Increased Risk of Unknown Stage Cancer from Residence in a Rural Area: Health Disparities with Poverty and Minority Status

Objectives: Quantify risk for unknown stage cancer associated with rural residence. Methods: Logistic regression using 1994-98 invasive cancer incidence data from three states, with adjustment for individualand area-level characteristics. Results: Of all cases 59,493 (12.6%) were of unknown stage. Cancers of the prostate and lung/bronchus had highest percentage with unknown stage. Among age-gender groups, males at least 65 years of age had the greatest overall percentage of unstaged cancer. Residents of rural zip codes were at 17% increased risk of unknown stage (adjusted OR=1.17, 95% CI: 1.14 to 1.20). Risk from rural residence was greater for blacks and other races than it was for whites; increased risk from rurality was found for blacks and other races in both high-and low-poverty counties. Rurality interacted with both poverty and race to increase the risk of unstaged cancer. Conclusions: Residents of rural areas with high percentages in poverty were at increased risk for unstaged cancer. The increased risk from rurality was most marked in minorities. Unknown stage is an indicator of a health disparity that may be associated with poor health outcomes.