The therapeutic ratio may be maintained or improved if selective neck irradiation can be safely implemented in patients with limited nodal disease burden. However, treatment of a large field to the neck is associated with substantial morbidities, both early and late: Early toxicities include brisk radiation dermatitis and odynophagia, especially if concurrent chemo-radiation is utilized late toxicities may include neck fibrosis, lymphedema, brachial plexopathy, and thyroid dysfunction. Results from this and other similar studies have led to the practice of empirical irradiation of the entire neck in treating NPC, regardless of the stage of NPC at diagnosis. However, none of the seven regionally treated patients relapsed.

In a retrospective study reported by Lee et al, 57 (30%) of the 189 patients who did not receive elective neck irradiation subsequently developed cervical lymph node recurrence. The fields of radiation therapy for NPC traditionally encompass the primary disease and involved neck nodes, as well as the entire draining lymphatic regions to the lower neck. Radiation has been the mainstay of definitive treatment for NPC. However, NPC has the highest preponderance for regional lymph node metastasis among head and neck SCC. Like most other squamous cell carcinomas (SCC) of the head and neck primaries, lymphatic drainage of the nasopharynx is predominantly to the cervical lymph nodes. Nasopharyngeal carcinoma (NPC) is the most commonly diagnosed head and neck cancer in Southeast Asia, with a reported annual incidence of 30-80 per 10 5 population in endemic regions. The rarity of metastasis in certain nodal groups and 'skip' metastasis suggest that reduced treatment volume is feasible in conformal radiotherapy for NPC. Lymph node metastasis in NPC follows a predictable and orderly pattern.

Nodal metastases followed an orderly pattern and the probability of 'skip' metastasis between levels varied between 0.5-7.9%. Low-risk node groups included the supraclavicular, levels IA/IB and VI nodes, and parotid nodes with involvement rates at 3%, 0%, 3%, 0%, and 1%, respectively. The overall probability of levels III, IV, and V nodal involvement are 45%, 11%, and 27%, respectively. The most commonly involved regions include retropharyngeal (69%) and level II lymph nodes (70%).

ResultsĨ5% of NPC cases presented with lymphadenopathy. The occurrence of nodal metastasis was calculated and analyzed according to the respective regional nodal levels. MethodsĪ literature search yielded an initial 411 original articles, and 13 studies with 2920 NPC cases staged via MRI were included in this analysis. We studied the pattern and probability of nodal metastasis through a meta-analysis of published evidences, with an aim to establish an evidence-based guideline for selecting and delineation of clinical target volume of neck lymphatics for conformation radiation for NPC. As such, radiotherapy to the entire lymphatic of the neck bilaterally has been empirically practiced even in early stage disease, although not supported by clinical evidence. The characteristics of cervical lymphatic metastasis in nasopharyngeal carcinoma (NPC) are not completely understood.

7 levels of lymph nodes in neck