Dietary patterns and risk of oral cancer: A factor analysis study of a population in Jakarta, Indonesia
Introduction
Oral cancer is one of the most common cancers worldwide.1 Tobacco smoking, alcoholic consumption and betel quid chewing have been found to be major risk factors. Besides that, epidemiological studies have shown that diet plays a role in many chronic diseases and various types of cancer including oral cancer.2, 3 The American Institute for Cancer Research4 estimated that diet could account for approximately 30% of cancer deaths in United States, similar to the number accounted for by smoking.4 The World Health Organization acknowledges that up to 30% of human cancers are probably related to diet and nutrition.5
Most of the epidemiological studies of diet in relation to oral cancer have been conducted in western countries while studies on food and dietary pattern and risk of oral cancer are scarce in the Asian regions. So far only three studies have been reported in Asian countries regarding the food and diet pattern in association with oral cancer.6, 7 The most consistent findings in diet as determinant of cancer risk is the association between consumption of vegetables and fruit in reducing risk of several cancers. About 80% of these studies found a significant protective effect of overall consumption of vegetables and/or fruit or at least of some types of vegetables and fruits.8, 9, 10, 11, 12
Studies to determine the relationship between diet and oral cancer presents a challenge due to the complexity of the human diet. Such complexity arose from the fact that food may contain chemical compounds which are well-known for some, while many could not be measured and is still poorly characterized. However, most of these studies are confined to single aspect of food type where the interaction of each food type may not be taken into account. More recently, several researchers have introduced a new alternative approach in analyzing the dietary pattern and risk of oral cancer.13, 14 This approach is called factor analysis which uses the correlation between food and nutrient intake to describe a general dietary pattern which at a later stage may be related to the risk of oral cancer. The factor analysis also values the effect of the diet which is not mediated by one or two specific nutrients, but by nutrients that perhaps operate interactively.15 To date there is no report in the English literature on factor analysis for oral cancer in the Asian region. The purpose of this study was to determine the association between dietary pattern and oral cancer in a Jakarta population using factor analysis.
Section snippets
Subjects
A case-control study of oral cancer was conducted in five hospitals in Jakarta from January 2005 to April 2006. Cases were subjects with incident cancer, histologically confirmed as squamous cell carcinoma of the oral cavity (C00–C06) excluding salivary gland, pharynx and nasopharynx (C07–C11) (International Classification of Disease 10th Revision). A total of 81 eligible cases aged 23–74 years (mean age 47.4 years ± 12.4) were included and interviewed using a structured questionnaire which had
Results
The sociodemographic characteristics of subjects are as presented in Table 2.
This study showed the KMO of 0.671 (more than 0.600) and the Bartlett’s test of sphericity of 0.000 (less than 0.05), making the sample of this study adequate for factor analysis. Four principle factors/components were retained through factor analysis (Table 3), based on KMO and Scree plot where the eigen value was more than 1 (Fig. 1). The first factor/component, which accounted for 27% of the total variance, is
Discussion
In the present study, the dietary pattern was explored in oral cancer subjects from five hospitals in Jakarta, Indonesia and matched controls. Four components named preferred, combination, chemical related and traditional which explained 55% of the variability within the samples was identified. The factors/components identified were then used as co-variables in determining whether the effect of specific nutrient is independent of the dietary pattern.
The first factor/component identified as
Conflict of Interest Statement
This project has no conflict of interest with any institution that supported my project.
Acknowledgement
This study was supported by research grants from Trisakti University, Indonesia (no. 0769/Usakti/bsdm/db/10/2004) and University of Malaya (F0150/2005A). We thank Dr. Nugroho Abikusno (Medical Faculty University of Trisakti, Indonesia) and Dr. Cheong Sok Ching (Cancer Research Initiative Foundation, Kuala Lumpur) for their advice.
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