Table 3. Impact of drinking status according to ALDH2 genotype on disease-free survival in patients with head and neck squamous cell carcinoma.

ALDH2 genotype (rs671)	Drinking status																					P for heterogeneity
	n	n (relapse)	Non			n	n (relapse)	Light			N	N (relapse)	Moderate			N	N (relapse)	Heavy			Ptrend
			HR	95% CI	P-value			HR	95% CI	P-value			HR	95% CI	P-value			HR	95% CI	P-value
Glu/Glu	20	5	1.13	0.42–3.01	0.814	48	13	1.05	0.48–2.31	0.895	22	11	1.77	0.73–4.29	0.204	21	10	2.34	0.93–5.86	0.070	0.029	0.138
Glu/Lys	33	9	1.00	reference	—	54	17	1.27	0.57–2.86	0.557	24	9	1.18	0.47–2.96	0.718	31	6	0.86	0.35–2.14	0.748	0.164
Lys/Lys	12	2	0.49	0.10–2.27	0.359	2	1	2.00	0.22–18.04	0.535	0	0	—			0	0	—			—

ALDH2, aldehyde dehydrogenase 2; HR, hazard ratio; CI, confidence interval.

Drinking status was classified as follows: non, light (<46 g ethanol or <5 days/week), moderate (46–68 g ethanol for ≥5 days/week), and heavy (≥69 g ethanol for ≥5 days/week).

Adjusted for age, sex, performance status, clinical disease stage, primary tumor site, smoking, and definitive treatment.