Inflammatory breast cancer in the Netherlands; improved survival over the last decades

Purpose: Locally advanced breast cancer (LABC) includes inflammatory breast cancer (IBC) as well as non-inflammatory LABC (NI-LABC). The aim of this population-based study was to compare the tumour characteristics, treatment and relative survival of IBC and NI-LABC patients.

Methods: Patients with either IBC (cT4d) or NI-LABC (cT4a-c) were identified from the nationwide Netherlands Cancer Registry from the period 1989-2015. In each group, patients are divided into three time periods in order to perform a trend analysis: 1989-1997, 1998-2006, and 2007-2015.

Results: IBC comprised 1.1% and NI-LABC 4.6% of all diagnosed breast cancer patients. IBC patients showed more nodal metastases (77.8 vs. 69.7%, P < 0.001) and distant metastases (39.7 vs. 34.1%, P < 0.001). IBC tumours were more often triple negative (23.2 vs. 12.8%, P < 0.001) and poorly differentiated (69.8 vs. 53.8%, P < 0.001). Trimodality therapy (neoadjuvant chemotherapy, surgery and adjuvant radiotherapy) was more often applied over time in both groups (IBC: 23.7%-56.0%-68.6%; NI-LABC: 3.7%-25.9%-43.6%; P _trend < 0.001). In IBC patients, relative 5-year survival was significantly shorter than in patients with NI-LABC (30.2 vs. 45.1%, P < 0.001). The relative survival significantly improved for IBC from 17.2% (1989-1997) to 30.0 and 38.9% for the last two time periods (1998-2006: P < 0.001; 2007-2015: P < 0.001). In contrast, survival did not significantly improve in NI-LABC breast cancer: from 44.7% (1989-1997) to 44.0 and 48.4% (1998-2006: P = 0.483; 2007-2015: P = 0.091).

Conclusions: IBC has tumour characteristics that determine its aggressive biology compared to NI-LABC. Trimodality therapy was increasingly applied in both groups, but did not improve survival in NI-LABC. Although relative survival in IBC patients has improved during the last decades, it remains a disease with a dismal prognosis.