CLND). A separate post hoc analysis of T2a patients undergoing SLN biopsy and CLND from a prospective multicenter randomized clinical trial was performed to validate the findings.

RESULTS

Records of 2,305 IIIA patients were evaluated. In an adjusted survival model, N2a disease was an independent risk factor for worse OS (hazard ratio [HR] 1.56, p = 0.0052). In the subgroup analysis, there was no difference in OS between N1a and N2a disease for patients who underwent SLN biopsy without CLND (p = 0.59), but there was a significant difference in OS for patients who underwent SLN biopsy plus CLND (p = 0.0009). The separate clinical trial database confirmed that for patients with SLN-only disease, there was no difference in OS between N1a and N2a disease.

CONCLUSIONS

For stage IIIA melanoma patients, the distribution of micrometastatic lymph node disease (SLN or non-SLN), rather than the absolute number of SLNs, should be considered when individualizing adjuvant therapy recommendations.