Exploratory Factor Analysis of Squamous Cell Carcinoma of the Esophagus in Uruguay

Abstract

In the period 1996--2004, a hospital-based, case-control study on diet and risk of squamous cell carcinoma of the esophagus was conducted in Montevideo, Uruguay. The study included 234 cases and 468 controls, frequency matched on age, sex, and residence. Factor analysis (principal components) was used to identify the major food patterns associated with esophageal cancer. The analysis of food groups led to the identification of four patterns, arbitrarily labeled as traditional, healthy, high-fat, and drinker. The traditional pattern was not associated with risk of esophageal carcinoma, whereas the healthy pattern displayed a strong inverse association with this malignancy [odds ratio (OR) 0.29, 95% confidence interval (CI) 0.17-0.48, P value for trend < 0.0001]. Unexpectedly, the high-fat foods diet was also marginally protective (OR 0.60, 95% CI 0.36-1.01, P value for trend = 0.07). On the other hand, the drinker pattern displayed a twofold increase in risk of esophageal carcinoma (OR 2.03, 95% CI 1.17-3.51, P value for trend = 0.01). The present study suggests that factor analysis might contribute to the elucidation of the contribution of diet on human cancer. Because diet represents a complex set of highly correlated exposures, dietary patterns could be more explicative of the etiology of squamous cell carcinoma of the esophagus than the traditional reductionist approach.

Dietary patterns and risk of cancer: A factor analysis in Uruguay

“…19 Also the prudent pattern was strongly protective in these studies, since loaded on fish, raw vegetables and fruits. 20,21 In this study, gastric cancer was inversely associated with the prudent pattern and positively associated with the traditional pattern. Both the drinker and Western patterns were not associated with this malignancy.…”

“…Previous studies on this cancer site through factor analysis were conducted in Sweden 20 and Uruguay. 21 Both studies showed that the drinker pattern was associated with increased risk. In fact, this finding is expected since alcohol drinking is a strong risk factor in Adjusted for age, residence, urban/rural status, education, body mass index, smoking status, years since stopping, number of cigarettes/ day among current smokers, total energy intake and all the dietary patterns.-2 Main food groups for the traditional pattern: total grains, all tubers.-3 Upper aerodigestive tract (oral cavity, pharynx, oesophagus, larynx).…”

Empirically derived dietary patterns: interpretability and construct validity according to different factor rotation methods

“…The factor rotation selected for this research was the same as those reported in previous studies on dietary pattern analysis that used factor analysis or principal component analysis: the orthogonal varimax 34,5,6,37,38,39,40 , the oblique promax 11,12,13,14,15 and direct oblimin 16,17 . In brief, the varimax is a type of orthogonal rotation that attempts to maximize the variance of squared loadings on a factor, i.e., to reduce the cross-loadings of the variables, leading to uncorrelated simple factor structures 41 .…”

“…Orthogonal rotation leads to uncorrelated factors that are considered simpler and easier to interpret 8,10 , whereas nonorthogonal (oblique) rotation, such as promax and oblimin, allow producing correlated factors which are considered harder to interpret and, for this reason, have been used less in studies involving dietary pattern analysis 11,12,13,14,15,16,17 .…”

Dietary patterns and risk of oesophageal squamous cell carcinoma: a case–control study

“…An increased risk of oesophageal squamous cell carcinoma was observed with the western pattern (high: second median v. low: first median, OR 5 10? 13, 95 % CI 8?45, 43?68). …”