The distributions of sociodemographic and anthropometric characteristics, as well as smoking, alcohol use, and total energy intake, by case-control status are given in . The average ages among the case and control subjects were 58.8 years and 61.6 years, respectively. Slightly more cases than controls were black (23.3% cases, 18.9% controls) and male (76.5% cases, 69.0% controls), while fewer cases (15.1%) than controls (31.2%) were college graduates. Liquor and beer intake and smoking were much more common among cases than among controls, reflecting the importance of these variables in the etiology of head and neck SCC. Total energy intake was also greater among the cases. Cancers of the oral cavity and pharynx accounted for the majority of the cases.
Distribution of Sociodemographic and Anthropometric Factors Among Cases With Head and Neck Squamous Cell Carcinoma and Controls, CHANCE Study, North Carolina, 2002–2006
The first 2 derived factors explained over half of the variation in the data (53.6%) and yielded meaningful interpretations. The remaining variability in dietary intake was spread across the other 70 factors, with no discernable pattern to the factor loadings. For the 2 patterns used in this analysis, rotated factor loadings with absolute values greater than 0.20 for the individual food items are presented in . The first factor, explaining 27.0% of the variation in the data, loaded highly on fruits (bananas; strawberries; fruit salad; apples, pears, and applesauce; grapes, peaches, and cantaloupes; oranges and grapefruit), vegetables (carrots; string beans; cooked spinach, turnip greens, and collard greens; zucchini and squash; broccoli and cauliflower; salad), and sources of lean protein (light-meat chicken, not fried; seafood, not fried) and was deemed the “fruit, vegetable, and lean protein” pattern. The second pattern, explaining 26.6% of the variation, which we call the “fried foods, high-fat and processed meats, and sweets” pattern, loaded highly on beef (roast beef, burgers, ground beef), fried chicken (dark and light meat), candy and chocolate, ice cream, desserts, sugar-sweetened beverages, sausage and bacon, pork products, hash and Spam (Hormel Foods Corporation, Austin, Minnesota), bologna and ham, and fried seafood.
Rotated Factor Loadings for Food Items, CHANCE Study, North Carolina, 2002–2006a
The fruit, vegetable, and lean protein pattern was associated with decreased risk of head and neck SCC overall (), with decreasing risk being observed across increasing levels of intake (for quartile 4 vs. quartile 1, odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.39, 0.71) and a significant linear trend (P < 0.0005). Although the association between the highest intake of this pattern and oral and pharyngeal cancer (OR = 0.45, 95% CI: 0.32, 0.63) was somewhat stronger than for laryngeal cancer (OR = 0.73, 95% CI: 0.48, 1.10), this heterogeneity of effect failed to reach statistical significance (P-heterogeneity = 0.24).
Risk of Head and Neck Cancer According to Quartile of Dietary Pattern (Determined Among Control Subjects), Overall and by Cancer Site, CHANCE Study, North Carolina, 2002–2006
In contrast, the dietary pattern characterized by fried foods, high-fat meats, and sweets was associated with an increased risk of head and neck SCC (OR = 1.24, 95% CI: 0.84, 1.82; P-trend = 0.02). The elevated risk for this dietary pattern was essentially limited to laryngeal cancer (OR = 2.12, 95% CI: 1.21, 3.72), because a nearly null relation was observed when oral and pharyngeal cancers were considered (OR = 0.96, 95% CI: 0.63, 1.47; P-heterogeneity = 0.05).
As shows, the pattern characterized by high fruit, vegetable, and lean protein intake showed similar effects regardless of prediagnosis body mass index (P-interaction = 0.24), gender (P-interaction = 0.28), smoking duration (P-interaction = 0.18), liquor consumption (P-interaction = 0.99), and beer consumption (P-interaction = 0.50). Although an inverse association of this pattern with head and neck SCC risk was noted among all participants, the effect of higher intake appeared to have more reduced odds among black subjects (OR = 0.28, 95% CI: 0.14, 0.59) than among white subjects (OR = 0.58, 95% CI: 0.42, 0.81; P-interaction = 0.14); however, this difference was not statistically significant. Linear trends were significant within strata of each of the effect modifiers considered here.
Table 4. Effect Modification of the Association of the Fruit, Vegetable, and Lean Protein Dietary Pattern With Risk of Head and Neck Squamous Cell Carcinoma by Anthropometric, Sociodemographic, and Lifestyle Factors, CHANCE Study, North Carolina, 2002–2006 (more ...)
Although the interactions concerning the fried foods, high-fat and processed meats, and sweets pattern did not meet the criteria for heterogeneity, several patterns emerged. This pattern appeared to be more strongly associated with head and neck SCC risk among overweight persons (; OR = 1.70, 95% CI: 1.10, 2.62), with a nearly null effect being seen among those who were not overweight (OR = 0.89, 95% CI: 0.52, 1.52; P-interaction = 0.13). The association between high consumption of fried foods, high-fat meats, and sweets and cancer was stronger among blacks (OR = 1.92, 95% CI: 0.81, 4.58) than among whites (OR = 1.31, 95% CI: 0.88, 1.95) and stronger among persons who had smoked for a longer amount of time (for never smokers, OR = 0.97 (95% CI: 0.54, 1.75); for those who had smoked for <1–19 years, OR = 1.20 (95% CI: 0.60, 2.41); for those who had smoked for ≥20 years, OR = 1.94 (95% CI: 1.23, 3.07)). A stronger association was also noted for decreasing intake of beer (for 0 drinks/day, OR = 1.82 (95% CI: 1.01, 3.30); for <1–4 drinks/day, OR = 1.28 (95% CI: 0.75, 2.17); for ≥5 drinks/day, OR = 1.02 (95% CI: 0.60, 1.76)), but a similar pattern was not evident for liquor consumption. Linear trends were significant among overweight persons (P-trend = 0.004), males (P-trend = 0.01), long-term smokers (P-trend < 0.0005), persons consuming 5 or more liquor-based drinks per day (P-trend = 0.002), and persons who consumed no beer (P-trend = 0.005).
Table 5. Effect Modification of the Association of the Fried Foods, High-Fat and Processed Meats, and Sweets Dietary Pattern With Risk of Head and Neck Squamous Cell Carcinoma by Anthropometric, Sociodemographic, and Lifestyle Factors, CHANCE Study, North Carolina, (more ...)
The effect of dietary pattern was similar within cancer site (oral/pharyngeal vs. laryngeal) for most variables (data not shown), with the exception of race (P-interaction = 0.005). For oral and pharyngeal cancer, a stronger effect of the fruit, vegetable, and lean meat pattern was more evident among blacks (for quartile 4 vs. quartile 1, OR = 0.38, 95% CI: 0.19, 0.75) than among whites (OR = 0.54, 95% CI: 0.37, 0.78).