|
Variable
|
Irradiation of level Ib, N (%)
|
P
*
|
|---|
|
(−), n = 722
|
(+), n = 182
|
|---|
|
Sex
| | | |
|
Male
|
536 (74.2)
|
122 (67.0)
|
.051
|
|
Female
|
186 (25.8)
|
60 (33.0)
|
|
Age
| | | |
|
<50 years
|
447 (66.1)
|
139 (76.4)
|
.008
|
| ≧50 years |
245 (33.9)
|
43 (23.6)
|
|
T classification
| | | |
|
T1
|
157 (21.7)
|
36 (19.8)
|
.208
|
|
T2
|
108 (15.0)
|
38 (20.9)
|
|
T3
|
332 (46.0)
|
83 (45.6)
|
|
T4
|
125 (17.3)
|
25 (13.7)
|
|
N classification
| | | |
|
N0
|
206 (28.5)
|
21 (11.5)
|
<.001
|
|
N1
|
493 (68.7)
|
137 (75.3)
|
|
N3
|
20 (2.8)
|
24 (13.2)
|
|
Positive RLNs
| |
|
(−)
|
256 (35.5)
|
45 (24.7)
|
.006
|
|
(+)
|
466 (64.5)
|
137 (75.3)
|
|
Positive CLNs
| |
|
(−)
|
479 (66.3)
|
60 (33.0)
|
<.001
|
|
(+)
|
243 (33.7)
|
122 (67.0)
|
|
Positive CLNs at supraclavicular fossa
| |
|
(−)
|
710 (98.3)
|
168 (92.3)
|
<.001
|
|
(+)
|
12 (1.7)
|
14 (7.7)
| |
|
Chemotherapy
| |
|
(−)
|
147 (20.4)
|
15 (8.2)
|
<.001
|
|
(+)
|
575 (79.6)
|
167 (20.1)
|
- Abbreviations: IMRT, intensity-modulated radiotherapy; RLNs, retropharyngeal lymph nodes; CLNs, cervical lymph nodes; ES, extra-capsular spread
- * P-values were calculated using unadjusted chi-square test (or Fisher’s exact test, if indicated)
