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Inflammatory breast cancer (IBC) is a rare clinicopathological presentation of breast cancers (BC) characterized by diffuse tumor emboli in dermal lymphatic vessels. IBC have a poor prognosis compared with non-inflammatory BC, and treatment of non-metastatic IBC usually includes neo-adjuvant chemotherapy (NACT), followed by total mastectomy and adjuvant radiotherapy (RT). This retrospective study aims to describe the clinical outcomes of non-metastatic IBC patients treated with this multidisciplinary approach

This single-center retrospective study included all women diagnosed with non-metastatic IBC between 01/2010 and 01/2018 at the Institut Curie and treated with NACT, surgery and RT. Overall survival (OS), disease free survival (DFS) and locoregional free survival (LRRFS) were calculated from time of diagnosis. Prognostic factors for patient survival were analyzed based on univariate and multivariate regressions.

113 pts were treated for a non-metastatic IBC with NACT, RT with or without surgery (Table 1). Median age was 51 yrs, 79.7% of pts had N+ tumors, median Ki67 was 40%, 60.2% had grade III tumors; triple-negative breast cancers (TNBC) represented 34.6% of cases. A large majority of pts (91.2%) received adjuvant post-mastectomy RT (Table 2) and only ten pts (8.8%) received pre-operative RT; 17 pts (15%) received concomitant chemo-radiotherapy (mostly with 5FU-vinorelbine). Surgery was conducted in all but one patient (97.3%) and usually consisted of a total mastectomy (96.5%) with an axillary dissection (96.5%). Non-pCR was observed in 76 pts (67.3%). Radiotherapy delivered a median dose of 50 Gy to the breasts or the chest wall in 25 fractions; Berg’s level I, II-III, IV and internal mammary chains were included in 21.2%, 88.5%, 89.4% and 85% of all patients respectively. While the majority were treated with 3D technique, 11 pts were treated with rotational IMRT (VMAT or helical tomotherapy).

With a median follow-up of 54 months, 5-year OS, DFS and LRRFS were 78% [CI: 70.1-86.8%], 68.1% [59.6%-77.7%] and 85.2% [78.4%-92.7%] respectively. In multivariate analysis, non-pCR was an adverse prognosis factor for OS, DFS and LRRFS; pre-operative RT was an adverse prognosis factor for OS and DFS; TNBC and N+ disease were adverse prognosis factors for OS. Radiation-related adverse events were limited to acute skin toxicity (22% of grade 2 and 2% of grade 3 dermatitis); no late radiation-induced toxicity was reported.

Table 1: patient characteristics.

Table 2: Treatment characteristics.

High locoregional control could be achieved with multidisciplinary management of non-metastatic IBC, suggesting the anti-tumor efficacy of radiotherapy in this rare but pejorative clinicopathological presentation. While comparing favorably with historical cohorts, OS and DFS could be potentially improved in the future with the use of new systemic treatments, such as PARP-inhibitors or immunotherapy.