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The California Teachers Study (CTS) is an observational cohort study. In 1995-1996, 133,477 women volunteered for the CTS and agreed to provide information about their health and lifestyle. CTS researchers have continued to track these participants and have collected the following types of data.

Study Questionnaires

Participants have been asked to complete six self-reported questionnaires, which collected data on various health conditions and risk factors. 

Cancers and Other Health Outcomes


The CTS investigators regularly collect data on cancer and other health outcomes among the CTS participants.

  • Linkages with the  California Cancer Registry (CCR)  provide detailed data on diagnosed cancer, including who was diagnosed, the type of cancer diagnosed, and relevant details such as stage, grade, date of diagnosis, and tumor subtype.

  • Linkages with national and state mortality data provide data on which participants have died, the date of death, and the cause of death.

  • Linkages with the State of California also provide detailed data on inpatient hospitalizations, including data on discharge diagnoses, surgical procedures, and other coded conditions relevant to that hospitalization. 



Although biospecimens were not collected from CTS participants at the start of the study, a number of CTS projects have subsequently collected blood, saliva, and other samples. 

CTS biospecimens include:

  • Blood and saliva samples collected from a total of 16,707 CTS participants between 2013 and 2016. For each of these samples, annotation of collection conditions, transport date, and processing data is available. 

  • Approximately 8,288 blood samples collected between 2005 and 2015 for a nested case-control study of breast cancer patients and matched controls. DNA have been extracted from some, but not all, of these samples. 

  • 716 blood samples from a nested case-control study of endometrial cancer patients and matched controls; DNA have been extracted from these samples.

  • Saliva samples from 8,158 participants who participated in one of the two nested case-control studies (described immediately above) or a number of other smaller projects.

  • Another 383 blood samples, toenail samples from 284 participants, and urine samples from 977 participants in the endometrial cancer case-control study.

Green bars: # of biospecimens collected among participants with breast cancer before (pre) diagnosis

Orange Bars: # of biospecimens collected among participants with breast cancer after (post) diagnosis

X-axis: Age at which the biospecimen was obtained

Inner Y-axis: Number of biospecimens. Please note this axis is on a log scale.

Outer Y-axis: Race/ethnicity groups 

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