Higher relative survival in breast cancer patients treated in certified and high-volume breast cancer centres - A population-based study in Belgium

Objectives: The study was undertaken to assess the association between certification and volume of breast centres on the one hand and survival on the other in patients with invasive breast cancer (IBC). Methods: The study comprises a cohort of 46,035 patients diagnosed with IBC between 2014 and 2018, selected from the nation-wide Belgian Cancer Registry (BCR) database, which was linked with health insurance, hospital discharge and vital status data. Overall and relative survival probabilities were obtained with Kaplan-Meier method and an actuarial approach based on Ederer II, respectively. The associations between centre certification/volume and relative survival were assessed using Poisson models, adjusted for potential confounders. Results: Five years after the diagnosis of IBC, the observed and relative survival probabilities for the cohort were 83.4 % (95 %CI: [83.1, 83.8]) and 93.3 % (95 %CI: [92.9, 93.7]), respectively. After adjustment for age and combined tumour stage, the risk to die from BC was 44 % higher (EHR: 1.44, 95 %CI: [1.24, 1.66]) for patients treated in a low-volume centre and 30 % higher (EHR: 1.30, 95 %CI: [1.14, 1.48]) for patients treated in a medium-volume centre, compared to high-volume centres. Likewise, the risk to die from BC was 30 % higher (EHR: 1.30, 95 %CI: [1.15, 1.48], p < 0.001) for patients treated in a non-certified centre (representing 23.8 % of the cohort), compared to patients treated in a coordinating breast clinic. Conclusion: This population-based study reveals that BC survival is higher when patients are treated in certified and high-volume breast clinics.