Table 1 Patient and tumor characteristics

Age < 60 years

36

38.3

13

72.2

5

27.8

Age ≥ 60 years

58

61.7

5

27.8

13

72.2

Age at onset of recurrence disease (years)

62.0 (53–71)

48.0 (45–68)

66.5 (57–73)

(0.006)

Time to first recurrence < 3 months

10

10.3

9

50.0

0

0

Time to first recurrence ≥ 3 months

81

83.5

6

33.3

18

100

Previous recurrence free survival (months)

24.0 (10–73)

2.3 (2–8)

38.1 (18–99)

(0.003)

First recurrence

49

52.1

9

50.0

7

38.9

Several recurrences

45

47.9

9

50.0

11

61.1

Previous treatment

Operation

72

76.6

12

66.7

13

72.2

(0.177)

Chemotherapy

25

26.1

6

33.1

8

44.0

(0.978)

Radiotherapy

63

67.0

15

83.3

17

94.4

(0.584)

Previous total radiation dose (Gy)

64.2 (33–105)

68.1 (50–105)

66.2 (59–77)

(0.696)

rTNM-stage

T1-T2

38

40.4

5

27.8

7

38.9

(0.812)

T3-T4

45

47.9

10

55.6

9

50.0

Tx

9

9.6

3

16.7

2

11.1

N0

67

71.3

13

72.2

12

66.7

(1.000)

N1-N2

21

22.4

3

16.7

4

22.2

N3

3

3.2

2

11.1

1

5.6

UICC-stage

Stage I-II

31

33.0

6

33.3

5

27.8

(1.000)

Stage III-IV

63

67.0

12

66.7

13

72.2

Histology

SCC

75

79.8

17

94.4

15

83.3

(0.735)

Other

19

20.2

1

5.6

3

16.7

Grading

Low Grade (G1-G2)

50

53.2

12

66.7

7

38.9

(0.156)

High Grade (G3-G4)

41

43.6

6

33.3

11

61.1

Localization

Oral cavity

24

25.5

7

38.9

4

22.2

(0.308)

Oro-, nasopharynx

26

27.7

5

27.8

9

50.0

Hypopharynx, larynx

6

6.4

2

11.1

1

5.6

Lymph node

8

8.5

3

16.7

2

11.1

Other

30

31.9

1

5.6

2

11.1

Resection margins

R0

37

39.4

4

22.2

6

33.3

(0.766)

R1

32

34.0

10

55.6

5

27.8

R2

11

11.7

3

16.7

4

22.2

Rx (unsure)

6

6.4

1

5.6

-

-

No debulking

8

8.5

1

5.6

3

16.7

Tissue invasion

L0, V0, Pn0

26

27.7

3

16.7

2

11.1

(0.733)

L1, V1 or Pn1

20

21.3

5

27.8

7

38.9

No neck dissection

48

51.1

10

55.6

9

50,0

(1.000)