الفهرس 
The Anatomy of Lymphatic SystemOnly 14 pages are availabe for public view
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Abstract
The lymphatic system transports lymph from interstitial space in different organs toward the base of the neck. Its pathway begins after resorption from initial lymphatics and lymph transport to progressively larger vessels (lymphatic collectors and trunks), finally reaching the confluence of the internal jugular and subclavian veins as lymphatic and thoracic ducts, respectively, at the right and left venous angles. Even though important physiopathological and therapeutical issues may exist due to the close anatomical, embryological, and functional relationship of blood and lymphatic vessels.
The locoregional lymph nodes is the first site of immune response and spread of cancer, and its anatomical distribution has a great value in the staging of tumors and in performing a complete surgical dissection.
Understanding the mechanism of cancer metastasis is very important and therapies made against cancer are largely dependent on these machanisms, alterations in the cell adhesion molecular function associated with malignant tissues has a great impact on the developing of the metastatic cascade, genetic back ground is also present, the increased expression of matrix metalloprotieneases is associated with many cancer forms and the usage of its inhibitors proved to reduce the growth of cancer in animal models.
The nodal metastasis is a greater indicator of survival and many classifications was admitted for correct evaluation of nodal stage, The classification based on anatomical distribution of metastatic lymph nodes and its distance from the primary tumor gives a good idea and serves for stage identification and predicting survival but was exceeded by the numerical scoring which proved to be easily applicable and more accurate than the previous one regarding errors may be done when determining the site of the dissecting nodes after en bloc resection and the difficulty in assigning the lymph nodes in the correct tier.
The N3 category of stomach cancer which was introduced by the new classification has poorer prognosis than M1, it refers to group of patient with poorer prognosis than those with the paraaortic lymph node metastasis which is considered distant metastasis, however studies used super extended lymphadenectomy revealed improved the 5 year survival in this group of patients.
The ratio based classification then emerges as a modification of the numerical classification and replacing it, data collected from several studies shows the importance of the ratio of positive lymph nodes to a certain suggested values of nodes excised for each anatomical sites involved and for each tumor type.
The rational classification divides patients in to groups using cut off values which differs according to each tumor type and place of surgical dissection, it introduced the concept of complete lymph node dissection as an ideal procedure for nodal dissection under standardized surgical techniques.
The rational classification seams the ideal staging method to depend on, it gathers many variables in one and over comes many technical problems related to the excision of certain number of lymph nodes that was required in the previous model, and categorize patients in to different prognostic groups different from that mentioned in the AJCC classification.
Many studies showed the superiority of the current scheme in overcoming the problem of stage migration that was evident in the previous models, moreover the LN ratio staging system is easy applicable and reproducible and proved to be independent and unique prognostic factor.