Association between cigarette smoking, APCmutations and the risk of developing sporadic colorectal adenomas and carcinomas

Table 1 Distribution of selected characteristics by case-control status.

		Cases
Characteristics	Controls n = 334	Adenoma cases n = 45	CRC cases n = 88
Men^a	129 (39%)	29 (65%)	53 (60%)
Women^a	205 (61%)	16 (35%)	35 (40%)
Mean age at cohort entry^b	54.3 ± 3.4	57.5 ± 3.6	68.1 ± 9.7
Mean body mass index. kg/m^b	26.05 ± 3.7	27.2 ± 5.7	25.0 ± 3.8
Smoking parameters*
Ever smoked^c	53% (177/334)	73% (32/44)	67% (56/83)
Mean no. of cigarettes per day^c	10.64 ± 7.3	13.1 ± 6.5	12.7 ± 8.7
Mean no. of years of smoking^c	22.0 ± 11.3	33.6 ± 10.3	33.3 ± 15.0
Mean years since starting smoking^d	34.3 ± 6.8	39.2 ± 6.2	47.0 ± 8.7

*Missing values for smoking parameters gave rise to diminished numbers of cases.
^aThere are significant differences in no. of males and females among the control group and the adenoma and CRC case groups, P = 0.001 and < 10^-4 respectively, but no difference between the two case groups P = 0.64.
^bThere are significant differences in age between the control group and both of the case groups, and between the adenoma and CRC case groups, P < 10^-4.
^cThere are significantly more ever smokers in the adenoma and CRC case groups compared to the controls, P = 0.013 and 0.017, respectively, but no significant difference between the case groups P = 0.54. There is no significant difference between the control group and the adenoma and CRC case groups in number of cigarettes smoked per day, P = 0.07 and 0.15, respectively. There are significant differences between the control group and both of the case groups for duration of smoking P < 10^-4.
^dThere are significant differences in years since starting smoking between the control group and both of the case groups, and also between the adenoma and CRC case groups, P < 10^-4.

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