SEER-Medicare: Changes in the 2020 Linkage

The 2020 SEER-Medicare linked data are not compatible with any previously released data.

As a result of new agreements with the Centers for Medicare & Medicaid Services (CMS), all Medicare data that will be included in SEER-Medicare (including years of data released in prior linkages) will come from CMS’s Chronic Conditions Warehouse (CCW). As such, the Medicare data that will be included in SEER-Medicare moving forward will be the exact same files (e.g., same variables and file layouts) that are available directly from CMS; NCI will make only minimal modifications to the CCW files to maintain adherence to established SEER-Medicare policies (e.g., encryption of ZIP codes and provider identifiers). Please note, data files are available from the CCW starting in 1999; as a result, starting with the 2020 linkage update, the first year of data available in SEER-Medicare will be 1999.

NCI believes that the above changes will be beneficial and will lead to increased consistency across all users of Medicare data; therefore, NCI is excited for all SEER-Medicare users to start using the CCW files. Researchers who have open SEER-Medicare projects will be able to complete their studies using the data files that they currently have for as long as their DUAs are valid. However, to not prolong the complete switch to the CCW files, researchers will not be allowed to request new CCW files to combine with older files that they previously received. If additional data are required to complete an open project, an entirely new request can be made via usual processes.

In an additional effort to make the data released via SEER-Medicare more consistent with what is released directly from CMS, the PEDSF file will be discontinued starting with the new data release. Instead two files will be made available: 1.) the SEER File, which will include tumor-level cancer data (e.g., site, stage, histology, date of diagnosis) and 2.) the Master Beneficiary Summary File (MBSF), which will include person-level Medicare entitlement and enrollment information. This change will also mean that the number of tumors per person will no longer be truncated.

Finally, improvements were made last linkage to SEER-Medicare (e.g., incorporation of the Minimum Data Set and the creation of Cancer Medication Enquiry Database; as detailed in a JNCI supplement). NCI is now excited to announce addition enhancements that will be included with the upcoming linkage update. Namely, additional Part D data will be made available, including the Pharmacy and Prescriber Characteristic Files and the Formulary File. The availability of these files will allow researchers to further investigate factors associated with oral medication utilization. Three new SEER registries will also be included in the linkage update: Idaho, Massachusetts and New York. Although cancer cases diagnosed back to 2000 will be included in SEER-Medicare from these registries, because the registries collected the data prior to becoming SEER registries, all variables included in the SEER File will not be available (click here for more details (PDF)External Web Site Policy).

NCI recognizes that it will take some time for SEER-Medicare users to understand and adapt to these file format changes. New file documentation will be provided on the SEER-Medicare website and with all SEER-Medicare data that is shipped to approved requestors. However, we believe that harmonization with the CCW will ensure more consistent use of CMS data for research purposes.

Last Updated: 10 Dec, 2020