Radiation particle therapy for adenoid cystic carcinoma is effective! Adenoid cystic carcinoma is also known as cylindrical tumor or cylindrical adenocarcinoma. It is the second most common epithelial tumor in the salivary gland after pleomorphic adenoma. It is also the most malignant tumor. The disease develops rapidly, and local spread or distant metastasis can occur at an early stage. The tumor is prone to spread along the nerves and often presents with neurological symptoms, such as local pain, facial paralysis, tongue numbness or sublingual nerve palsy. The tumor is extremely invasive and has no boundary with the surrounding tissues. The tumor is easy to invade blood vessels and the rate of metastasis to blood vessels is as high as 40%, and the most common site of metastasis is lung. The rate of cervical lymph node metastasis is low. Because of its near 100% recurrence rate and mortality rate, clinicians are daunted by it. With the continuous improvement of modern treatment methods, comprehensive treatment has now been found to have good prospects. Surgical resection is preferred as the treatment option. The surgical design should expand the normal boundaries of surgery than other malignant tumors, and intraoperative frozen section examination is desirable to determine whether the surrounding tissues are normal. However, even so, the likelihood of complete removal of the mass remains extremely low. The extent of the lesion is completely incompatible with the systemic condition, and with metastases in both lungs, the patient may not feel any discomfort. Postoperative radiotherapy is often required to kill any tumor cells that may remain. The rate of cervical lymph node metastasis in adenoid cystic carcinoma is about 10%, but direct invasion is far more common than tumor bolus metastasis. Recurrent or advanced tumors can be treated with radiotherapy in addition to extensive resection. In some anatomical areas where surgery is not complete, postoperative radiation therapy is also required. Surgery with radiation therapy has the potential to reduce the recurrence rate. For some cases where the chance of surgery is lost, radiation therapy can also be used to control the development. Conventional radiotherapy has no ability to discriminate between cancer cells and normal cells. After repeated radiotherapy, patients may develop local radiation damage, such as oropharyngeal erosion and ulceration, restricted mouth opening, tissue sclerosis, and in the most serious cases, radioactive jaw osteomyelitis and jaw bone radionecrosis. Acute injuries that occur with radiation therapy tend to occur during or within a few months after radiation therapy.