[Regulation for distribution of metastatic cervical lymph nodes of 512 cases of nasopharyngeal carcinoma]

Abstract

Background & objective: To identify the target volume of radiotherapy is more and more important. This study was designed to explore the regulation for the distribution of metastatic cervical lymph nodes of nasopharyngeal carcinoma (NPC) and to recommend the delineation of clinical target volume of the neck for three-dimensional conformal radiotherapy in NPC.

Methods: From Jan. 2003 to Jun. 2004, 512 of cases of NPC, histologically diagnosed, received enhanced transversal CT scan. The cervical node was divided into six levels (I-VI) plus retropharyngeal nodes according to RTOG guidelines proposed in 2003.

Results: Of 512 patients, 328 (64.1%) had cervical lymphadenopathy at presentation. Of the 328 neck positive cases, the node involvement was unilateral in 61.3% patient and bilateral in 38.7%. 328 (64.1%) cases showed enlargement of retropharyngeal node, and unilateral 50.9%, bilateral 49.1%. The involvement for levelIto level VI and retropharyngeal area in node-positive cases was 3.0%, 97.9%, 46.0%, 9.5%, 13.7%, 0% and 74.4%. Of the node-positive patient, the incidence of skip metastasis was from 4.6% to 6.5%. 25.3% of the node-positive cases showed involvement, which is beyond CTV for the neck of stage N0 recommended by RTOG.

Conclusions: The cervical node involvement of NPC is spread orderly down the neck, and the incidence of skip metastasis is lower. Retropharyneal node was the first echo node to metastases of NPC. The retropharyngeal node, level II, and level III were the most frequently involved area. Level Ia and level VI were never involved. There are few cases with positive nodes beyond CTV for the neck of stage N0 recommended by RTOG. Our data is helpful for the delineation cervical target in the 3-D conformal radiotherapy of NPC.