MRI-detected skull-base invasion: prognostic value and therapeutic implication in intensity-modulated radiotherapy treatment for nasopharyngeal carcinoma.
OBJECTIVE
With advances in imaging and radiotherapy, the prognostic value of skull-base invasion in nasopharyngeal carcinoma (NPC) needs to be reassessed. We aimed to define a classification system and evaluate the prognostic value of the classification of magnetic resonance imaging (MRI)-detected skull-base invasion in NPC treated with intensity-modulated radiotherapy (IMRT).


METHODS
We retrospectively reviewed 749 patients who underwent MRI and were subsequently histologically diagnosed with nondisseminated NPC and treated with IMRT.


RESULTS
MRI-detected skull-base invasion was not found to be an independent prognostic factor for overall survival (OS), distant metastasis-free survival (DMFS), local relapse-free survival (LRFS), or disease-free survival (DFS; p > 0.05 for all). Skull-base invasion was classified according to the incidence of each site (type I sites inside pharyngobasilar fascia and clivus vs. type II sites outside pharyngobasilar fascia). The 5-year OS, DMFS, LRFS, and DFS rates in the classification of skull-base invasion in NPC were 83 vs. 67 %, 85 vs.75 %, 95 vs. 88 %, and 76 vs. 62 %, respectively (p < 0.05 for all). Multivariate analysis indicated the classification of skull-base invasion was an independent prognostic factor.


CONCLUSIONS
MRI-detected skull-base invasion is not an independent prognostic factor in patients with NPC treated with IMRT. However, classification according to the site of invasion has prognostic value. Therefore, patients with various subclassifications of stage T3 disease may receive treatment with different intensities; however, further studies are warranted to prove this.
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, P.R. China.
Yi-Kan
YK
Cheng
Li-Zhi
LZ
Liu
Ning
N
Jiang
Dan
D
Yue
Ling-Long
LL
Tang
Fan
F
Zhang
Li
L
Lin
Xu
X
Liu
Lei
L
Chen
Jun
J
Ma
D000293:Adolescent; D000328:Adult; D000368:Aged; D002681:China / Q000453:epidemiology; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D009361:Neoplasm Invasiveness; D015995:Prevalence; D011379:Prognosis; D020266:Radiotherapy, Conformal / Q000401:mortality*; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D019292:Skull Base Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult