Using propensity for pre-diagnosis behavior as a predictor of cancer survival time: an example in esophageal cancer.

Background: Information on the associations between pre-diagnosis health behavior and post-diagnosis survival time in esophageal cancer could assist in choosing treatments and planning health services but can be difficult to obtain using established study designs. We postulated that, with a large data set, using estimated propensity for a behavior as a predictor of survival times could provide useful insight as to the impact of actual behavior. Methods: Data from a national health survey and logistic regression were used to calculate the propensity of selected health behaviors from participant’s demographic characteristics for each esophageal cancer case within a large cancer registry data base. The associations between survival time and the propensity of the health behaviors were investigated using Cox regression. Results: Observed associations include: a 0.1 increase in the probability of smoking one year prior to diagnosis was detrimental to survival (Hazard Ratio (HR) 1.21, 95% CI 1.19,1.23); a 0.1 increase in the probability of hazardous alcohol consumption 10 years prior to diagnosis was associated with decreased survival in squamous cell cancer (HR 1.29, 95% CI 1.07, 1.56) but not adenocarcinoma (HR 1.08, 95% CI 0.94,1.25); a 0.1 increase in the probability of physical activity outside the workplace is protective (HR 0.83, 95% CI 0.81,0.84). Conclusions: We conclude that propensity for health behavior estimated from demographic characteristics can assist in determining existence of the association between pre-diagnosis health behavior and post-diagnosis health outcomes, allowing some sharing information across otherwise unrelated data collections.