Table 1 Distribution of socio-demographic and clinical features, odds ratio (OR) of relapse, and corresponding 95% confidence intervals (CI) in 28 OPSCC patients who recurred within 24 months from end of treatment (cases) and 49 OPSCC patients who did not (controls)

 Male

19

(67.9)

33

(67.4)

1^f

1^f

 Female

9

(32.1)

16

(32.7)

1.07 (0.38–2.97)

1.08 (0.37–3.18)

 <55

10

(35.7)

18

(36.7)

1^f

1^f

 55–59

10

(35.7)

12

(24.5)

1.52 (0.47–4.91)

1.66 (0.49–5.66)

 ≥60

8

(28.6)

19

(38.8)

0.76 (0.25–2.37)

0.90 (0.27–3.00)

 Never

4

(14.3)

10

(20.4)

1^f

1^f

 Former

3

(10.7)

11

(22.5)

0.62 (0.11–3.62)

0.66 (0.11–4.12)

 Current

21

(75.0)

28

(57.1)

1.73 (0.46–6.54)

1.44 (0.32–6.45)

 0–1

5

(17.9)

15

(31.3)

1^f

1^f

 2–3

23

(82.1)

33

(68.7)

2.02 (0.63–6.55)

1.12 (0.42–2.99)

 1–2

11

(39.3)

31

(64.6)

1^f

1^f

 3–4

17

(60.7)

17

(35.4)

3.23 (1.18–8.86)

1.92 (1.02–3.62)

 III

4

(13.8)

12

(25.0)

1^f

1^f

 IV

25

(86.2)

36

(75.0)

2.77 (0.68–11.30)

2.44 (0.58–10.29)

 Negative

23

(82.1)

36

(73.5)

1^f

1^e

 Positive

5

(17.9)

13

(26.5)

0.59 (0.18–1.93)

0.92 (0.24–3.61)

 RT ± CT

16

(57.1)

21

(42.9)

1^f

1^f

 RT + CH ± CT

12

(42.9)

28

(57.1)

0.53 (0.20–1.45)

0.48 (0.16–1.51)

 ≥70%

6

(21.4)

19

(38.8)

1^f

1^f

 50 to <70%

9

(32.1)

17

(34.7)

1.68 (0.48–5.83)

2.18 (0.53–8.97)

 <50%

13

(46.4)

13

(26.5)

3.51 (1.03–12.00)

4.12 (1.01–16.91)

1.45 (1.13–1.87)

1.50 (1.13–2.00)