Mechanism of lymph node metastases: current concepts

[Invasion and metastasis mechanism of human papillomavirus in head and neck squamous cell carcinomas]

Human papillomavirus (HPV) is a major causative agent of head and neck squamous cell carcinomas (HNSCC). Over the past several decades, an increasing number of studies established the strong association of HPV with the invasion and metastasis of HNSCC. In the present study, we reviewed the gene mutations in HPV-associated HNSCC and the unique mechanism of E6- and E7-mediated carcinogenesis via interactions with an array of cellular elements. We further discussed the progress in the mechanisms of invasion and metastasis; these mechanisms include non-coding RNAs, deregulating cellular energetics, tumor microenvironment, cancer stem cells, angiogenesis, and lymphangiogenesis.

Recent Developments on the Significance and Pathogenesis of Lymph Node Involvement in Ovarian Serous Tumors of Low Malignant Potential (Borderline Tumors)

In approximately 27% of patients that were surgically staged for ovarian serous borderline tumors (ovarian serous tumors of low malignant potential), regional lymph nodes, most commonly the pelvic and paraaortic groups, display morphologically similar epithelial clusters. Lymph nodes above the diaphragm may also be involved. Lymph node involvement does not adversely impact the overall survival of patients with ovarian serous borderline tumors, but there is controversy as to whether this finding is associated with a decrease in recurrence-free survival. Nodular aggregates of epithelium greater than 1 mm in maximum dimension, as compared with all other patterns of nodal involvement, have been associated with reduced recurrence-free survival. The lymph nodes may also be the site of recurrence and/or progression to carcinoma of an ovarian serous borderline tumor. Recent molecular and morphologic data suggest that although most nodal implants are indeed metastatic from their synchronous ovarian neoplasms, a small subset arise de novo from nodal endosalpingiosis. The precise mechanistic basis for how these noninvasive neoplasms achieve nodal metastases is unclear. However, because most patients with nodal metastases also have peritoneal implants, tumors that are ovary-confined and without ovarian surface involvement are rarely associated with nodal involvement, microinvasive borderline tumors frequently display lymphatic vessel involvement yet show a remarkably low frequency of nodal involvement, in conjunction with the recent finding that node-positive and node-negative tumors display no significant differences in lymphatic vessel density, suggest that the route of spread to lymph nodes in most cases is via the peritoneal and not tumoral lymphatics.

A comparative analysis of lymphatic vessel density in ovarian serous tumors of low malignant potential (borderline tumors) with and without lymph node involvement

Lymph node involvement is seen in approximately one quarter of women with surgically staged ovarian serous tumors of low malignant potential (serous borderline tumors), and this finding apparently does not adversely impact their overall survival. To help illuminate some of the pathomechanisms underlying this novel phenomenon, in which a largely noninvasive epithelial neoplasm is able to exit its primary site and be transported to lymph nodes with such a substantial frequency, we investigated whether significant differences in lymphatic vessel density exist between ovarian serous borderline tumors that show lymph node involvement and those that do not. The lymphatic vessel density of 13 conventional ovarian serous borderline tumors (i.e. tumors without stromal microinvasion, micropapillary/cribriform areas, or invasive implants) with at least 1 positive lymph node (study group) was compared with the lymphatic vessel density of an age- and disease extent-matched control group of 13 similarly selected lymph node-negative ovarian serous borderline tumors. Lymphatic vessel density was determined by counting the total number of vascular spaces immunohistochemically stained by the lymphatic endothelium marker D2-40 in 5 consecutive microscopic fields (x20 objective, field area of 1 microscopic field, 0.95 mm) in the most vessel-dense areas and calculating the average value per microscopic field. The peritumoral lymphatic vessel density was significantly higher than the intratumoral lymphatic vessel density in both groups. However, no statistically significant differences were found between the study and control groups regarding intratumoral lymphatic vessel density (8.0 vs. 7.61; P=0.77), peritumoral lymphatic vessel density (20.33 vs. 21.0; P=0.79), or combined, that is, peritumoral plus intratumoral lymphatic vessel density (27.81 vs. 28.62; P=0.83). Our findings, in conjunction with others in the medical literature, do not support a role for tumor lymphatics in nodal metastasis in this neoplasm. We discuss the possibility that nodal deposits may represent metastatic disease from secondary tumor implants.

Prognostic significance of nm23-H1 expression in oral squamous cell carcinoma

Recent studies indicated nm23-H1 played a role in cancer progression. Therefore, we investigated clinical significance of nm23-H1 expression in oral squamous cell carcinoma (OSCC). In total, 86 OSCC specimens were immunohistochemically stained with nm23-H1-specific monoclonal antibodies. Immunohistochemical staining of nm23-H1 was confirmed by immunoblotting. The relations between nm23-H1 expression and clinicopathologic variables were evaluated by chi(2) analysis. As increased size of primary tumour could escalate metastatic potential and the data of patients at the late T stage might confound statistical analyses, we thus paid special attention to 54 patients at the early T stage of OSCC. Statistical difference of survival was compared by a log-rank test. Immunohistochemically, nm23-H1 expression was detected in 48.8% (42 out of 86) of tumorous specimens. It positively correlated with larger primary tumour size (P=0.03) and inversely with cigarette-smoking habit (P=0.042). In patients at the early T stage, decreased nm23 expression was associated with increased incidence of lymph node metastasis (P=0.004) and indicated poor survival (P=0.014). Tumour nm23-H1 expression is a prognostic factor for predicting better survival in OSCC patients at the early T stage, which may reflect antimetastatic potential of nm23. Therefore, modulation of nm23-H1 expression in cancer cells can provide a novel possibility of improving therapeutic strategy at this stage. In addition, our results further indicated cigarette smoking could aggravate the extent of nm23-H1 expression and possibly disease progression of OSCC patients.

Down-Regulated Expression of Cytokeratin 18 Promotes Progression of Human Breast Cancer

PURPOSE

Cytokeratins (CKs) have been recognized for >20 years as structural marker proteins specific for epithelial cells. Recent expression profiling analyses indicate, however, that CK down-regulation may occur in breast cancer.

EXPERIMENTAL DESIGN

Here we evaluated the expression pattern of CK18 by immunohistochemical analysis of primary breast carcinomas (n = 1458) spotted on a high-density tissue microarray. The findings were correlated to histopathological risk factors and clinical outcome.

RESULTS

Down-regulation of CK18 (as compared to normal breast tissue) was observed in 25.4% of the tumors with a lower rate in lobular carcinomas (17.0%) than in ductal carcinomas (25.4%) or other histological entities (32.5%). CK down-regulation was significantly correlated to advanced tumor stage and high grade but not to axillary lymph node status. Kaplan-Meier survival analysis revealed CK18 as a prognostic indicator of overall survival (P = 0.015) and cancer-specific survival (P = 0.005).

CONCLUSIONS

Down-regulation of the luminal CK18 is not rare and a clinically relevant event in breast cancer. This finding has important implications for the use of CK18 as epithelial tumor marker. The correlations with clinical follow-up suggest that CK18 might suppress tumor progression.