Table 1 Patient characteristics

Age (years)

 Median

48

52

0.398

 Range

29–78

24–78

Gender

 Male

78 (98.7 %)

70 (95.9 %)

0.274

 Female

1 (1.3 %)

3 (4.1 %)

Subsite

 Oral tongue

25 (31.6 %)

35 (47.9 %)

0.348

 Buccal mucosa

34 (43.0 %)

25 (34.2 %)

 Alveolar ridge

8 (10.1 %)

7 (9.6 %)

 Retromolar trigone

5 (6.3 %)

3 (4.1 %)

 Floor of the mouth

2 (2.5 %)

2 (2.7 %)

 Hard palate

2 (2.5 %)

1 (1.4 %)

 Lip

3 (3.8 %)

0

Resection-margin status

 Close or positive

39 (49.4 %)

42 (57.5 %)

0.313

 Negative

40 (50.6 %)

31 (42.5 %)

Extracapsular spread

 Positive

13 (16.5 %)

19 (26.0 %)

0.148

 Negative

66 (83.5 %)

54 (74.0 %)

Perineural involvement

 Positive

49 (62.0 %)

60 (82.2 %)

0.006

 Negative

30 (38.0 %)

13 (17.8 %)

Lymphovascular space involvement

 Positive

31 (39.2 %)

46 (63.0 %)

0.003

 Negative

48 (60.8 %)

27 (37.0 %)

Pathology stage:

Tumor stage

 Stage I

6 (7.6 %)

8 (11.0 %)

0.532

 Stage II

12 (15.2 %)

12 (16.4 %)

 Stage III

18 (22.8 %)

15 (20.5 %)

 Stage IVA

43 (54.4 %)

38 (52.1 %)

Primary tumor stage

 T1

14 (17.7 %)

13 (17.8 %)

0.768

 T2

22 (27.8 %)

25 (34.2 %)

 T3

18 (22.8 %)

11 (15.1 %)

 T4a

25 (31.6 %)

24 (32.9 %)

Regional lymph node stage

 N0

39 (49.4 %)

38 (52.1 %)

0.302

 N1

15 (19.0 %)

7 (9.6 %)

 N2a

8 (10.1 %)

6 (8.2 %)

 N2b

14 (17.7 %)

20 (27.4 %)

 N2c

3 (3.8 %)

1 (1.4 %)

 N3

0

1 (1.4 %)

Adjuvant concurrent chemotherapy

 Yes

67 (84.8 %)

65 (89.0 %)

0.442

 No

12 (15.2 %)

8 (11.0 %)

RT dose

 Median (range)

66 Gy (59.4–72 Gy)

66 Gy (60–70.2 Gy)

0.304

POTT

 ≤13 weeks

46 (58.2 %)

61 (83.6 %)

0.001

 >13 weeks

33 (41.8 %)

12 (16.4 %)

OTTRT

 ≤8 weeks

54 (68.4 %)

65 (89.0 %)

0.002

 >8 weeks

25 (31.6 %)

8 (11.0 %)