Obesity as a risk factor for early-onset colorectal cancer: Evidence from a nationally representative database

Table 1 Baseline characteristics of study participants

	Overall	Non eoCRC	eoCRC	P value
Number (n)	30321	30273	48
Age (year)	34.37 ± 8.61	34.36 ± 8.61	39.96 ± 7.61	< 0.001
Gender	16170 (53.3)	16146 (53.3)	24 (50.0)	0.751
Smoker	11945 (39.4)	11912 (39.3)	33 (68.8)	< 0.001
Heavy drinker	4493 (18.8)	4493 (18.8)	0 (0.0)	0.006
BRI quartile				0.002
Q1 (lowest)	10176 (34.7)	10171 (34.7)	5 (11.1)
Q2	7364 (25.1)	7350 (25.1)	14 (31.1)
Q3	5972 (20.4)	5963 (20.4)	9 (20.0)
Q4 (highest)	5827 (19.9)	5810 (19.8)	17 (37.8)
Waist circumference (cm)	96.44 ± 16.86	96.43 ± 16.86	105.73 ± 13.97	< 0.001
	14369 (49.0)	14337 (48.9)	32 (71.1)	0.005
BMI				0.028
Normal weight	9893 (32.6)	9886 (32.7)	7 (14.6)
Overweight	9519 (31.4)	9500 (31.4)	19 (39.6)
Obese	10909 (36.0)	10887 (36.0)	22 (45.8)
Height (cm)	168.21 ± 9.99	168.21 ± 9.99	169.22 ± 9.36	0.484
Weight (kg)	82.05 ± 22.61	82.04 ± 22.62	88.12 ± 18.09	0.063
BRI	5.06 ± 2.35	5.05 ± 2.35	6.19 ± 2.23	0.001
BMI	28.92 ± 7.30	28.92 ± 7.30	30.84 ± 6.43	0.068

Categorical variables were treated as factors and summarized as frequencies and percentages, while continuous variables were presented as mean ± SD or median (IQR), as appropriate. A comparison between groups were performed using Student’s t-test or Wilcoxon rank-sum test for continuous variables and χ² or Fisher’s exact test for categorical variables. P < 0.05 were considered as significant value. eoCRC: Early-onset colorectal cancer; BRI: Body roundness index; BMI: Body mass index.

Table 2 Summary of unadjusted Logistic regression results

	OR	Std. Error	P value	95%CI (lower)	95%CI (upper)
BRI quartile 2	14.23	4.49	< 0.011	2.64	1.42
BRI quartile 3	17.73	5.03	< 0.012	3.23	1.42
BRI quartile 4	31.84	10.12	< 0.001	3.22	5.92
Obesity (BMI)	12.55	4.77	< 0.002	2.36	1.81
Overweight (BMI)	10.99	4.03	< 0.006	2.06	1.48
Obese (waist)	7.86	3.62	0.001	1.43	1.67

We compared body roundness index quartiles to waist and body mass index. P < 0.05 were considered as significant value. OR: Odds ratio; 95%CI: 95% confidence interval; BRI: Body roundness index; BMI: Body mass index.

Table 3 Summary of adjusted Logistic regression results

Variable	OR	Std. Error	P value	95%CI (lower)	95%CI (upper)
BRI quartile 2	4.1	2.29	< 0.012	1.37	12.26
BRI quartile 3	4.36	2.64	< 0.015	1.33	14.31
BRI quartile 4	9.74	5.52	< 0.0001	3.2	29.6
Obesity (BMI)	4.26	2.02	< 0.002	1.68	10.8
Overweight (BMI)	3.75	1.81	< 0.006	1.46	9.67
Obese (waist)	1.14	0.37	0.002	0.41	1.86
Smoker	2.43	0.85	< 0.011	1.22	4.83
Not heavy drinker	0.67	0.28	0.341	0.29	1.53

We compared body roundness index quartiles to waist and body mass index while adjusting for smoking and heavy drinking. P < 0.05 were considered as significant value. OR: Odds ratio; 95%CI: 95% confidence interval; BRI: Body roundness index; BMI: Body mass index.

Table 4 Independent contributions of body roundness index, body mass index, and waist circumference to early-onset colorectal cancer risk

Variable	BRI + BMI model		BRI + waist model		BRI + BMI + waist model
	OR	P value	OR	P value	OR	P value
BRI quartile 2	4.61	0.106	4.02	0.024	3.95	0.158
BRI quartile 3	6.47	0.097	3.92	0.082	4.76	0.199
BRI quartile 4	16.04	0.018	7.7	0.007	11.7	0.053
Obese (BMI)	0.62	0.64			0.6	0.615
Overweight (BMI)	1.05	0.96			1.07	0.936
Obese (waist)			1.34	0.608	1.46	0.506

We assessed the significant of body roundness index across 3 different models (model 1 body roundness index + body mass index; model 2 body roundness index + waist; and model 3 body roundness index + body mass index + waist). P < 0.05 were considered as significant value. BRI: Body roundness index; BMI: Body mass index.