The study covered in this summary was published in Research Square as a preprint and has not yet been peer reviewed.

Key Takeaway:

• Radiation-induced sarcoma (RIS) is a rare but aggressive complication of radiotherapy, and occurs at a higher rate among patients with breast cancer than those with other solid tumors.

Why This Matters: 

• Although survival is favorable, with a 2-year disease-specific survival of 88.9%, a significant proportion of patients recur locally after maximal treatment and require salvage therapy to improve outcome.   

Study Design:  

• This is a study from McGill University in Montreal, Canada, a center specializing in sarcoma management that employs a multidisciplinary approach.

• Data were collected for 8700 patients with breast cancer treated from 2000 to 2020

• A total of 19 patients with breast RIS were identified: 11 were angiosarcomas (57.9%), 3 osteosarcomas (15.8%), 2 carcinosarcomas (10.5%), 2 undifferentiated pleomorphic sarcomas (10.5%) and 1 high-grade leiomyosarcoma (5.3%).

• All patients underwent surgery; three patients received systemic therapy, and six patients received re-irradiation as salvage treatment. 

Key Results:

• The median age at RIS diagnosis was 72 years (range 39-82) and median latency period for development of RIS was 112 months (range 53-300)

• Overall, five patients had local recurrence and one patient developed distant metastases.

• Median time to progression was 7 months (range 4-14). Progression-free survival at 2 years was 56.1% (95% CI, 37.4% – 84.4%).

• At 2 years follow-up after sarcoma diagnosis, overall survival was 88.9% (95% CI, 75.5% – 100%).

Limitations:

• Data are from a single institution and RIS is rare, so the numbers are small.

• The small numbers make it difficult to draw conclusions associated with poorer outcomes.

• Data were missing for two patients who received radiation treatment at an outside clinic.

• Only data from electronic heath records were included, potentially leaving out data on paper charts that were used in the early 2000s.

Disclosures: 

• No funding was reported.

• The authors have no relevant financial or nonfinancial interests to disclose.

This is a summary of a preprint research study, “Radiation-induced sarcomas of the breast: A review of a 20-year single-centre experience,” led by Vanessa Di Lalla, MD, of McGill University Health Centre, Montreal, Canada. The study has not been peer reviewed. The full text can be found at researchsquare.com.

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