Lymph node ratio as a prognostic factor in melanoma: results from European Organization for Research and Treatment of Cancer 18871, 18952, and 18991 studies

Investigation of prognostic factors for non-sentinel lymph node metastasis in patients undergoing sentinel lymph node biopsy for cutaneous malignant melanoma: Experience from a reference centre in Turkey

BACKGROUND

In the light of the results of recent randomised controlled trials regarding the role of nodal observation and completion lymph node dissection (CLND), studies from different populations are needed. The aim of our study was to present our experience with sentinel lymph node biopsy (SLNB) and CLND and the clinical and histopathological factors associated with a positive non-sentinel node.

METHODS

In this single-centre, retrospective study, we reviewed histopathological reports of patients with primary cutaneous melanoma who underwent SLNB and CLND over a period of 7 years. The primary outcomes were the positivity rates of SLNBs and CLNDs. Secondary outcomes were metastatic tumour burden in positive sentinel nodes and presence of perinodal invasion.

RESULTS

Among the 110 participants who underwent SLNB (53 females, 57 males), the mean Breslow thickness of the primary tumour was 4.1 (0.3-41) mm. Ulceration appeared in 62.7% of lesions. The SLNBs were positive in 38 patients (34.5%), with 35 (92.1%) undergoing CLND, among which 9 (25.7%) showed metaNBstasis. Positive SLNB was linked to a higher Breslow thickness (p = 0.022), whereas CLND results lacked such an association (p = 0.76). Perinodal invasion (p = 0.006) and sentinel lymph node metastasis exceeding 1 mm (p = 0.017) was associated with a higher probability of non-sentinel node metastasis.

CONCLUSION

To adapt the results of the new cohort study on SLNB and melanoma to different populations, studies with different patient groups highlighting the problems and suggested solutions are needed.

Proposed Quality Performance Indicators (QPI's) for axillary lymphadenectomy in metastatic cutaneous melanoma

INTRODUCTION

Axillary lymph node clearance (ALNC) continues to play a central role in the management of melanoma. However, what defines an adequate lymphadenectomy remains unclear. We aimed to propose Quality Performance Indicators (QPIs) for ALNC and to determine if the number of lymph nodes (LNs) removed impacts survival.

METHODS

We reviewed patients who underwent ALNC for melanoma at the Waitemata District Health Board and Melanoma Unit between February 2005 and October 2019, performed by two surgeons with standardized technique and surveillance.

RESULTS

105 patients with stage III melanoma were included, of which 73 had clinically evident disease and 32 had clinically occult disease. The mean total number of LNs excised was 29 (SD 10.90, range 10-76). On multivariate analysis, lymph node ratio (HR 4.48, 95% CI 1.55-12.93, p = 0.006), extracapsular spread (HR 2.53, 95% CI 1.06-6.05, p = 0.036) and distant recurrence (HR 11.24, 95% CI 3.79-33.31, p < 0.001) were significant predictors of mortality. The number of LNs removed did not predict survival outcomes, while the lymph node ratio did significantly predict survival outcomes. The regional recurrence rate was 3.8%.

DISCUSSION

We propose that QPIs for ALNC in melanoma include a 90th percentile LN yield of greater than 15, a mean LN yield of 20, a regional recurrence rate of less than 10%, and an overall complication rate of less than 50%.

CONCLUSION

The establishment of QPIs can help ensure that surgical oncology patients receive the highest quality of care.

Pathology of Melanoma

Melanoma is an aggressive malignancy arising from melanocytes in the skin and rarely in extracutaneous sites. The understanding of pathology of melanoma has evolved over the years, with the initial classifications based on the clinical and microscopic features to the current use of immunohistochemistry and genetic sequencing. The depth of invasion and lymph node metastasis are still the most important prognostic features of melanoma. Other important prognostic features include ulceration, lymphovascular invasion, mitosis, and tumor-infiltrating lymphocytes. This article reviews the pathology of melanoma and its precursor lesions, along with the recent advances in pathologic diagnosis of melanoma.