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Wisconsin Cancer Reporting System: Information for Researchers

Data resources and documentation

WCRS data can be accessed by the Department of Health Services (DHS) data portals and query systems. Visit WCRS Statistics and Publications for publicly available data. WCRS manuals, data dictionaries, and required reportable data items are available at WCRS Reporting Requirements.

Requesting WCRS data

The Wisconsin Cancer Reporting System makes high-quality cancer registry data available for researchers as outlined by Wis. Stat. § 255.04(3)(c). Our data is currently available for diagnosis years 1995-2020 as aggregate or individual record level data requests.

Line graph representing data trends with blurred people in background

Aggregate data

Aggregate data requests include cancer incidence and mortality statistics such as case frequencies and crude or age-adjusted rates. Statistics can be broken down by selected variables such as diagnosis year, sex, race, ethnicity, and/or geographic region.

  When values are small or there is the risk of identifying an individual, suppression rules apply. For example, if results contain less than six incident cancer cases or 10 cancer deaths, those values are replaced with a "^" symbol. Additionally, aggregate requests for small geographic regions (e.g., Census tracts) are subject to Division of Public Health Data Governance Board Review.

A code system of folders lined up with color tabs on a shelf.

Individual record level

Individual record level data requests are those where each row represents an incident cancer case. These requests frequently contain personally identifiable information (PII) for persons diagnosed with a reportable cancer and are processed with additional reviews. PII can only be released for Institutional Review Board (IRB)-approved research and are subject to Division of Public Health Data Governance Board review. All researchers seeking individual record level data should familiarize themselves with the following resources:

Frequently asked questions

No, WCRS only collects data on reportable cancer cases. Generally speaking, all tumors with malignant cell types are reportable except basal cell and squamous cell carcinomas of the skin and in situ cervical cancer.

For more information about reporting requirements, manuals, and data dictionaries, visit WCRS Reporting Requirements.

For studies involving patient contact, patients who indicate they do not wish to be contacted for research purposes will be excluded from data provided to you.

WCRS is also legally restricted from releasing certain tumor-level information if it is only reported to us by a certain type of reporting facility (for example, only Veterans Affairs hospitals or facilities, or only certain out-of-state facilities). Because of this, aggregated statistics calculated from your research data set may not agree with those found in public-facing data portals and query systems, such as the WISH Cancer Modules.

Yes, but with some caveats. Wisconsin participates in the NAACCR Inter-Registry Data Exchange, so we receive Wisconsin-resident case reports from other exchange-participating central cancer registries. We also receive voluntary case reports from health care facilities in bordering states. However, the volume of voluntary reports can vary from year-to-year.

Cancer case underreporting, particularly along the Minnesota border, is a documented issue—see Wisconsin Northwestern Counties with Low Cancer Incidence Rates Due to Underreporting of Cancer Cases Treated at Minnesota Facilities. P-00243 (PDF), (03/2019).

Additionally, out-of-state voluntary reporting has important implications for certain data item completeness, like first course treatment variables. For example, if a patient in your study data was diagnosed in Wisconsin, but received chemotherapy and surgery treatments in Minnesota, we may have some diagnosis information, but there is no guarantee that we captured that treatment information.

Most individual data items are fairly easy to understand, but require the use of reference materials which can be found on WCRS Reporting Requirements. But there’s definitely a range—some data items require little explanation, while others, such as treatment data items, may require the use of multiple reference materials. Some data items may even appear simple at first, but are actually very complex because of the rules oncology data specialists use to code. This can involve things like:

  • Timing windows for classifying the first course of treatment.
  • What is and isn’t considered a treatment for central cancer registry reporting.
  • Important changes to coding rules and reporting requirements over time.

WCRS race and ethnicity data on cancer cases are collected from information available in medical records and death certificates. Some racial and ethnic populations are undercounted in cancer registries due to misclassification from incorrect or missing demographic information. To reduce misclassification, WCRS participates in national linkages and standard algorithmic improvements.

American Indian/Alaska Native populations disproportionately experience misclassification from incorrect or missing demographic information in medical forms. We coordinate with the U.S. Indian Health Service (IHS) to correct American Indian/Alaska Native cases that have been misclassified or reported as unknown. The North American Association of Central Cancer Registries (NAACCR) developed the NAACCR Hispanic and Asian/Pacific Islander Identification Algorithm (NHAPIIA) to improve coding through inference. The algorithms can be downloaded in SAS at NAACCR’s Analysis and Data Improvement Tools.

Yes. We collect data item #630, Primary Payer at Diagnosis.

This is a required field intended to document the health insurance status of a patient at the time of a cancer diagnosis to support patterns-of-care studies and other research. However, there have been numerous challenges and complications related this data item's collection. Researchers should use significant caution with this data item in study analyses.

WCRS collects select information on the first course of treatment for newly diagnosed cases. However, some first course treatment data items are less complete than others.

The growing use of oral therapies and treatment in outpatient settings has also made capturing complete treatment data challenging in recent years.

Additionally, many factors determining a patient’s treatment are not captured in WCRS data items, including patient preferences, physician recommendations, comorbidities, and proximity to treatment providers. Because of this, researchers must carefully consider possible biases and use appropriate adjustments when working with treatment data.

Last revised May 16, 2024