Extension of local disease in nasopharyngeal carcinoma detected by magnetic resonance imaging: improvement of clinical target volume delineation.
OBJECTIVE
To define by MRI the local extension patterns in patients presenting with nasopharyngeal carcinoma (NPC) and to improve clinical target volume delineation.


METHODS
Consecutive patients (N = 943) with newly diagnosed and untreated NPC were included in this study. All patients underwent MRI of the nasopharynx and neck, which was reviewed by two radiologists.


RESULTS
According to the incidence rates of tumor invasion, the anatomic sites surrounding the nasopharynx were initially classified into three risk grades: high risk (> or = 35%), medium risk (> or = 5-35%), and low risk (< 5%). Incidence rates of tumor invasion into anatomic sites at medium risk were increased, reaching 55.2%, when adjacent high-risk anatomic sites were involved. However, the rates were substantially lower, mostly < 10%, when adjacent high-risk sites were not involved. The incidence rates of concurrent tumor invasion into bilateral sites were < 10%, except in the case of prevertebral muscle involvement (13.1%). Among the 178 incidences of cavernous sinus invasion, there were often two or more simultaneous infiltration routes (60.6%); when only one route was involved, the foramen ovale was the most common (26.4%).


CONCLUSIONS
In patients presenting with NPC, local disease spreads stepwise from proximal sites to more distal sites. Tumors extend quickly through privileged pathways such as neural foramina. The anatomic sites surrounding the nasopharynx are at low risk of concurrent bilateral tumor invasion. Selective radiotherapy of the local disease in NPC may be feasible.
Liang
Shao-Bo
SB
State Key Laboratory of Oncology in Southern China, Guangzhou, People's Republic of China.
Sun
Ying
Y
Liu
Li-Zhi
LZ
Chen
Yong
Y
Chen
Lei
L
Mao
Yan-Ping
YP
Tang
Ling-Long
LL
Tian
Li
L
Lin
Ai-Hua
AH
Liu
Meng-Zhong
MZ
Li
Li
L
Ma
Jun
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D002426:Cavernous Sinus / Q000473:pathology; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000473:pathology; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D018570:Risk Assessment; D047368:Tumor Burden; D055815:Young Adult