HCI 5073 Module 3 Registry Data Analysis Example

Younger and Later: Using State Cancer Registry Data to Examine Colorectal Cancer in Adults Under 50 and to Plan Screening Outreach

Student Name

American College of Education

HCI5073: Public Health Informatics

Module 3 Assignment

Instructor Name

October 19, 2026

Why Registry Data

Most public health data systems sample, estimate or wait for people to seek care. A population-based cancer registry is different: it aims to record every new cancer diagnosed among residents of a defined area. White et al. (2017), describing the growth of cancer surveillance in the United States, explain that because registry data provide a census of cases, they can be used to monitor incidence at the local, state and national levels, to study patterns of treatment and to evaluate whether public health efforts are preventing cancers and improving survival. That makes registries one of the few sources that can answer questions about small areas and specific groups with confidence.

This paper examines how a composite Midwestern county health department uses its state central cancer registry to study colorectal cancer among adults younger than 50 and the stage at which cancers are found. It describes how the registry data are produced and checked, what they show, how they inform screening outreach and where their limits lie.

How the Registry Is Built

Every hospital, pathology laboratory, radiation center and many physician offices in the state are required by law to report cancer diagnoses to the central registry. Trained cancer registrars, known as tumor registrars in many hospitals, abstract each case from medical records into a standard set of data items: patient demographics and residence at diagnosis, the date of diagnosis, the tumor's primary site and histology, stage at diagnosis, the first course of treatment and, through later linkage with death records, vital status. The state registry combines reports from multiple facilities for the same patient, removes duplicates and follows national standards so that its data can be pooled with other states. It receives funding through the CDC's National Program of Cancer Registries, one of the two federal programs that support registry work alongside the National Cancer Institute's Surveillance, Epidemiology, and End Results program (White et al., 2017).

The process is thorough but slow. Because cases arrive from several sources and must be consolidated and checked, data for a given diagnosis year are usually released about two years later. The county's most recent complete year is therefore 2024.

Data Quality Standards

Registry data are unusual in public health because their quality is formally measured and certified each year. The state registry submits its data to the North American Association of Central Cancer Registries, which reviews estimated completeness of case ascertainment, the share of cases known only from a death certificate, the proportion of records missing key items such as age, sex, race and county, duplicate reports and the timeliness of submission. The state has met the association's highest certification level in each of the last ten years, which requires estimated completeness of at least 95% and very few death-certificate-only cases.

For the county's purposes, two items need closer inspection. Stage at diagnosis was recorded as unknown for about 6% of colorectal cases, and those cases were more common among patients diagnosed at small rural hospitals. Race and ethnicity were missing or listed as unknown for about 3% of cases. Both gaps matter because the county's planning depends on stage and on differences between groups.

What the County's Data Show

From 2015 through 2024, the registry recorded 1,184 colorectal cancers among county residents. Two patterns stand out. First, the share diagnosed before age 50 rose from 9% in the first half of the decade to 14% in the second, and the number of cases among adults aged 45 to 49 nearly doubled. Second, the share diagnosed at regional or distant stage, meaning the cancer had already spread beyond the colon or rectum, was higher among younger patients than among those over 50, 68% compared with 55%, likely because younger adults were not being screened and their symptoms were often attributed to other causes.

The county's patterns mirror national trends. Siegel et al. (2023), using population-based registry data, reported that the proportion of colorectal cancers diagnosed in people younger than 55 rose from 11% in 1995 to 20% in 2019, and that 60% of all new cases were advanced in 2019, compared with 52% in the mid-2000s, reversing earlier gains from screening. National findings tell the county it is not an outlier; local data tell it where and among whom the shift is concentrated.

Using the Data to Plan Screening

The registry data informed three decisions. First, they supported the county's campaign to publicize the updated national screening age. The US Preventive Services Task Force (2021) recommended screening for adults aged 45 to 49 as well as those aged 50 to 75, and the county's rising count of cases in the 45 to 49 group gave local weight to that message. Second, mapping late-stage cases by census tract of residence showed three contiguous tracts where the proportion of distant-stage diagnoses was nearly twice the county average; those tracts now receive mailed stool-based test kits through a partnership with a federally qualified health center. Third, the data provided a baseline against which the county will measure progress, using stage distribution rather than incidence, because effective screening can temporarily raise incidence by finding cancers earlier before lowering it by removing precancerous polyps.

Limits of Registry Data

Registry data have limits that any analysis must acknowledge. The two-year delay means that the county is always planning with data that predate its latest interventions. Small numbers force suppression of counts in tract-level public reports to protect confidentiality, and they make rates for small groups unstable from year to year. The registry records residence at diagnosis, not where a person lived during the decades when a cancer developed, so it cannot identify environmental or occupational causes without additional data. Most importantly for this purpose, the registry records cancers, not screening. It can show that younger adults are diagnosed at later stages, but it cannot show whether they had been offered screening, declined it or lacked insurance. Answering those questions requires other data sources.

Linkage With Other Data

Linking registry records with other data can fill some of these gaps. Linkage with hospital discharge and Medicaid claims data could show whether patients had a colonoscopy or stool test in the years before diagnosis. Linkage with death records already supports survival analysis. Survey data on screening, available only at larger geographic levels, can be compared with registry stage patterns to judge whether low screening explains late diagnosis. Each linkage raises privacy and governance questions. The state registry's data release policy requires a formal application, review by an institutional review board for identifiable data and agreements limiting how results are reported, and those steps can take months. The county has begun an application for a Medicaid linkage covering adults aged 45 to 64, which would let it test whether late-stage cases cluster among adults who were enrolled but never screened.

Conclusion

The state cancer registry gives the county a complete, certified count of colorectal cancers and shows two troubling shifts: more cases in adults under 50 and a larger share found after the cancer has spread. Those data guided outreach to the tracts most affected and set a baseline for evaluation. Their limits, including delay, small numbers, missing stage for some rural cases and the absence of screening history, point to linkage as the next informatics step, which a later module will examine alongside the tools used to present these data to the public.

References

Siegel, R. L., Wagle, N. S., Cercek, A., Smith, R. A., & Jemal, A. (2023). Colorectal cancer statistics, 2023. CA: A Cancer Journal for Clinicians, 73(3), 233-254. https://doi.org/10.3322/caac.21772

US Preventive Services Task Force. (2021). Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. JAMA, 325(19), 1965-1977. https://doi.org/10.1001/jama.2021.6238

White, M. C., Babcock, F., Hayes, N. S., Mariotto, A. B., Wong, F. L., Kohler, B. A., & Weir, H. K. (2017). The history and use of cancer registry data by public health cancer control programs in the United States. Cancer, 123(S24), 4969-4976. https://doi.org/10.1002/cncr.30905