Introduction/Background*Radiation associated angiosarcoma of the breast (RAAS) is a rare aggressive post-radiotherapy complication with an estimated incidence of 0.05-0.3%. Currently, there is minimal evidence on presentation, outcome and factors affecting the likelihood of recurrence and survival.

Methodology All patients diagnosed with RAAS, managed at the Birmingham Sarcoma Service (Birmingham, UK) between February 2013 and March 2021 were identified. Full clinical, pathological and patients’ outcome data were collected. The non-parametric Mann-Whitney U test was used to test statistical significance and receiver operating characteristic (ROC) curve was utilised to determine threshold values.

Result(s)*A total of 53 patients fulfilled inclusion criteria. Their previous breast cancer diagnosis spanned from 1982-2004. The median age at diagnosis was 71 years (range 56-93). The median interval from radiotherapy to RAAS diagnosis was 8 years (range 1-37years). This interval has significantly shortened over the years (p<0.001). Sixteen patients (30%) developed recurrent RAAS and 19 patients (36%) died of the disease. The overall 5-year survival was 52.5%.

Distance to resection margin was found to be highly significantly different (p=0.002) between patients who had no recurrent RAAS (median clearance 16 mm) and recurrent disease (median clearance 6 mm). The threshold margin where recurrence was less likely to occur was 7.5mm (area under the curve (AUC)=0.769, sensitivity 82.9%, specificity 56.5%).

Tumour size was significantly larger (median 102.5mm) in those patients who died compared to those who survived (median size 42.5mm; p=0.02). Patients with tumour sizes greater than 47.5mm were more likely to die from the disease (AUC=0.701, sensitivity 81.3%, specificity 56.2%). Neither patient age nor grade of the angiosarcoma correlated with lesional recurrence or patient outcome.

Conclusion*RAAS is associated with high likelihood of recurrences and mortality. Tumour size and margin status are significant predictors of recurrences and patient survival. Over the last decade, the number of diagnosed cases has increased with a shortening in the interval between radiotherapy and onset of RAAS. Due to the rarity and aggressiveness of the disease , management of RAAS at a specialist centre may provide superior outcomes.