system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A recently published prospective cohort study of 1,000 men reports that smoking is significantly associated with higher rates of esophageal cancer. The next week, however, the journal publishes a letter to the editor in which a re-analysis of the study's data when accounting for the confounding effects of alcohol usage found no association between smoking and esophageal cancer. Which of the following statements is both necessary and sufficient to explain the change in result?
assistant
Men who drink are both more likely to smoke and more likely to develop esophageal cancer