Introduction In Switzerland, breast cancer (BC) is diagnosed in around 6,000 women per year. The human epidermal growth factor receptor 2 (HER2) is overexpressed in 15-20 %. This study aims to overview the implementation of treatment strategies in the clinical routine of a Swiss Cancer Center.
Methods A retrospective data analysis of 158 patients with newly diagnosed HER2+BC between 2008-2018 at the University Hospital of Basel was performed. All statistical evaluations were done using the software R.
Results The cohort contains 70,3 % (n=111/158) patients with early BC (Stage I-IIB), 17,1 % (n=27/158) with locally advanced BC (Stage IIIA-IIIC) and 12,6 % (n= 20/158) with Stage IV disease at first diagnosis. In our cohort 89.9 % (n=142/158) were treated with HER2-targeted therapy (HTT). Surgery as initial treatment in small, node-negative tumors, was performed in 3.16 % (n=5/158). Overall 28.5 % (n=45/158) received neoadjuvant treatment (NAT) and 68.9 % (n=31/45) a HER2 dual blockade plus chemotherapy. A pathological complete response (pCR) was achieved in 57.8 % (n=26/45) with NAT and 70.8 % (n=17/24) of node-positive patients were node-negative after NAT. Palliative treatment (PT) with HTT was conducted in 95 % (n=19/20).
Conclusion Trastuzumab was approved for PT of HER2+BC in 1999 and for adjuvant treatment in 2006. Dual HER2 blockade with Pertuzumab and Trastuzumab was authorized in 2013 for metastatic BC and expanded to NAT for locally advanced HER2+BC in 2016. New HTT such as TDM1 were introduced for PT and recently for patients with non-pCR after NAT. Awareness of current guidelines helps improving patient’s individual care and balance under-/overtreatment.
