The Premetastatic Lymph Node Niche in Gynecologic Cancer

It has been suggested that a primary tumor can "prepare" the draining of lymph nodes to "better accommodate" future metastatic cells, thus implying the presence of a premetastatic lymph node niche. However, this phenomenon remains unclear in gynecological cancers. The aim of this study was to evaluate lymph-node draining in gynecological cancers for premetastatic niche factors, such as myeloid-derived suppressor cells (MDSCs), immunosuppressive macrophages, cytotoxic T cells, immuno-modulatory molecules, and factors of the extracellular matrix. This is a monocentric retrospective study of patients who underwent lymph-node excision during their gynecological-cancer treatment. In all, 63 non-metastatic pelvic or inguinal lymph nodes, 25 non-metastatic para-aortic lymph nodes, 13 metastatic lymph nodes, and 21 non-cancer-associated lymph nodes (normal controls) were compared for the immunohistochemical presence of CD8 cytotoxic T cells, CD163 M2 macrophages, S100A8/A9 MDSCs, PD-L1+ immune cells, and tenascin-C, which is a matrix remodeling factor. PD-L1-positive immune cells were significantly higher in the control group, in comparison to the regional and distant cancer-draining lymph nodes. Tenascin-C was higher in metastatic lymph nodes than in both non-metastatic nodes and control lymph nodes. Vulvar cancer-draining lymph nodes showed higher PD-L1 values than endometrial cancer and cervical cancer-draining lymph nodes. Endometrial cancer-draining nodes had higher CD163 values and lower CD8 values, compared to vulvar cancer-draining nodes. Regarding regional draining nodes in low- and high-grade endometrial tumors, the former showed lower S100A8/A9 and CD163 values. Gynecological cancer-draining lymph nodes are generally immunocompetent, but vulvar cancer draining nodes, as well as high-grade endometrial cancer draining nodes, are more susceptible to harboring premetastatic niche factors.