The Relation Between Micrometastases In Lymph Nodes Of Gastric Cancer And It's Biological Behavior

The gastric cancer is one of our country most common malignant tumors of the alimentary canal. Also it is the malignant tumor with the highest mortality rate of all the cancers in cities. Its so high mortality rate is mainly because of the high probability of its metastasis and relapse. The metastasis and relapse of the malignant tumor are important factors that affect the tumor patient prognosis. The main way of the metastasis of the gastric cancer is through the lymph node shift, and the micrometastasis of the gastric cancer lymph node is probably the main reason to cause lymph node shift. Since the discovery of cancer cell in the peripheral blood, the concept of micrometastasis is put forward and moreover thought much of gradually by the general scholars. After many years'research on micrometastasis, many scholars think that the clinical metastasis is evolved from the micrometastasis. Although not all micrometastasis will evolve into clinical metastasis, since the process of the evolvement is closely related to the autoimmunity system of the patient, and the type of the cancer cell, etc al., however micrometastasis is still very important in judging the biological behavior of the tumor in clinical diagnosis. The biology behavior of the gastric cancer is referred to a series of indexes, which indicate the nature of the gastric cancer nature or its malignant degree. Thereforeto make clear the relationship between the micrometastasis of the gastric cancer lymph node and its biological behavior is crucial to the clinical stage appraisal and the formulation of the therapeutic regimen for the gastric cancer patient. Some scholars even think that the micrometastasis should become an independent factor to the prognosis appraisal of the tumor patient.The lymph node micrometastasis refers to the cancer metastasis stove that cannot be discovered by histology inspection on a traditional lymph node section. Since the number of the micrometastasized tumor cells is so small that there is no clinical manifestation, it is difficult to be discovered by the conventional inspection method such as the blood examination, the phantom study, and the ordinary pathology inspection. Hence clinician neglects it easily. At present the methods to determine the lymph node micrometastasis include the continual pathology slicing, the immunity group reduction and the counter duplication polymerase chain reaction (RT-PCR). The first one is given up gradually by people, because it is extremely tedious with high workload, time-consuming and hard to work, additionally it cannot determine the micrometastases of few or single tumor cell. The latter two are at present the main methods to examine the lymph node micrometastases situation. In particular along with the gene technology progress as well as the molecular biology development in recent years, it is gradually agreed by the generalscholars to take the RT-PCR method to examine the lymph node micrometastases. Presently after the appearance of the semi- quantitative and the real-time fluorescence quota RT-PCR method, more precise and more effective results were obtained to examine the lymph node micrometastases with them. At the same time it also reduce the false positive rate. But these two methods have high requirement for the equipment and the operator's technique, and hence they cannot be widely used for the moment. However, with the innovation and maturation of different techniques, the micrometastasis examination will become a conventional method in analyzing the patient condition clinically.The purpose of the present experiment is to determine the lymph node micrometastasis of gastric cancer patients by molecular biology method (semi-quantitative RT-PCR), and correlate the results with the biological behaviors of the gastric cancer to discuss their relationship.The experiment is performed on 83 gastric cancer patients according to the pathological diagnosis and by the D3 thorough therapy in the general surgery department of the first clinical hospital of Jilin University from March to October of 2006. 59 of them are male and 24 are female, their ages are between 42 and 81 with average of 68 years old. No chemotherapy or radiotherapy had been performed on these patients before operation. The negative control group is composed of 5 patients who did subtotal gastrectomy ongastrohelcoma and 3 patients who did subtotal gastrectomy on gastric interstitialoma. 76 lymph node samples around the stomach were taken from the negative control group, 141 lymph node samples around the stomach were taken from the positive control group of 31 gastric cancer patients with metastasis according to the ordinary pathological diagnosis. The lymph node samples of the gastric cancer patients without metastasis according to the ordinary pathological diagnosis were taken from the second and third stations of the swollen lymph node in D3 thorough therapy. Half of the lymph node samples were examined by the ordinary pathological diagnosis, and the other half samples were measured by semi-quantitative RT-PCR and marked with CK18 on 245 lymph node samples of 83 gastric cancer patients. These lymph node samples were taken on the second and third stations of the lymph node without metastasis according to the ordinary pathological diagnosis. The PCR products were analyzed by 1% agarose gel electrophoresis (dyed with Ethidium Bromide) and taken picture under UV light. Glyko bandscan system was used to determine the total gray intensity of the CK18mRNA andβ-actin bands in the samples and their ratio was calculated accordingly. The results were expressed by mean value deviation (Χ2), and were analyzed by correlating them with the biological behaviors of the patients'tumors.It was found that 1. In the investigation class, the positiveexpression of CK18mRNA in 125 (51%, 125/245) lymph nodes come from 51 (61.4%, 51/83) patients. There are 31 patients in theses 51 patients'distant (second or third) station lymph nodes take on a positive expression. The else 20 patients only have the positive expression of the first station lymph nodes. 2. All the positive class lymph nodes have positive expression. All the negative class lymph nodes have negative expression. 3. Gastric cancer with lymph nodes micrometastasis have a more malignant tendency biological behavior. Such as bad histological typing, ill pathological typing, more tumors of Borrmann III or IV.Conclusion: 1. Detecting lymph nodes micrometastasis with semiquantitative RT-PCR method and marked with CK18 mRNA can get a sensitive and accurate result. 2. If carcinoma has a positive expression of its lymph nodes, its feature of biological behavior will be more malignant.Gastric cancer lymph nodes micrometastasis is a very important prognostic factor and have close relation with the biological behavior of gastric cancer. So examination in lymph nodes of respective station of gastric cancer has important significances to direct the clinical stage and the extent of lymph nodes resecting of gastric cancer.