Osteosarcoma of the sternum after radiotherapy for breast cancer in a patient with suspected hereditary cancer syndrome: a case report

Abstract

Introduction: Radiation-induced malignancies are a rare phenomenon. Post-radiation sarcoma accounts for 0·5–5·5% of all sarcomas. Adjuvant radiotherapy (RT) after surgery plays a significant role in the treatment of breast cancer. Sarcomas of the breast, chest wall, sternum, axilla or supraclavicular region have been reported as a rare complication of RT for breast cancer. Osteosarcoma (OS) of the sternal bone is a rarely reported entity. OS of the sternum secondary to therapeutic ionising radiation is an even rarer diagnosis, and no such cases have been reported in India as per our literature search. Here we report such a case of post-radiation sarcoma after breast cancer treatment—OS presenting in the sternum and both the second ribs in a young lady. Findings: Our patient developed a sarcoma within a previously irradiated field. The latent period was 7·5 years. She initially suffered from a breast carcinoma for which she underwent radical surgery in the form of modified radical mastectomy. She also received 50 Gy RT dose to the chest wall and axilla. She subsequently developed an OS of chest wall in the high-dose region of RT. Another key factor is the high possibility of familial/hereditary cancer inheritance syndrome like Li-Fraumeni in our patient. Though she was never tested for p53 mutations, her young age at first diagnosis (26 years), extremely strong positive family history and spectra of cancers affecting her first-degree blood relatives (brain tumours, leukaemia) strongly hint at the possibility of such a cancer syndrome. Retrospectively, the question certainly arises, given her young age and family history, whether this patient was a right candidate for RT even once as compared to the fact that she received radiation twice.