Expression Of Nm23 And E-cadherin In Stage Ⅰ Non-small Cell Lung Cancer, And Their Relationship With Lymph Node Micrometastasis And Prognosis

BackgroundLung cancer has become one of the most important malignant diseases in China. Yet, the treatment for this disease is far from satisfactory; around 25% of patients die within 5 years due to recurrence or metastasis even for "curable" stage I disease. Although the current pathological staging system is consistent with patients' prognosis as a whole, more than often, stageⅠpatients can have different results. It is possible that stageⅠdiseases already have micrometastasis (or occult metastasis) that cannot be ascertained by traditional pathological means. At present, routine clinical examinations are not able to find a better way of estimating patients'prognosis under the present lung cancer staging system, which prompts us to make modifications from the aspect of micrometastasis.Methods to detect micrometastasis include:serial section, immunohistochemistry, flow cytometry, reverse transcription polymerase chain reaction (RT-PCR), etc. The RT-PCR technique is gaining popularity for its high sensitivity.There are four kinks of molecular markers widely used in the detection of lung cancer micrometastasis:tissue specific proteins, tumor specific antigens, oncogenes or cancer suppressor genes, and tissue specific genes. LUNX, a human lung tissue specific gene, is a promising new marker for the detection of micrometastasis.Changes may happen to the expression of some metastasis-related genes before metastasis is detectable, probably during the early stage of micrometastasis. To explore the relationship between the expression of these genes and micrometastasis will help to determine molecular staging with higher accuracy, which, in turn, makes multi-disciplinary therapy for early stage lung cancer possible. PurposesTo investigate the detection of lymph node micrometastasis in stage I non-small cell lung cancers (NSCLC) using LUNX mRNA as a marker based on RT-PCR and its relationship with the patho-clinical features and prognosis. To discuss the feasibility of detecting lymph node micrometastasis with this technique.MethodsTo collect stageⅠNSCLC undergoing radical surgical resection. To examine the expression of cytokeratins (CKs) by means of immuno-histochemistry, then recheck under pathology in order to eliminate those with metastasis but neglected. Forty cases of stage pⅠdiseases were finally thus collected. Ten cases of benign lung diseases undergoing surgical resection were also collected for reference.All patients underwent curative lobectomy, excluding pneumonectomy and palliative resection. Curative lobectomy included systemic lymph node resection, which meant at least 6 mediastinal lymph nodes from 3 stations were resected.The expression of LUNX mRNA in each station of lymph nodes were examined by means of RT-PCR. LUNX mRNA was then used as a marker of lymph node micrometastasis. Analyses of relationship between lymph node micrometastasis and the pathoclinical features, overall survival and disease free survival were then carried out.ResultsAll lymph nodes with positive CKs expression were found to have metastasis during pathological recheck.The expression of LUNX mRNA:none was positive for all ten lymph nodes from benign diseases. All 40 lung cancer tissues showed positive expression,14.6% of lymph nodes and 11.1% of mediastinal lymph nodes showed positive expression. In 16 patients (40%), at least one station of lymph nodes showed positive expression, so that the LUNX stage was upgraded. In LUNX staging, there were 13 stage la,11 stageⅠb,3 stageⅡa,6 stageⅡb and 7 stageⅢa cases. Lymph nodes micrometastasis was not correlated with gender, age, pathological stage, type of cancer, number of lymph nodes and mediastinal lymph nodes resected (P> 0.05).Survival affecting factors included:LUNX stage (P< 0.01), mediastinal lymph nodes micrometastasis (P< 0.01), number of lymph nodes and mediastinal lymph nodes resected (P< 0.05), pathological differentiation (P< 0.05). Those with mediastinal lymph nodes micrometastasis had a 30.3 folds higher risk of death than those without (P＜0.01). Those who had 6 stations of mediastinal lymph nodes resected had a 2.125 folds higher risk of death than those only had 3 stations removed.Factors affecting disease free survival included:LUNX stage (P< 0.01), lymph nodes micrometastasis (P< 0.05), mediastinal lymph nodes micrometastasis (P< 0.01), number of lymph nodes and mediastinal lymph nodes resected (P< 0.01), pathological differentiation (P＜0.05). Those with mediastinal lymph nodes micrometastasis had a 19.6 folds higher risk of recurrence than those without (P<0.01).ConclusionExamination of the expression of cytokeratins (CKs) can not find real micrometastasis, but only those with metastasis but neglected under routine pathological examination.The expression of LUNX mRNA in lymph nodes is related to overall survival and disease free survival, and is a reflection of lymph node micrometastasis. The subgroup of stage pⅠpatients with high risks can be thus found. This technique is helpful in restaging patients more accurately. Survival can be improved if interference is applied in early stage. PurposesTo examine the expression of nm23 and E-cadherin in stage pⅠlung cancer tissues by means of immuno-histochemistry. To discuss their relationship with lymph node micrometastasis and prognosis.MethodsFor methods of patient selection, surgical techniques and sample collection, refer to part one.To examine the expression of nm23 and E-cadherin in lung cancer tissues by means of immuno-histochemistry.ResultsThere was no significant difference in nm23 expression between lung cancer and normal lung tissues (P> 0.05). The positive rate of E-cadherin expression in lung cancer was significantly higher than in normal lung tissues (P< 0.01).Nm23 and E-cadherin were differently expressed among LUNX stages (P< 0.01), but not among pathological stages (P> 0.05).Those with a lower expression rate of nm23 or E-cadherin had a higher rate of lymph node micrometastasis (P< 0.05 and P< 0.01).Those with a lower expression rate of nm23 had a shorter overall survival time (P < 0.05), but no significant change in disease free survival (P> 0.05). Those with a lower expression rate of E-cadherin had a shorter disease free survival time (P< 0.05), but no significant change in overall survival (P> 0.05).Cox Regression risk ratio analysis showed the expression level of nm23 in lung cancer tissues is an independent risk factor for overall survival, those with a lower expression rate had a 13.31 folds higher risk of death (P< 0.05).ConclusionThe down-regulation of nm23 and E-cadherin expression foreshow a higher risk of lymph node micrometastasis. Those with a lower expression rate of nm23 have a shorter overall survival time; nm23 expression is an independent risk factor for overall survival. By evaluating nm23 and E-cadherin expression in lung cancer tissues, the risk of lymph node micrometastasis can be foreshown, hence a more accurate molecular staging can be established to find the high risk subgroup in stage pⅠpatients.