National Cancer Institute
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Health Services & Economics Branch
Cancer Control and Population Sciences

Privacy & Confidentiality Issues:

This page links to some files in Portable Document Format (PDF).

SEER-Medicare: Variables Restricted from Routine Release & Encrypted Variables

Restricted Variables

For reasons of confidentiality, selected variables are not routinely released on the SEER-Medicare files. These variables include the patient's Census tract and ZIP code, as well as the ZIP code for physicians. Selected Census data from 1990 and 2000 for each ZIP code and Census tract have been included on the PEDSF file (see PEDSF file documentation). These variables have been slightly altered to prevent matching back to the Census data and identifying the actual Census tract or ZIP Code.

Encrypted Variables

To protect the identity of individual hospitals and physicians, the hospital numbers and Unique Physicians Identifier Numbers (UPINs) on the Medicare claims are encrypted prior to release of the data. However, investigators who want to include provider characteristics as part of their analysis may do so, as described below.

For researchers who wish to obtain hospital characteristics, NCI has created a file that includes information about hospitals that are part of the SEER-Medicare data (see the hospital file description in PDF format). The hospital identifiers on this file are encrypted and can be readily linked to the encrypted hospital numbers on the Medicare claims. This file will be made available without charge to investigators. Investigators must include a description of the use of the hospital file in their proposal requesting SEER-Medicare data.

Investigators who wish to obtain information about physician characteristics, such as demographics, medical specialty, and board certification, can arrange for the UPINs identified from the Medicare carrier data to be linked to data collected by the American Medical Association (AMA). This linkage is accomplished by sending to NCI's programming contractor, IMS, the UPINs the researchers wishes to be linked. Please e-mail the UPINs list to Bob Banks at IMS will unencrypt the UPINs and send them to the AMA's programming contractor, Medical Marketing Service. Upon completion of the linkage to the AMA data, IMS will return to the investigator a file with encrypted UPINs and the selected AMA variables. Investigators must negotiate directly with Medical Marketing Services, Inc. about the variables needed and the cost of any processing. Please direct any inquiries to:

Tom Lorge
Medical Marketing Services, Inc.
185 Hansen Court, Suite 110
Wood Dale, IL 60191
Phone: 630-477-1564
Fax: 630-350-1896


If investigators determine that restricted or unencrypted variables are an essential part of their analysis, they must submit their completed application form to the SEER-Medicare contact with a detailed justification for access to the restricted/unencrypted variable(s). A completed and signed request form and a list of people that will have access to these data must be included with the request. Once NCI supports the request for these variables, investigators must obtain permission from each of the registries prior to release of restricted/unencrypted variables for that registry. If investigators request access to the unencrypted unique physician identification number (UPIN), they will also have to secure the approval of CMS. The SEER-Medicare contact will provide investigators with contact information for the SEER registries and CMS.

Note: In order to combine multiple requests when purchasing data, the requests must have the same permissions for access to any restricted variable.

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Last modified:
15 May 2012
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