Short summary

This is a nationwide observational cohort study to investigate treatment efficiency, risk of relapse and overall survival amongst women treated with preoperative medical treatment for early breast cancer in Denmark from 2011 to 2021. The cohort study will include register data from five different national registries and clinical databases.

Rationale

Approx. 5000 new cases of breast cancer are reported in Denmark each year. The incidence has been stable over the past years and survival has improved over the last decade with a current overall 5-year survival of 90%. More than 90% of cases are considered curable at the time of diagnosis, the treatment strategies are comprehensive and effective, and new treatment options are continuously being developed. Patients with a high risk of relapse are offered preoperative treatment to improve prognosis and surgical outcome. However, considering the high survival rate, presumably some patients are receiving excessive treatment with a very high risk of unnecessary side and late effects. Therefore, there is a need for more sensitive methods to stratify patients to the optimal treatment strategy. This study aims to evaluate on real world data from a true population of the effects of neoadjuvant treatment of breast cancer in Denmark to identify subgroups of patients of high clinical relevance for better monitoring methods.

Description of the cohort

Patients with a first registration in the Danish Breast Cancer Group (DBCG) clinical database of local or local advanced breast cancer between January 1 2011 and December 31 2021 with allocation to neoadjuvant treatment.

Data and biological material

Demographic and clinical data from DBCG, the National Patient Registry, the Central Person Register, the Danish Pathology Register and the Cause of Death Register.

Collaborating researchers and departments

Department of Oncology, Vejle Hospital

• Else Maae, MD, PhD
• Torben Frøstrup Hansen, Professor, MD, PhD
• Signe Timm, Biostatistician, PhD

Department of Clinical Biochemistry

• Line Nederby, Molecular Biologist, PhD