Genetic variants of p27 and p21 as predictors for risk of second primary malignancy in patients with index squamous cell carcinoma of head and neck

Table 3 SPM risk associated with p27/p21 polymorphisms after index SCCHN

No. variant genotypes	Total (No. = 1,292)		SPM-free (No. = 1,172)		SPM (No. = 120)		P ^a	HR (95% CI)^b
	No.	%	No.	%	No.	%
0 (Ref.^c)	606	46.9	572	48.8	34	28.3	< 0.001	1.0 (Ref.)
1	499	38.6	442	37.7	57	47.5		2.2 (1.4-3.4)
2	107	8.3	92	7.9	15	12.5		2.8 (1.5-5.3)
3	80	6.2	66	5.6	14	11.7		3.0 (1.6-5.7)
Trend								P = 0.0002
No variants (Ref.^c)	606	46.9	572	48.8	34	28.3	< 0.001	1.0 (Ref.)
With variants	686	53.1	600	51.2	86	71.7		2.4 (1.6-3.6)

^aχ² test for differences in the distribution of combined variant genotypes between the patients who developed SPM and the patients who did not
^bAdjusted for age, sex, ethnicity, tobacco smoking and alcohol drinking in a Cox model
^cRef. = reference group

ISSN: 1476-4598