Radiation-Associated Sarcoma of the Breast in a Patient With a Germline Tumor Protein p53 Mutation.

Radiation-induced sarcoma of the breast is a rare complication that is primarily treated with surgical resection but in patients with advanced disease, a multimodality treatment approach is often required. This case report discusses a 37-year-old female with a history of a pT3N3M0, estrogen receptor (ER)+, progesterone receptor (PR)+, human epidermal growth factor receptor 2 (HER2)+, right breast cancer, and a germline tumor protein (TP) p53 mutation who underwent right modified radical mastectomy, adjuvant systemic therapy, and radiation therapy, and subsequently developed a radiation-induced sarcoma. The patient is a 37-year-old female who has a history of pT3N3M0, ER/PR+, HER2+, and right breast cancer diagnosed in 2014. At the time of diagnosis, she had locally advanced disease and underwent right modified radical mastectomy followed by adjuvant chemotherapy, radiation, delayed right breast implant-based reconstruction, and left breast augmentation with mastopexy. Upon completion of adjuvant chemotherapy, she was started on hormonal therapy. In February 2020, she underwent genetic testing given her early onset of breast cancer and was found to have a germline TP53 mutation. Routine MRI for breast implant evaluation showed two irregular enhancing masses with an additional satellite lesion in the right breast. Right breast ultrasound (US)-guided biopsy revealed two separate foci of high-grade pleomorphic fibroblastic/myofibroblastic sarcoma. Further staging workup with a whole-body MRI was negative for evidence of metastatic disease. Her case was discussed in multidisciplinary sarcoma tumor board and consensus was for surgical resection. She underwent radical resection of the right chest wall masses and subcutaneous tissue, removal of right breast implant and capsulectomy, and left breast mastectomy with left breast implant removal and capsulectomy. The final pathology revealed two separate foci of high-grade pleomorphic fibroblastic/myofibroblastic sarcoma, 1.2 cm and 1.1 cm in their greatest dimensions with negative margins. Her case was re-discussed in multidisciplinary sarcoma tumor board and due to T1 size of the tumors and the negative resection margins, close surveillance with annual whole-body MRI and quarterly chest MRI imaging was recommended. In patients with a germline TP53 mutation and breast cancer, the utilization of adjuvant radiotherapy should be considered cautiously given the increased risk of radiation-associated sarcoma.