Clinical Outcomes and Prognostic Features of Angiosarcoma: Significance of Prior Radiation Therapy.

AIMS: Angiosarcoma is a rare and aggressive malignancy with a poor prognosis. There is limited literature describing prognostic factors and guidelines for treatment. We aim to describe outcomes in angiosarcoma, including the impact of patient-, tumour- and treatment-related factors on prognosis.

MATERIALS AND METHODS: Patients with non-metastatic angiosarcoma diagnosed between 2008 and 2017 were retrospectively reviewed. Univariable and multivariable Cox proportional hazards methods were used to evaluate factors associated with locoregional recurrence, distant failure and overall survival. The Kaplan-Meier method and log-rank statistics were used to compare outcomes among patients with and without a history of prior radiation therapy.

RESULTS: The cohort included 65 patients. The median age at diagnosis was 68 years (35-93). Nineteen patients had a history of receiving prior radiation therapy at the anatomic location of their angiosarcoma. Treatment modalities included surgery (n = 19), surgery + radiation therapy (n = 12), surgery + chemotherapy (n = 8), chemotherapy + radiation therapy (n = 7) and all three modalities (n = 14). The median follow-up was 18 (2-192) months. The 2-year locoregional control, distant control and overall survival were 61.8, 63.6 and 58.9%, respectively. On multivariable analysis, a history of previous radiation therapy was associated with inferior outcomes with respect to locoregional recurrence (hazard ratio 89.67, 95% confidence interval 8.45-951.07, P < 0.001), distant failure (hazard failure 3.74, 95% confidence interval 1.57-8.91, P = 0.003) and overall survival (hazard ratio 3.89, 95% confidence interval 1.56-9.60, P = 0.003). In patients with primary angiosarcoma, the rates of locoregional control, distant control and overall survival were 72.4, 73.4 and 65.1%, respectively, compared with 31.9, 41.1 and 45.1% in patients with radiation therapy-induced angiosarcoma (P = 0.001).

CONCLUSION: Angiosarcomas that arise as a result of previous radiation therapy have worse outcomes compared with primary angiosarcomas. Although selection bias and compromise of clinical care in radiation therapy-induced angiosarcoma are partially to blame, differences in genomic profiles of the tumours need to be characterised to evaluate the underlying biological differences, as this may guide future treatment management. This study adds to the existing body of literature on angiosarcoma. Results from the current study are presented alongside previously published data to further characterise outcomes and prognostic factors on this rare and aggressive malignancy.