Breast Cancer Radiotherapy-Associated Angiosarcoma Incidence, Survival Described

One in 1000 breast cancer survivors who receive radiotherapy go on to develop a related angiosarcoma

medwireNews: Analysis of the Netherlands Cancer Registry has helped characterise the risk and outcome of radiotherapy-associated angiosarcoma (RAAS) in women who are treated for stage I to III primary breast cancer. 

A median of 7.7 years after breast cancer diagnosis, 0.1% of the 184,823 patients given radiotherapy between 1989 and 2015 developed angiosarcoma, whereas there were no cases of angiosarcoma reported for the 111,754 breast cancer patients who did not receive radiation.  

“The present study provides the largest original series of RAAS to date (n=209) to our knowledge”, say Anouk Rombouts, from Radboud University Medical Centre in Nijmegen, the Netherlands, and co-investigators, adding that the cumulative incidence of one case per 1000 patients is “comparable” with earlier small reports in the literature. 

The cohort were aged a median of 58 years at the time of breast cancer diagnosis and older age was a significant predictor of RAAS, with a hazard ratio (HR) of 1.05. 

By contrast, patients who underwent mastectomy for their primary breast cancer were significantly less likely to develop RAAS than those who received breast-conserving treatment, with a HR of 0.22. 

The researchers say that RAAS was diagnosed a median of 8 years after breast cancer treatment. Using available data from 92.8% of the affected patients, the team determined that the majority (79.4%) underwent surgery for RAAS. A further 9.1% were treated with surgery plus radiotherapy, including hyperthermia in some cases, while 1.4% received surgery plus chemotherapy, and 2.9% had chemotherapy or radiation only. 

The 5-year overall survival rate after RAAS diagnosis was 40.5%, dropping to 25.2% at 10 years. Adding radiotherapy to surgery did not significantly improve overall survival, even after adjusting for confounding factors. 

“A beneficial effect on overall survival of the addition of [radiotherapy] to the treatment of RAAS could not be confirmed in this population-based analysis, and evidence in the literature also lacks power to draw firm conclusions”, the team writes.

“This study demonstrates that the low incidence of RAAS renders a prospective analysis practically not feasible”, they comment, suggesting instead that “[e]ntering the outcomes of RAAS into a prospective international database could be considered.” 

 

Reference 

Rombouts AJM, Huising J, Hugen N, et al. Assessment of radiotherapy-associated angiosarcoma after breast cancer treatment in a Dutch population-based study . JAMA Oncol; Advance online publication 24 January 2019. doi:10.1001/jamaoncol.2018.6643

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