Carbon Ion Radiotherapies for Adenoid Cystic Carcinoma

Adenoid cystic carcinoma (ACC) is a rare tumor accounting for approximately 1% of all malignant tumors in the salivary gland tissue of head and neck. The main clinical treatment of ACC was depended on surgical operation in the past. Those patients with operable ACC have better clinical outcomes after surgery. However, as ACC cannot be completely excised by surgery, the residual of tumor cells is the independent risk factor for the recurrence of ACC. Therefore, radiotherapy was usually used after the operation. However, ACC is a disease resistant to radiation. Comparing to conventional proton beam, carbon ion radiotherapies have better radiophysical features, biological properties and beneficial for tumor control and protection of normal tissues. There are many carbon ion therapy centers worldwide, mainly in Japan, German, America and Shanghai of China. The treatment methods include carbon ion radiotherapy only, combined carbon ion radiotherapy with intensity-modulated radiotherapy (IMRT), carbon ion radiotherapy for recurrent ACC, pediatric patients and young adults with ACC. In addition, combined carbon ion radiotherapy with targeted drug remains ongoing. The effectiveness and safety of carbon ion have been confirmed in those researches.