Histological immune response patterns in sentinel lymph nodes involved by metastatic melanoma and prognostic significance

Short- and long-term immunosuppressive effects of melanoma influence the prognostic value of the sentinel lymph node status

BACKGROUND

Presence of micrometastases in the sentinel lymph node (SLN) is currently used to assess prognosis of melanoma patients. The immunoactivity within the SLN is known to be influenced by the primary tumor (PT), which may in turn impact the SLNs' metastatic state.

AIM

We characterize the temporal dependence and underlying mechanisms of the immunological effects of the PT on the SLN.

METHODS

The prognostic value of SLN state as a function of PT removal time was evaluated. To put the results into a functional context, selected PTs and corresponding SLNs were analyzed for gene and protein expression patterns.

RESULTS

In a cohort of 202 patients with known distant metastasis and similar PT prognostic characteristics, SLNs removed before or within one week after the PT (IM-SLN) had a higher incidence of micrometastases than those removed at least one week after the PT (DEL-SLN). The immunoactivity in IM-SLN was found to be lower than in DEL-SLN. Specifically, in IM-SLNs, T helper 17 / regulatory T-cells were predominant, whereas in DEL-SLNs, cytotoxic γδT-cells were more frequent. The higher immune activity in DEL-SLNs was probably facilitated by CD209+ antigen-presenting cells. Indeed, in PT with high TGFβ expression CD209+ cells appear to be trapped and no increased immunoactivity was observed in DEL-SLN.

CONCLUSIONS

Presence of micrometastases in DEL-SLNs have a higher negative prognostic value as in IM-SLNs since they indicate not only a melanoma's propensity to metastasize, but possibly also its capacity to escape immune responses.

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.

Margins of Melanoma Excision and Modifications to Standards

Surgery with wide local excision is the mainstay of treatment for primary melanoma. Surgical margins differ depending on the depth of the primary lesion, subtype, and anatomic, cosmetic, or functional considerations. Adjuncts or alternative treatments to wide local excision are limited to specific patient populations and mainly experimental in nature.

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.

Molecular patterns of cancer colonisation in lymph nodes of breast cancer patients

Lymph node (LN) metastasis is an important prognostic parameter in breast carcinoma, a crucial site for tumour–immune cell interaction and a gateway for further dissemination of tumour cells to other metastatic sites. To gain insight into the underlying molecular changes from the pre-metastatic, via initial colonisation to the fully involved LN, we reviewed transcriptional research along the evolving microenvironment of LNs in human breast cancers patients. Gene expression studies were compiled and subjected to pathway-based analyses, with an emphasis on immune cell-related genes. Of 366 studies, 14 performed genome-wide gene expression comparisons and were divided into six clinical-biological scenarios capturing different stages of the metastatic pathway in the LN, as follows: metastatically involved LNs are compared to their patient-matched primary breast carcinomas (scenario 1) or the normal breast tissue (scenario 2). In scenario 3, uninvolved LNs were compared between LN-positive patients and LN-negative patients. Scenario 4 homed in on the residual uninvolved portion of involved LNs and compared it to the patient-matched uninvolved LNs. Scenario 5 contrasted uninvolved and involved LNs, whilst in scenario 6 involved (sentinel) LNs were assessed between patients with other either positive or negative LNs (non-sentinel).

Gene lists from these chronological steps of LN metastasis indicated that gene patterns reflecting deficiencies in dendritic cells and hyper-proliferation of B cells parallel to tumour promoting pathways, including cell adhesion, extracellular matrix remodelling, cell motility and DNA repair, play key roles in the changing microenvironment of a pro-metastatic to a metastatically involved LN. Similarities between uninvolved LNs and the residual uninvolved portion of involved LNs hinted that LN alterations expose systemic tumour-related immune responses in breast cancer patients. Despite the diverse settings, gene expression patterns at different stages of metastatic colonisation in LNs were recognised and may provide potential avenues for clinical interventions to counteract disease progression for breast cancer patients.

Lymph Node Cellular Dynamics in Cancer and HIV: What Can We Learn for the Follicular CD4 (Tfh) Cells?

Lymph nodes (LNs) are central in the generation of adaptive immune responses. Follicular helper CD4 T (Tfh) cells, a highly differentiated CD4 population, provide critical help for the development of antigen-specific B cell responses within the germinal center. Throughout the past decade, numerous studies have revealed the important role of Tfh cells in Human Immunodeficiency Virus (HIV) pathogenesis as well as in the development of neutralizing antibodies post-infection and post-vaccination. It has also been established that tumors influence various immune cell subsets not only in their proximity, but also in draining lymph nodes. The role of local or tumor associated lymph node Tfh cells in disease progression is emerging. Comparative studies of Tfh cells in chronic infections and cancer could therefore provide novel information with regards to their differentiation plasticity and to the mechanisms regulating their development.