Although self-report data on treatment for breast cancer are collected in some large epidemiologic studies, their accuracy is unknown.
As part of a population-based Breast Cancer Family Registry, questionnaires on initial breast cancer treatment and subsequent recurrence were mailed to Australian women diagnosed between 1991 and 1998. These self-report data were validated against medical records for 895 women.
The median recall period was 3.2 years, mean age at diagnosis was 44 years, and 81% of women had early-stage breast cancer. Agreement between the two data sources was very high for general questions about type of treatment (100%, 99%, 99%, and 94% for surgery, radiotherapy, chemotherapy, hormonal therapy, respectively). For more specific questions about details of each treatment received, agreement was: for radiation therapy, 96% and 99% for radiation to the breast and chest wall, respectively; for surgery, 83%, 97%, and 88% for lumpectomy, mastectomy, and lymph node dissection, respectively; for hormonal therapy, 94% for tamoxifen; and for chemotherapy, range between 76% and 93%. There was 97% agreement about whether there had been a recurrence, and agreement about the location of recurrence was at least 90% for all sites. Agreement regarding stage at diagnosis was 62%, with discrepancies mostly due to women with locoregional disease incorrectly reporting distant spread.
This self-report questionnaire can be used to collect accurate data on broad categories of initial breast cancer treatment and recurrence, and even for more detailed information on specifics of treatment and site of recurrence.