Role of body mass index in colon cancer patients in Taiwan

Table 1 Patient and tumor characteristics stratified according to body mass index category

	Percentage of patients within each BMI category
	Under-weight(n = 164)	Normal weight(n = 1109)	Over-weight(n = 550)	Obese(n = 315)	P value
Age at diagnosis (yr)					< 0.001
≤ 40	12.8	8.7	5.8	4.8
41-75	57.3	75.5	81.6	83.2
> 75	29.9	15.9	12.5	12.1
Gender (%)
Female	65.9	47.2	44.7	48.3	< 0.001
Tumor location
Right	47.0	41.6	35.5	29.5	< 0.001
Tumor grade
High-to-moderate differentiation	82.9	83.7	85.6	87.9	0.239
Tumor stage					< 0.001
I	9.1	9.2	15.3	19.4
II	48.2	50.9	44.7	45.1
III	42.7	39.9	40.0	35.6
Emergent operation	3.7	3.4	2.5	2.2	0.584
Body weight loss	57.9	45.5	33.3	20.8	< 0.001
CEA > 5 ng/mL	44.2	34.6	36.3	36.0	0.150
Albumin < 35 g/L	42.3	21.0	13.5	11.6	< 0.001
Hemoglobin < 10 g/dL	40.9	32.9	23.2	21.3	< 0.001
Comorbidities
None	57.3	51.7	50.1	41.6	< 0.001
Hypertension	11.0	19.7	26.2	34.9	< 0.001
Heart disease	8.5	6.8	7.6	12.7	0.008
Previous stroke	3.0	3.4	4.5	4.8	0.527
Asthma	3.7	3.3	3.6	2.9	0.936
Diabetes mellitus	4.9	10.6	12.4	20.6	< 0.001
Peptic ulcer disease	14.0	10.8	9.1	8.9	0.229
Chronic hepatitis	1.2	4.3	3.3	4.1	0.225
Liver cirrhosis	1.8	1.4	1.1	0.6	0.650
Renal insufficiency	5.2	8.9	6.8	9.4	0.202
Others	16.6	13.8	12.0	15.1	0.555

Except where stated otherwise, data are the percentage of the particular body mass index (BMI) category population. CEA: Carcinoembryonic antigen.

Table 2 Univariate analysis of survival of colon cancer patients stratified according to body mass index category (Taiwan vs World Health Organization)

	Underweight (n = 164)	Normal weight (n = 1109)	Overweight (n = 550)	Obese (n = 315)
BMI category in Taiwan
Overall survival
5-yr survival rate	60.0	73.6	78.2	75.4
HR (95% CI)	1.67 (1.31-2.13)	Reference	0.83 (0.69-0.99)	0.93 (0.74-1.16)
P value	< 0.001		0.046	0.500
Disease-free survival
5-yr survival rate	57.4	70.8	73.4	71.0
HR (95% CI)	1.60 (1.26-2.04)	Reference	0.86 (0.72-1.04)	0.97 (0.79-1.20)
P value	< 0.001		0.103	0.807
Cancer-specific survival
5-yr survival rate	71.6	78.5	78.9	77.3
HR (95% CI)	1.31 (0.94-1.82)	Reference	0.95 (0.77-1.19)	1.01 (0.78-1.32)
P value	0.107		0.657	0.932
BMI categories of WHO	Underweight (n = 164)	Normal-weight (n = 1331)	Overweight (n = 553)	Obese (n = 90)
Overall survival
5-yr survival rate	60.0	74.0	78.2	75.0
HR (95% CI)	1.70 (1.34-2.15)	Reference	0.85 (0.71-1.02)	0.99 (0.66-1.39)
P value	< 0.001		0.072	0.833
Disease-free survival
5-yr survival rate	57.4	71.0	73.2	70.4
HR ( 95% CI)	1.62 (1.28-2.06)	Reference	0.89 (0.74-1.05)	1.05 (0.73-1.49)
P value	< 0.001		0.169	0.808
Cancer-specific survival
5-yr survival rate	71.6	78.2	79.5	75.0
HR (95% CI)	1.30 (0.94-1.80)	Reference	0.92 (0.74-1.13)	1.10 (0.72-1.70)
P value	0.113		0.418	0.661

Except where stated otherwise, data are the percentage of the particular body mass index (BMI) category population. WHO: World Health Organization; HR: Hazard ratio; CI: Confidence interval.

Table 3 Multivariate analysis of colon cancer survival (overall, disease-free, and cancer-specific) by Cox regression model

Variable	Overall survival		Disease-free survival		Cancer-specific survival
	P value	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)
BMI group	0.000		0.002		0.369
Underweight vs normal	0.000	1.58 (1.23-2.05)	0.002	1.49 (1.16-1.93)	0.107	1.33 (0.94-1.87)
Overweight vs normal	0.060	0.83 (0.68-1.01)	0.123	0.86 (0.71-1.04)	0.751	0.96 (0.76-1.22)
Obese vs normal	0.578	0.94 (0.74-1.18)	0.972	1.00 (0.79-1.25)	0.677	1.06 (0.80-1.41)
TNM stage	0.000		0.000		0.000
II vs I	0.721	1.06 (0.77-1.45)	0.981	1.00 (0.74-1.35)	0.025	1.78 (1.07-2.95)
III vs I	0.000	1.90 (1.39-2.60)	0.000	1.80 (1.34-2.42)	0.000	3.94 (2.39-6.48)
Age group (yr)	0.000		0.000		0.876
41-75 vs ≤ 40	0.054	1.45 (0.99-2.11)	0.052	1.44 (0.99-2.09)	0.672	1.09 (0.74-1.58)
> 75 vs ≤ 40	0.000	3.14 (2.11-4.67)	0.000	2.88 (1.94-4.25)	0.607	1.12 (0.72-1.74)
Gender (male vs female)	0.329	1.08 (0.92-1.27)	0.220	1.10 (0.94-1.29)	0.734	1.03 (0.85-1.26)
Medical illness (comorbidity)	0.003		0.003		0.769
One or two kinds vs none	0.358	1.09 (0.91-1.32)	0.442	1.08 (0.89-1.29)	0.927	0.99 (0.79-1.24)
> two kinds vs none	0.001	1.40 (1.16-1.71)	0.001	1.39 (1.15-1.68)	0.478	0.91 (0.70-1.18)
CEA (> 5 vs ≤ 5 ng/mL)	0.000	1.86 (1.58-2.18)	0.000	1.93 (1.65-2.25)	0.000	2.15 (1.77-2.61)
Hemoglobin (< 10 vs≥ 10 g/dL)	0.913	1.01 (0.84-1.22)	0.760	1.03 (0.86-1.23)	0.835	1.03 (0.81-1.29)
Albumin (normal vs hypoalbuminemia)	0.000	0.65 (0.54-0.79)	0.000	0.68 (0.57-0.83)	0.297	0.87 (0.67-1.13)
Operation timing (emergent vs elective)	0.562	1.21 (0.64-2.26)	0.416	1.28 (0.70-2.34)	0.687	1.18 (0.53-2.66)
Morbidity (yes vs no)	0.000	1.55 (1.26-1.91)	0.000	1.50 (1.23-1.84)	0.279	1.17 (0.88-1.56)
Tumor location (left vs right)	0.785	1.03 (0.86-1.22)	0.666	1.04 (0.88-1.23)	0.583	1.06 (0.86-1.32)
Histologic type	0.079		0.144		0.055
Signet ring cell vs adenocarcinoma	0.039	2.19 (1.04-4.63)	0.065	2.03 (0.96-4.30)	0.017	2.68 (1.19-6.01)
Mucinous vs adenocarcinoma	0.323	1.14 (0.88-1.49)	0.465	1.10 (0.85-1.43)	0.690	1.07 (0.77-1.48)
Histologic grade (differentiation)	0.282		0.213		0.173
Moderate vs high	0.363	1.11 (0.89-1.37)	0.143	1.17 (0.95-1.45)	0.061	1.32 (0.99-1.76)
Low vs high	0.114	1.34 (0.93-1.94)	0.121	1.33 (0.93-1.92)	0.403	1.24 (0.75-2.04)

HR: Hazard ratio; CI: Confidence interval; BMI: Body mass index; TNM: Tumor, nodes, metastasis; CEA: Carcinoembryonic antigen.

Table 4 Results of multivariate analysis of colon cancer survival stratified according to body mass index category

	Underweight	Normal weight	Overweight	Obese
All patients (n = 2138)
Overall survival
HR (95% CI)1	1.58 (1.23-2.05)	Reference	0.83 (0.68-1.01)	0.94 (0.74-1.18)
P value2	< 0.001		0.060	0.578
Disease-free survival
HR (95% CI)1	1.49 (1.16-1.93)	Reference	0.86 (0.71-1.04)	1.00 (0.79-1.25)
P value2	0.002		0.123	0.972
Cancer-specific survival
HR (95% CI)1
P value2	1.33 (0.94-1.87)	Reference	0.96 (0.76-1.22)	1.06 (0.80-1.41)
	0.107		0.751	0.677
Males (n = 1109)
Overall survival
HR (95% CI)	1.55 (1.03-2.35)	Reference	0.77 (0.58-1.01)	0.91 (0.66-1.25)
P value2	0.036		0.056	0.565
Disease-free survival
HR (95% CI)1	1.60 (1.04-2.44)	Reference	0.84 (0.65-1.09)	1.01 (0.75-1.37)
P value2	0.031		0.192	0.937
Cancer-specific survival
HR (95% CI)1
P value2	1.46 (0.84-2.52)	Reference	0.96 (0.69-1.32)	1.21 (0.83-1.77)
	0.179		0.789	0.328
Females (n = 1029)
Overall survival
HR (95% CI)1	1.55 (1.11-2.16)	Reference	0.95 (0.71-1.27)	0.99 (0.69-1.41)
P value2	0.011		0.724	0.945
Disease-free survival
HR (95% CI)1	1.41 (1.01-1.97)	Reference	0.91 (0.68-1.22)	1.01 (0.71-1.43)
P value2	0.042		0.544	0.957
Cancer-specific survival
HR (95% CI)1
P value2	1.16 (0.75-1.82)	Reference	0.96 (0.69-1.36)	0.93 (0.60-1.43)
	0.508		0.839	0.727

¹HR was calculated using the Cox regression model; the variables in the multivariate analysis included TNM stage, age, gender (when analyzing all patients), comorbidities, CEA, hemoglobin, albumin, operative timing, postoperative morbidity, tumor location, histologic type, and histologic grade;

²Each category compared to normal-weight patients. HR: Hazard ratio; CI: Confidence interval; BMI: Body mass index; TNM: Tumor, nodes, metastasis; CEA: Carcinoembryonic antigen.