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The SEER Program and Data
Overview of SEER
The SEER Program is an epidemiologic surveillance system consisting of population-based tumor registries designed to track cancer incidence and survival in the United States. Collection of the SEER data began on January 1, 1973. The registries routinely collect information on newly diagnosed cancer patients residing in geographically defined areas.
The SEER data contain information about an incident cancer diagnosis and cancer-directed surgery and radiation therapy provided for first course of treatment. The registries collect information about all primary cancers that a person may develop. The SEER data do not capture information about surgery and radiation provided past four months of diagnosis, nor is there information about recurrence or metastasis that is detected subsequent to the initial diagnosis. For more information about the SEER program and data, please see the SEER Home Page
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SEER-Medicare Cancer Data
The cancer registry data released as part of SEER-Medicare are included in a customized file known as the SEER-Medicare Cancer file. This file is an expanded SEER Research Plus file (e.g., it includes additional information variables (e.g., on place of residence, registry-determined first course of therapy and biomarker test results) not typically released by SEER, but is limited to Medicare beneficiaries. As such, the SEER-Medicare Cancer file includes one record per tumor diagnosed among persons in the SEER database who have been matched with Medicare enrollment records. Each record includes information about the person (e.g., age at diagnosis, sex, race, ethnicity, and marital status) and the tumor (e.g., site, stage, histology, and grade). Refer to the 5-digit Site Recode Dictionary for the list of cancers available.
The SEER-Medicare 5% Cancer file includes all the same variables as the SEER-Medicare Cancer file but is a subset of tumors included in the SEER-Medicare Cancer file (e.g., only includes tumors diagnosed among Medicare beneficiaries included in the 5% sample). This data subset was created because the SEER-Medicare data files can be extremely large and challenging to analyze without large computing capabilities (e.g., servers with large processing memory and storage space). The SEER-Medicare 5% Cancer file allows for more manageable analytic file sizes (e.g., limited cohort size), particularly for questions evaluating cancer in general as an outcome. This file may also be useful to investigators examining cancer etiology.
The variables included in the Documentation for the SEER-Medicare Cancer file and the SEER-Medicare 5% Cancer file is exactly the same; therefore, only documentation for the SEER-Medicare Cancer file is provided below. Investigators should note that because the SEER program has expanded over the years to include additional cancer registries, not all variables will be available for all tumors. Tumors reported to newer registries will only have variables listed as being included in the Research Plus Limited-Field files.
- SEER-Medicare Cancer File Data Dictionary (PDF, 2.1 MB)
- SEER-Medicare 5% Cancer FAQ (PDF, 647 KB)
Note: The Massachusetts, New York, and Idaho registry data were included for the first time in the 2020 SEER-Medicare linkage and the Texas registry data were first included in the 2022 linkage. Not all variables are available for these registries. The variables that are available for these registries are indicated in the data dictionary if “Research Plus Limited-Field: Yes”. The variables that are available for these registries are also compiled in this document (DOCX, 17 KB).
SEER-Medicare Control Data
Medicare enrollment, claims, and assessment data (MDS and OASIS) are also available for a random 5% sample of Medicare beneficiaries who reside in the SEER areas.