Dr Melissa Edwards is a general surgical trainee undertaking a PhD in Surgery on the impacts of comorbidity on breast cancer care and outcomes in New Zealand women. The co-existence of breast cancer and chronic concomitant disease/s is not uncommon. Comorbidity has significant adverse implications for the diagnosis, treatment and ultimate prognosis of breast cancer, with greater impact for ethnic minorities and those living in deprivation. The study will amalgamate 15 years of information from the Auckland and Waikato Breast Cancer Registries, amassing unique detailed data for approximately 16,000 women on treatment, recurrence and mortality. Patients will be stratified by comorbidity severity using a New Zealand developed breast cancer-specific comorbidity index – the C3 index – to determine differences in outcomes by comorbidity. The objective is to determine how inequities in treatment received impact upon survival in order to identify opportunities to improve outcomes in this high risk patient group.