Radiation-Associated Sarcomatoid Breast Tumor 12 Years After Breast-Conserving Therapy: A Case Report From the Caribbean

Radiation-associated malignancies are rare but serious late complications of radiotherapy.Radiationinduced sarcoma is traditionally defined by Cahan's criteria, i.e., origin within a previously irradiated field, a latency period exceeding five years, development from previously normal tissue, and histological distinction from the primary malignancy.We report a rare radiation-associated sarcomatoid malignancy of the breast in a Caribbean patient.A 65-year-old woman presented with a rapidly enlarging breast mass 12 years after being treated with breast-conserving surgery, axillary clearance, adjuvant radiotherapy and endocrine therapy for stage I, hormone receptor-positive, invasive ductal carcinoma of the left breast in 2013.Imaging demonstrated a large, necrotic lesion with chest wall involvement and no distant metastases.Core biopsy revealed a high-grade sarcoma.Immunohistochemistry was largely negative for epithelial and mesenchymal markers, with a high proliferative index (Ki-67: 40%).The patient underwent radical mastectomy, and the final histopathological examination demonstrated a grade 3 sarcomatoid tumor with clear margins.Given its development within a previously irradiated breast after a 12-year latency, a radiation-associated malignancy was considered.Complete surgical resection with negative margins remains an important component of management of localized radiation-associated sarcomatoid malignancies.The role of adjuvant systemic therapy and re-irradiation remains unclear and should be individualized through multidisciplinary discussion.Radiation-associated malignancies, although rare, should be considered in patients presenting with new breast masses years after radiotherapy.Early recognition and prompt evaluation are essential to facilitate curative management.This case highlights the importance of long-term survival and multidisciplinary care in breast cancer survivors.