2.3. Central cancer registry data

We linked the data from our surveys with the central cancer registry data via previously assigned ID numbers. Respondents identified from the California Cancer Registry had to provide consent for linkage with the cancer registry data, as stipulated by the state institutional review board. Nineteen of these respondents did not provide consent, so their information was not linked with the cancer registry data. We obtained demographic and cancer-specific information from the registry data, including the date of diagnosis, stage at diagnosis (Surveillance, Epidemiology, and End Results [SEER] summary stage), and type of initial cancer treatment (e.g., surgery, radiation therapy, chemotherapy, hormone treatment, immunotherapy). Additionally, we obtained details on hormonal status related to estrogen, progesterone, and human epidermal growth factor receptor 2 (HER2).