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World J Clin Oncol. Dec 10, 2014; 5(5): 973-981
Published online Dec 10, 2014. doi: 10.5306/wjco.v5.i5.973
Radiation-induced sarcomas of the head and neck
Anuradha Thiagarajan, N Gopalakrishna Iyer
Anuradha Thiagarajan, Department of Radiation Oncology, National Cancer Centre Singapore, Singapore 169610, Singapore
N Gopalakrishna Iyer, Department of Surgical Oncology, National Cancer Centre Singapore, Singapore 169610, Singapore
Author contributions: Thiagarajan A and Iyer NG conceived, wrote and edited this manuscript.
Correspondence to: Dr. N Gopalakrishna Iyer, MD, PhD, Department of Surgical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore. gopaliyer@yahoo.com
Telephone: +65-64368294 Fax: +65-62257559
Received: June 2, 2014
Revised: August 28, 2014
Accepted: October 14, 2014
Published online: December 10, 2014
Processing time: 191 Days and 23.3 Hours
Abstract

With improved outcomes associated with radiotherapy, radiation-induced sarcomas (RIS) are increasingly seen in long-term survivors of head and neck cancers, with an estimated risk of up to 0.3%. They exhibit no subsite predilection within the head and neck and can arise in any irradiated tissue of mesenchymal origin. Common histologic subtypes of RIS parallel their de novo counterparts and include osteosarcoma, chondrosarcoma, malignant fibrous histiocytoma/sarcoma nitricoxide synthase, and fibrosarcoma. While imaging features of RIS are not pathognomonic, large size, extensive local invasion with bony destruction, marked enhancement within a prior radiotherapy field, and an appropriate latency period are suggestive of a diagnosis of RIS. RIS development may be influenced by factors such as radiation dose, age at initial exposure, exposure to chemotherapeutic agents and genetic tendency. Precise pathogenetic mechanisms of RIS are poorly understood and both directly mutagenizing effects of radiotherapy as well as changes in microenvironments are thought to play a role. Management of RIS is challenging, entailing surgery in irradiated tissue and a limited scope for further radiotherapy and chemotherapy. RIS is associated with significantly poorer outcomes than stage-matched sarcomas that arise independent of irradiation and surgical resection with clear margins seems to offer the best chance for cure.

Keywords: Post-irradiation; Nasopharyngeal carcinoma; In-field; Radiotherapy; Head and neck cancer

Core tip: Radiotherapy is an important modality in the curative management of head and neck carcinoma. However, it is also associated with significant morbidity. Radiation-induced second malignancies, particularly radiation-induced sarcomas (RIS), are arguably the most devastating sequelae associated with radiotherapy. This review examines the common trends, pathophysiology, clinical presentation, diagnosis and management of RIS in head and neck cancers.