Table 4.

Stratified analysis for association between apoptosis capacity (AC, %) and risk of squamous cell carcinoma of the head and neck (SCCHN) in a North American population

Variable	Cases (n = 703)a	Controls (n = 685)a	Crude OR (95% CI)	Adjusted OR (95% CI)b	Pc	P interationd
All subjects:	402/301	343/342	1.33 (1.08–1.65)	1.42 (1.13–1.78)	0.002
Age
<57 (years)	186/166	171/166	1.08 (0.80–1.46)	1.17 (0.85–1.61)	0.323
≥57 (years)	216/135	172/176	1.62 (1.20–2.19)	1.73 (1.25–2.38)	0.0009	0.015
Sex
Female	95/75	110/58	0.65 (0.42–1.00)	0.66 (0.40–1.06)	0.087
Male	307/226	233/284	1.65 (1.29–2.11)	1.76 (1.36–2.27)	<0.0001	0.005
Race
Caucasians	369/278	324/323	1.32 (1.06–1.65)	1.41 (1.12–1.78)	0.004
Others	33/23	19/19	1.24 (0.53–2.90)	1.98 (0.72–5.47)	0.187	0.697
Smoking status
Never	153/97	195/168	1.36 (0.98–1.89)	1.36 (0.97–1.90)	0.074
Ever	248/204	148/172	1.41 (1.06–1.88)	1.48 (1.10–1.99)	0.009	0.566
Alcohol status
Never	109/78	168/126	1.05 (0.72–1.52)	1.02 (0.70–1.51)	0.905
Ever	292/223	175/212	1.60 (1.23–2.09)	1.67 (1.27–2.21)	0.0003	0.009
Tumor site
Oropharynx	215/152	343/342	1.40 (1.09–1.81)	1.59 (1.21–2.07)	0.0008
Non-oropharynx	186/149	343/342	1.23 (0.95–1.60)	1.26 (0.94–1.68)	0.121
T stage
T1	120/81	343/342	1.47 (1.07–2.02)	1.55 (1.12–2.16)	0.009
T2	148/112	343/342	1.31 (0.98–1.75)	1.46 (1.08–1.97)	0.014
T3	71/52	343/342	1.33 (0.90–1.97)	1.39 (0.91–2.10)	0.126
T4	62/56	343/342	1.10 (0.74–1.62)	1.37 (0.89–2.12)	0.158
T1/T2	268/193	343/342	1.38 (1.09–1.75)	1.47 (1.15–1.89)	0.002
T3/T4	133/108	343/342	1.21 (0.90–1.63)	1.34 (0.97–1.87)	0.081
N stage
N0	130/102	343/342	1.26 (0.94–1.71)	1.32 (0.96–1.82)	0.092
N1	48/29	343/342	1.61 (0.99–2.61)	1.77 (1.07–2.94)	0.027
N2	217/164	343/342	1.31 (1.02–1.69)	1.50 (1.15–1.97)	0.003
N3	6/6	343/342	0.99 (0.32–3.10)	1.19 (0.36–3.91)	0.774
N0/N1	178/131	343/342	1.34 (1.02–1.76)	1.41 (1.05–1.88)	0.021
N2/N3	223/170	343/342	1.30 (1.01–1.67)	1.49 (1.14–1.94)	0.003
Overall stage
I	60/37	343/342	1.61 (1.04–2.49)	1.60 (1.02–2.50)	0.041
II	35/37	343/342	0.94 (0.58–1.52)	1.01 (0.61–1.69)	0.956
III	65/36	343/342	1.76 (1.14–2.72)	1.89 (1.20–2.99)	0.006
IV	241/191	343/342	1.25 (0.98–1.59)	1.47 (1.13–1.90)	0.004
I/II	95/74	343/342	1.27 (0.91–1.79)	1.28 (0.90–1.83)	0.167
III/IV	306/227	343/342	1.33 (1.06–1.67)	1.51 (1.18–1.93)	0.001

^aLow AC group (<51.3)/high AC group (≥51.3) using the median apoptotic capacity in controls as the cutoff point value.

^bAdjusted for age, sex and smoking status in logistic regression models when appropriate.

^cObtained from the logistic regression model with adjustment for age, sex, race, smoking and alcohol status.

^dInteraction P values for quartile apoptotic capacity using logistic regression model with adjustment for age, sex, race, smoking and alcohol status.