Population-based study of breast cancer in older women: prognostic factors of relative survival and predictors of treatment

Background: A large proportion of women with breast cancer (BC) are elderly. However, there is a lack of information regarding BC prognostic factors and care in this population. The aims of this study were to assess the prognostic factors of relative survival (RS) among women with BC aged >= 75 years old and to identify the predictive factors of treatments administered to this population. Methods: A population-based study was performed using data from the Cote d'Or breast and gynaecological cancer registry. Women aged 75 years and older with primary invasive BC and resident in Cote d'Or at the time of diagnosis made between January 1998 and December 2008 were retrospectively selected. Prognostic factors of RS were estimated in a generalized linear model with a Poisson error structure. RS rate for the whole population was given at 5 years. Logistic regression models were used to identify the predictors of the treatments administered. Results: Six hundred and eighty-one women were included. Median age at diagnosis was 80. Comorbidities (p=0.02), pT stage (p=0.04), metastases (p=<0.001), having a family doctor (p=0.03) and hormone-receptor status (p=0.006) were independent prognostic factors of RS. The RS rate at 5 years for the whole population was 78.2%, 95%CI = [72.2-83.0]. Age, pT stage, metastases, histoprognostic SBR grade, hormone receptor status and comorbidities were frequently found to be predictors of treatment with surgery alone, hormone therapy alone, breast conserving surgery plus adjuvant therapy and mastectomy plus adjuvant therapy. Conclusions: Comorbid conditions adversely affect survival in older women with breast cancer. Moreover the results of this study showed that there are numerous predictors of the type of treatment administered, and that the most important were age and comorbidities.