*4.3.2 The dietary habit of heated foods and risk of colorectal cancer*

Referred to earlier statements regarding cancer occurrence in species, only human's internal organs of lung, liver, stomach, and others are seriously exposed to risk factors and can develop cancer. In contrast, animals suffer from cancer with a very rare occurrence in the internal organs [1, 2]. Animals consume natural foods

**45**

respectively (**Table 10**) [50].

*Colorectal Cancer in Vietnam*

**Parent suffered from cancer**

**Close relative suffered from cancer**

**History of colorectal pain and inflammation**

**Body mass index (BMI) (rectal cancer only)**

*Family and personal history of health and risk of colorectal cancer.*

*P for trend = 0.013*

*P for trend = 0.030*

*Drinking habits and risk of colorectal cancer.*

**Table 8.**

**Table 9.**

*DOI: http://dx.doi.org/10.5772/intechopen.93730*

without any preparation, while humans consume both natural foods and prepared foods [56, 57]. Also, humans used at least 10,000 chemical additives, which serve as contaminants [58]. Besides, heat-generated carcinogens due to the cooking temperature were reported in many previous studies. One of such carcinogens is acrylamide, which was detected in heated foods. It was evaluated by IARC to be a

**Factors Control Case OR 95% CI P**

Yes 8 21 3.00 1.29 6.99 0.011

Yes 5 17 3.63 1.31 10.01 0.013

Yes 15 48 3.68 2.01 6.75 0.000

18.5- < 25 108 119 2.03 .12 3.33 0.005 25- < 30 7 8 2.09 .79 5.51 0.135

**Alcohol and/or beer Control Case OR 95% CI P**

Some drinking per week 29 33 1.61 .90 2.87 0.110 Daily drinking 21 27 1.91 .98 3.72 0.058

Not drinking 175 145 1.00 *Reference*

No 303 290 1.00 *Reference*

No 305 294 1.00 *Reference*

No 286 255 1.00 *Reference*

<18.5 32 17 1.00 *Reference*

The concentration of acrylamide was 50 μg/kg in hamburgers prepared at the temperature of 240°C, while it was zero in the control [60]. With this evidence, we hypothesized that the intake of heated foods might be a contributor to the development of colorectal cancer in our study population. Three food items were categorized to be heated food items because they were heated in cooking temperature at 165°C or higher during preparation processing [56, 57]. The concentration of heat-generated carcinogens (acrylamide) was generated and significantly increased when the temperature increased from 100–240°C [60]. Daily and weekly intake of barbecued meats (Usual outside appearance: medium-, well-, and blackened/charred of cooked meats vs. lightly browned of cooked meats), bread, and biscuits significantly increased the risk of colorectal cancer, with OR = 1.70, 95% CI = 1.09–2.63; OR = 2.15, 95% CI = 1.36–3.40; and OR = 2.05, 95% CI = 1.03–4.07,

potential carcinogen to humans (Group 2A) [59].

### *Colorectal Cancer in Vietnam DOI: http://dx.doi.org/10.5772/intechopen.93730*


### **Table 8.**

*Colorectal Cancer*

**Table 6.**

**Table 7.**

of obesity was unknown.

**4.3 Environmental factors related to colorectal cancer**

95% CI = 0.98–3.72, and *p* for trend <0.05 (**Table 9**) [50].

*4.3.2 The dietary habit of heated foods and risk of colorectal cancer*

ethanol but has a limited water solubility [54].

*4.3.1 Drinking habits of alcohol and/or beer and risk of colorectal cancer*

Alcoholic beverages have been proven to be a major part of human's diet [53]. Excluding the poisonous effect of heavy intake of alcohol, we considered alcoholic beverages as a promoter of cancer in human. Most carcinogenic chemicals have a higher solubility in alcohol than in water. For example, aflatoxin B is soluble in

There is sufficient evidence for the carcinogenicity of alcohol beverages in human but inadequate evidence for the carcinogenicity of ethanol and alcoholic beverages in experimental animals [55]. Based on these facts and figures, we hypothesized that alcoholic beverages are promoters for cancer in humans. In this study, three levels of alcoholic drinking were categorized, including not drinking, some drinking per week, and daily drinking. Those who daily consume alcoholic beverages were at a significantly higher risk of colorectal cancer, with OR = 1.91,

Referred to earlier statements regarding cancer occurrence in species, only human's internal organs of lung, liver, stomach, and others are seriously exposed to risk factors and can develop cancer. In contrast, animals suffer from cancer with a very rare occurrence in the internal organs [1, 2]. Animals consume natural foods

95% CI = 1.31–10.01, respectively. Patients with a past history of colorectal pain and inflammation are also at a higher risk of cancer, with OR = 3.68, 95% CI = 2.01–6.75. Regarding body mass index (BMI), three levels were categorized, including <18.5; 18.5- < 25, and 25- < 30. Patients with body mass index of 25- < 30 are also at a higher risk of cancer, with OR = 2.09, 95% CI = 0.79–5.51, and *p* for trend <0.05 (**Table 8**) [50]. The Vietnamese households traditionally follow the multigenerational pattern and, therefore, members share living environments as well as similar dietary habits. As a result, all family members might be exposed to the risk of cancer, in general, and the risk of colorectal cancer, in particular. Regarding the body mass index, the mechanism of developing colorectal cancer among the group

**Blood type Control Case OR 95% CI P**

A and AB 58 73 1.58 1.05 2.38 0.027

**CYP1A1 genotypes Control Case OR 95% CI P**

AG and GG 226 237 1.86 1.16 2.98 0.010

AA 57 32 1.00 *Reference*

O and B 187 150 1.00 *Reference*

*Blood ABO group and risk of colorectal cancer.*

*CYP1A1 genotypes and the risk of colorectal cancer.*

**44**

*Family and personal history of health and risk of colorectal cancer.*


### **Table 9.**

*Drinking habits and risk of colorectal cancer.*

without any preparation, while humans consume both natural foods and prepared foods [56, 57]. Also, humans used at least 10,000 chemical additives, which serve as contaminants [58]. Besides, heat-generated carcinogens due to the cooking temperature were reported in many previous studies. One of such carcinogens is acrylamide, which was detected in heated foods. It was evaluated by IARC to be a potential carcinogen to humans (Group 2A) [59].

The concentration of acrylamide was 50 μg/kg in hamburgers prepared at the temperature of 240°C, while it was zero in the control [60]. With this evidence, we hypothesized that the intake of heated foods might be a contributor to the development of colorectal cancer in our study population. Three food items were categorized to be heated food items because they were heated in cooking temperature at 165°C or higher during preparation processing [56, 57]. The concentration of heat-generated carcinogens (acrylamide) was generated and significantly increased when the temperature increased from 100–240°C [60]. Daily and weekly intake of barbecued meats (Usual outside appearance: medium-, well-, and blackened/charred of cooked meats vs. lightly browned of cooked meats), bread, and biscuits significantly increased the risk of colorectal cancer, with OR = 1.70, 95% CI = 1.09–2.63; OR = 2.15, 95% CI = 1.36–3.40; and OR = 2.05, 95% CI = 1.03–4.07, respectively (**Table 10**) [50].


### **Table 10.**

*Dietary habits and risk of colorectal cancer.*

### *4.3.3 Cigarette smoking and risk of colorectal cancer*

The heating and burning of tobacco products lead to the formation of mainstream smoke and sidestream smoke. Mainstream smoke from cigarettes and cigars is generated during puff-drawing in the burning cone and hot zones; it travels through the tobacco column and exits from the mouthpiece. Sidestream smoke is formed during puff-drawing and is emitted freely from the smoldering tobacco product into the ambient air. A variety of chemical and physical processes occur in the oxygen-deficient, hydrogen-rich environment of the burning cone at temperatures up to 950°C. Tobacco smoke contains more than 3800 constituents and many of them are chemical carcinogens to humans [61]. Tobacco smoking was reported to be responsible for about 25–35% of all cancer in humans [3]. In our study, daily smoking of 11 cigarettes or more increased the risk of colorectal cancer, with OR = 2.08, 95% CI = 0.62–6.91, but it is not significant (**Table 11**) [50].

Both the burning of tobacco and heating of foods leads to the formation of chemical carcinogens, known as "heat-generated carcinogens" or "dietary carcinogens." Thousands of chemicals were reported in the smoke of burning tobacco and heating foods. These chemicals were detected in the user's blood and urine after the intake of these products [60–67]. With this evidence, we should seriously consider the study of heat-generated carcinogens and dietary carcinogens to prevent the development of cancer in humans.
