Question

What is the exposure? What is the outcome?

Study information:

Background

The effect of tobacco smoking and alcohol drinking on esophageal cancer (EC) has never been explored in Spain where black tobacco and wine consumptions are quite prevalent. We estimated the independent effect of different alcoholic beverages and type of tobacco smoking on the risk of EC and its main histological cell type (squamous cell carcinoma) in a hospital-based study in a Mediterranean area of Spain.

Methods

We only included incident cases with histologically confirmed EC (n = 202). Controls were frequency-matched to cases by age, sex and province (n = 455). Information on prior risk factors was elicited by trained interviewers using structured questionnaires. Multiple logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals (CI).

Results

Alcohol drinking and tobacco smoking were strong and independent risk factors for esophageal cancer. Alcohol was a potent risk factor with a clear dose-response relationship, particularly for esophageal squamous-cell cancer. Compared to never-drinkers, the risk for heaviest drinkers was high [OR = 7.65 (95%CI, 3.16–18.49)]; and compared with never-smokers, the risk for heaviest smokers was elevated [OR = 5.07 (95%CI, 2.06–12.47)]. A low consumption of only wine and/or beer (1–24 g/d) did not increase the risk whereas a strong positive trend was observed for all types of alcoholic beverages that included any combination of hard liquors with beer and/or wine (p-trend<0.05).

Answer 1

Answer:

For Alcohol drinking

Exposure: Alcohol consumption

Outcome: OR = 7.65 (95%CI, 3.16–18.49) which means the odds for developing esophageal cancer for heaviest drinkers are 7.65 times compared to never-drinkers.

For Smokers

Exposure: Smoking habit

Outcome: OR = 5.07 (95%CI, 2.06–12.47) which means the odds for developing esophageal cancer for the heaviest smokers are 5.07 times compared to a non-smoker.

Association between hard liquors with beer and/or wine and developing esophageal cancer

Outcome: p-trend<0.05, there is a significant positive association between the combination of hard liquors with beer and/or wine and developing esophageal cancer.

Explanation:

In this study, we are interested to see whether there is an effect of alcohol drinking and smoking on developing esophageal cancer such that we are studying the effect of certain conditions on developing esophageal cancer. These conditions are defined as the exposure such that subjects in the study are exposed to certain conditions.

Hence to see the effect of alcohol drinking on developing esophageal cancer, alcohol drinking is the exposure, and similarly, to see the effect of smoking on developing esophageal cancer, smoking is the exposure.

The odd ratio defines whether the odds of outcome in exposed group is a risk factor. If the OR is larger value than there is a risk factor involved.