Incidence, patient characteristics and treatment patterns of early-stage triple-negative breast cancer (TNBC) in Bulgaria: A retrospective analysis based on real-world data

Breast cancer (BC) is the third most common cancer, making up 10.8% of cases in both men and women. In Bulgaria, it has the highest rates of diagnosis (23.3%) and death among women, with around 3558 new cases each year, 5–7% of which are attributed to triple-negative breast cancer (TNBC). This is lower than the global rate of 12–15%. The current 3-year non-interventional study aims to analyse newly diagnosed patients with a focus on the treatment patterns in both neo-adjuvant and adjuvant settings and to measure the time patients spent on treatment (real-world time of treatment, rwTOT) using secondary real-world data collected for other purposes. For the observed period, TNBC accounted for 5.2% of all breast cancer diagnoses, with peak ages of diagnosis ranging from 45 to 65 and 60 to 70, suggesting later-age diagnosis. Real-world data show a tendency for endocrine (letrozole, goserelin and tamoxifen) and targeted therapy (trastuzumab, pertuzumab/trastuzumab and bevacizumab) in еTNBC (early stage TNBC) patients, which is not fully compliant with the guidelines but suggests the possible presence of the so-called immunophenotypic triple-negative BC with very low expression levels of ER/PR (< 10–20%). The average rWToT for each of the years is approximately 3.60 months for adjuvant therapy and 3.6 for neoadjuvant therapy.