Assessment of Lifetime Risk of Colorectal Cancer from Smoking among Ethnic Populations in Missouri: A population-based study
Henry O Agbonpolo*
Department of Public Health and Sports Medicine, Missouri State University, Missouri, USA
*Corresponding author: Henry O Agbonpolo, Department of Public Health and Sports Medicine, Missouri State University, 901S National Ave, Springfield, 65897, Missouri, USA.
Citation: Agbonpolo HO (2022) Assessment of Lifetime Risk of Colorectal Cancer from Smoking among Ethnic Populations in Missouri: A population-based study. J Glob Epidemiol Environ Health 2022: 12-15.
Received: 19 October, 2022; Accepted: 09 December, 2022; Published: 16 December, 2022
Objectives: To determine the disease burden of colorectal cancer from smoking among ethnic groups in Missouri. Methods: We used data from population-based studies done in Missouri and evaluated data from studies using an Excel spreadsheet® to determine the disease burden of colorectal cancer risk from smoking among Missourians. Results: Out of the total black Missourians (629,391), 140,512 were smokers. In contrast, out of the entire Missouri population (6,059,651), nonblacks accounted for 5,430,260 and 856,281 of them were smokers, making the entire number of smokers in Missouri 996,793. Eight thousand nine and ninety (8,990) non-black smokers were predicted to have developed colorectal cancer from smoking. In contrast, the number of black smokers who was predicted to have developed colorectal cancer from smoking was 3,245 persons, making the total estimated cases of colorectal cancer 12,235. Conclusion: Smoking provides a significant disease burden to Missouri in the form of increased lifetime colorectal cancer risk.
Keywords: CRC- Colorectal cancer; Smoking; Colorectal Cancer.
Cases of colorectal cancer (CRC) are rapidly increasing and affecting every nation in the world, irrespective of socioeconomic status . Because of its fatality, it has been placed 3rd on the table of common cancers. In contrast, bladder and breast cancer (male/female) took the first and second positions, respectively, making CRC a significant public health issue .
However, following the widespread incidence of colorectal cancer, there have been reports of disparities in gender and affinity for certain sides. A recent pooled analysis in Japan revealed no significant observation in a cancer specific preference for men or women or even anatomic subsites. However, involvement of the distal part of the colon was reported more often . Concerning proneness for specific sites in both sexes, more males presented with left colon cancer and women with right colon cancer .
The racial vulnerability to colorectal cancer from smoking has not received much attention due to inconsistencies in findings. However, a study done in Hawaii showed a CRC predilection for certain racial groups like Japanese and black Americans compared to Caucasians and native Hawaiians .
As a result of the morbidity and mortality associated with colorectal cancer, its survival outcome has been reported to be generally low. However, recent studies have found that all smokers, including previous and active users, had a poor success rate for survival; however, this was heavily reliant on several underlying factors like the length of cessation, as previous short-term users had a better success rate for survival compared to previous long-term users. However, those who had never smoked had an overall higher success rate than the latter [5,6]. The findings from the above study were in keeping with the results of a study that investigated the effects of smoking cessation on colorectal cancer prognosis . It was, however, found that a poor survival outcome was associated with active users of tobacco and showed a poor response to chemotherapy . In contrast, previous users responded well to therapy and had a high success rate for survival .
Several factors have been implicated in the screening process of colorectal cancer from smoking. However, biomarkers, which are biological indicators of tobacco, have been reported to be essential in identifying colorectal cancer prone individuals from smoking who present early for screening . Similarly, identifying neoplastic or nonneoplastic colon polyps during imaging screening has been reported to be adequate criteria for identifying potential colorectal cancer cases, hence instrumental in curbing its mortality .
Additionally, smoking history has been assumed to be an insufficient prognostic factor. However, a study done in the U.S. reported that a more significant percentage of men and women who were long-term users of tobacco had a higher probability of developing colorectal cancer compared to short-term users, which is in keeping with a study that reported that smoking habits and period of cessation were significant predictors of survival outcomes [10,11].
Surprisingly, the cases of colorectal cancer from the use of tobacco are still on the rise, and this may be due to advertisements on social media platforms and TV stations coexisting with other predisposing factors like lifestyle and environmental factors, hence the need for the implementation of three-tier levels of prevention .
The biological mechanism underlying the pathogenesis of colorectal cancer has not been well understood. However, several mechanisms have been postulated, including intestinal epithelial damage by carcinogens . Other mechanisms include macrophage infiltration and depressed immunity, which is with a study that showed consistent depletion of T-cells, suggesting a reduced host immunity . Likewise, another study on macrophage activity with colorectal cancer showed that M1 and M2 macrophages, which have cancer protection and promotion roles, were associated with low and high mortality, hence a significant predictor of clinical outcomes .
More recently, genetic predisposition has been linked to the pathogenesis of colorectal cancer, and it was realized that both smoking and genetic predisposition could independently influence the pathogenesis of colorectal cancer. However, a synergistic effect between both can result in a higher probability of developing colorectal cancer ; this was also in keeping with the results of a study that looked at smoking and colorectal cancer from the perspective of the interaction between genetic variants and colorectal cancer. This study reported a strong correlation between cigarette usage and colorectal cancer. However, this was facilitated by an underlying propensity of specific genetic variants .
The importance of intestinal permeability cannot be overemphasized in identifying colorectal cancer. For example, one study emphasized that carcinogens from smoking can erode the intestinal epithelium, thus leading to an influx of surrounding microflora into the intestine, which triggers a series of immune sequences .
A study was conducted in China to fill the knowledge gap between the interaction of smoking and metabolism in the predisposition of colorectal cancer. It was found that smoking and metabolic syndrome can independently raise the chances of developing colorectal cancer. However, a synergistic effect of both was associated with poor prognosis .
To conduct a comprehensive investigation, we aggregated information from a population-based study that gathered comprehensive smoking details by race and ethnicity by county in Missouri to determine the assessment of disease burden of colorectal cancer caused by tobacco use among Missourians due to the high prevalence of smoking.
Materials & Methods
This analysis included 115 counties in Missouri, and data were drawn from a population-based study in Missouri.
Details of smoking status and rates were collected through the Missouri county-level study, 2007; Missouri Vital statistics, 2007; and U.S Census Bureau, 2007. The web address for these resources is provided in table 1.
|Missouri county-level study, 2007||Smoking and tobacco. Smoking and Tobacco | Health & Senior Services. (n.d.). Retrieved October 11, 2022, from https://health.mo.gov/living/wellness/tobacco/smokingandtobacco/|
|Missouri Vital Statistics, 2007||https://health.mo.gov/living/wellness/tobacco/pdf/Smoking_and_Smoking_Related_Deaths.pdf|
|U.S Census Bureau, 2007||Bureau, U. S. C. (2021, October 28). Search results. The United States Census Bureau. Retrieved October 11, 2022, from https://www.census.gov/search-results.html?q=missouri%2Bpopulation%2B2007&page=1&stateGeo=none&searchtype=web&cssp=SERP&_charset_=UTF-8|
Table 1: Smoking details sources and website.
The total population in Missouri is 6,059,651. Whites accounted for 84.9%, while black or African Americans, 11.2%, and American Indians and Alaska Natives, 0.4%. Asians, 2.1%. Native Hawaiian, 0.1%, some other races were 0.8% while two or more races accounted for 1%.
Of the 115 counties, some had few or no black or African Americans. The smoking rate for all counties was 24.9% (Missouri county-level study). For the purpose of this investigation, we categorized the population into categories of “never smoked” and “smoker.” The entire population was also categorized into “black” and “non-black.” Finally, we used the mean smoking rate for each county to calculate the number of smokers in blacks and non-blacks, assuming that both groups smoked at the same rate.
All statistical analyses were performed using an Excel® spreadsheet using simple calculations such as addition and subtraction.
We designed a spreadsheet and entered all counties in each column of the spreadsheet. For each county, we identified the total population of non-blacks and blacks and calculated their percentage in each county from the medium for smoking rate range. We assumed that the smoking rate for the ethnic groups was equal.
We multiplied the number of blacks in each county to determine the proportion of black smokers and of non-black (all other ethnic and racial categories combined) smokers. Then, knowing the proportion of smokers in each county, we sought to identify the lifetime risk of colorectal cancer, for the entire Missouri population, which was 4.2% for nonblacks while that of blacks was 20% higher .
To determine the underlying disease burden, we multiplied the lifetime risk of colorectal cancer for blacks and whites in each county. Following previous work done on the incidence of colorectal cancer, which revealed current smokers (HR1.27;95% CI, 1.06-1.52) and former smokers (HR1.23;95% CI,1.11-1.36), the first study while the second study revealed smokers (OR1.23;95% CI, 0.99-1.52) for men and (OR,1.27;95% CI, 1.01-1.59) for women and never smokers (OR1.48;95% CI 1.12-1.96). We agreed with RR 1.25 as an average from both studies [4,10].
We multiplied RR (1.25) by the lifetime risk of getting colorectal cancer of non-black (0.042) and black smokers in each county (0.0924) .
We calculated the number of persons who developed colorectal cancer from smoking by subtracting the relative risk from the underlying risk in each county.
Lastly, we added the total number of black smokers diagnosed with colorectal cancer from smoking and nonblack smokers. We predicted 12,235 cases of colorectal cancer from smoking among Missourians.
The present study included 115 counties in Missouri, comprising 6,059,651 people.
Data was pulled from population-based studies done in 2007. Overall smoking status was evaluated based on smoked or never smoked. Out of the total population of 629,391 black people, which accounted for 11.25% of the entire Missouri population, 140,512 were smokers. In contrast, out of the Missouri population (6,059,651), nonblacks accounted for 5,430,260, representing 88.75% of the entire population. Non-black smokers were found to be 856,281, making the total population of smokers in Missouri 996,793.
Out of the non-black smokers in Missouri (856,281), 8,990 was predicted to have developed colorectal cancer from smoking. In contrast, the number of black smokers who was predicted to have developed colorectal cancer from smoking was 3,245 persons, making the total cases of colorectal cancer 12,235.
The central aim of our study was to determine the disease burden of colorectal cancer from cigarette smoking among Missourians. However, we focused on white and black populations because they were the two major ethnic groups in Missouri. In contrast, the others were combined with the white population to form a non-black category.
These data from those who smoked were modeled and suggest that 1.05% of non-black smokers in Missouri would develop colorectal cancer. In comparison, 2.31% of black smokers would develop colorectal cancer. These findings support studies from Luchtenborg et al., which reported that in the U.SA, there was a higher racial vulnerability to colorectal cancer for Japanese and African Americans than Caucasians . This may be because most of the research has been restricted to Caucasians, hence the paucity of data on other racial populations. Also, given that disparities in racial vulnerability to carcinogenesis exist, it seems possible that the degree to which racial groups develop colorectal cancer vary . The reason for this difference is not well understood, and as such, more research needs to be conducted on racial vulnerability to colorectal cancer from tobacco smoking.
The main limitation of our study was that data were drawn from a population-based study and a publicly available database. Hence there was no sufficient information on the initiation of cigarette smoking, age at diagnosis, lifestyle, diets, and identification of genetic variants, which may be an underlying factor for this vulnerability.
The main finding is that there are 12,235 cases of colorectal cancer as a result of smoking in the lifetime of the Missouri population.
I sincerely appreciate Dr. David Claborn and Mrs. Tara Stulce for their immense contribution to the success of this research.
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