SECTION C

This part of the exercise is based on a 2001 nation-wide case-control study of adenocarcinoma of the esophagus in Sweden, a country with approximately 9 million inhabitants. (Source: Terry P, Lagergren J, Hansen H, et al. Fruit and vegetable consumption in the prevention of oesophageal and cardia cancers. Eur J Cancer Prev. 2001; 10(4):365-9.) The data for the exercise were provided by the first author.All cases of esophageal adenocarcinoma that occurred in Sweden during a three-year study period were enumerated and 185 were willing to participate in a study of diet and other potential risk factors for this disease. Also included in the study were 1,123 control subjects who were selected randomly using nationwide population registers.

Servings / Day N Cases N Controls

Lowest quartile level <2 67 280

Second quartile level 2 to < 3 56 281

Third quartile level 3 to < 4 33 281

Highest quartile level > 4 29 281

C.1. Define three servings of fruits and vegetables per day or more as "high" exposure and anything less than three servings per day as "low" exposure. Name, calculate, and interpret the appropriate measure of association between LOW level of fruit consumption and esophageal cancer in this study. Based on these data what is the prevalence of low fruit consumption level in the general population of Sweden?

C.2. What proportion of esophageal adenocarcinoma cases among low vegetable and fruit consumers is attributable to low consumption of fruits and vegetables? Name, calculate and interpret the appropriate measure.

C.3.What proportion of esophageal adenocarcinoma cases in the study population is attributable to low consumption of fruits and vegetables in Sweden? Name, calculate and interpret the appropriate measure.