The impact of screening on cancer incidence and mortality in Missouri, USA, 2004-2013

Population-based evidence regarding impact of cancer screenings and cancer rates in Missouri is lacking. This study examined whether screenings of breast cancer, cervical cancer, and colorectal cancer impact early-stage cancer incidence and mortality in Missouri.

This is an ecological study based on county-specific estimates of selected cancer screening prevalence and early-stage cancer incidence and cancer mortality.

County-specific prevalence of clinical breast examination, mammography, Pap test, sigmoidoscopy or colonoscopy, and fecal occult blood test (FOBT) were generated from Missouri County-Level Study (2003, 2007, and 2011). County-specific crude incidence and mortality were calculated (2004-2013). Pearson's correlation and Poisson regression were used to test association between cancer rate and screening prevalence. Covariates included county-level mean age, percentage of whites, percentage with low income, percentage with less than high school education high school, percentage with no insurance, and percentage having difficulties accessing care.

In the adjusted model, 'ever had Pap test' was significantly associated with an increase of 8% in early-stage cervical cancer incidence. Having clinical breast examination or Pap test in the past was also associated with decreases in mortality by 3% and 4%, respectively, although the association was not significant for Pap test. In addition, having mammography was statistically significantly associated with early-stage breast cancer incidence, and having FOBT or sigmoidoscopy or colonoscopy was associated with decreased colorectal cancer mortality; however, magnitude for these associations was only around 1%.

This study provides ecological evidence of the effectiveness of screening services in predicting early stage cancer incidence and in reducing mortality across Missouri counties. Further incentive to promote these screenings in Missouri is needed.