Lymph Node Classification
The presence in our body of a rich network of lymph vessels and numerous lymph node stations prompted several authors to draw up classifications that would take into account lymph drainage pathways in the various districts and would be useful for describi
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Lymph Node Classification
The presence in our body of a rich network of lymph vessels and numerous lymph node stations prompted several authors to draw up classifications that would take into account lymph drainage pathways in the various districts and would be useful for describing tumor progression pathways. The lymph node classifications of different anatomical regions, mostly prepared by surgeons, have provided valuable help for the execution and standardization of surgical procedures, offering an effective tool for ensuring their reproducibility. With the development of new radiotherapy techniques, especially conformal radiotherapy, radiation oncologists have also started using these classifications to define the nodal clinical target volume (CTV) [7, 8] that appears to be increasingly selective. We have considered the following classifications for lymph node contouring on CT: •• Head and neck region, classification of the American Head and Neck Society/American Academy of Otolaryngology Head and Neck Surgery (AHNS/AAO-HNS, 1998, Robbins classification). •• Mediastinal region, American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) classification, 1996 (Mountain and Dresler). •• Upper abdominal region, classification of the Japanese Gastric Cancer Association (JGCA).
•• Pelvic region, we referred to the distribution of lymph node groups relative to the main arteries.
2.1 Head and Neck Region For nearly four decades, the most commonly used classification of cervical lymph nodes was that developed by Rouvière [2] in 1938, based on a previous classification by Trotter (1930) [9] which was based on an earlier study by Poirer and Charpy in 1909 [10]. This classification defined lymph node areas based on anatomical limits established through palpation or surgical dissection. In subsequent years, the need was felt for a classification based on new clinical and pathophysiological considerations, specifically, in relation to surgical neck dissection techniques; consequently, several new classification systems were proposed [11–14]. In 1991 the AAO-HNS classified neck lymph nodes into levels, following a system originally proposed by the Memorial Sloan-Kettering Cancer Group (New York) [15]. This classification, also known as the Robbins classification [16], distinguishes six levels: •• IA, submental lymph nodes •• IB, submandibular lymph nodes •• II, upper jugular lymph nodes •• III, middle jugular lymph nodes •• IV, lower jugular lymph nodes
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A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy
•• V, posterior triangle lymph nodes •• VI, anterior compartment lymph nodes It considers the lymph nodes that are removed during neck dissections. The lymph nodes that are not commonly removed, such as retropharyngeal, parotid, buccal, and occipital nodes, are not included in the Robbins classification. Subsequently, this classification was recommended by the UICC [17]. In 1992, in the TNM classification of malignant tumors, the division of the head and neck ly
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