How to diagnose and treat metastatic cervical lymph node cancer of unknown primary (II) The primary clinical goal of metastatic cervical lymph node cancer of unknown primary is to find the primary lesion, but the process of finding the primary lesion should not be too long. On the one hand, most patients cannot find the primary lesion after all examinations (including PETCT), and the literature reports that this proportion may exceed 80%, so patients and their families must be fully psychologically prepared for this result before the examination, which is an objective and realistic situation as well as scientific statistics; on the other hand, because metastatic cancer of cervical lymph nodes has been confirmed by pathology, finding the primary On the other hand, since metastatic cancer in the lymph nodes of the neck has been confirmed by pathology, it is good to find the primary lesion, but if it is not found, it should not affect the treatment, and the next treatment plan must be discussed with the attending physician. More than 90% of lymph node metastases in the head and neck are squamous carcinoma, mainly from the nasopharynx, tongue root, palatine tonsils and hypopharynx; adenocarcinoma mainly from salivary glands (parotid, submandibular and sublingual glands). Of course, the patient’s own status is also very important. Patients and their families should express their difficulties and ideas about treatment as clearly as possible, and do a careful communication. The main treatment modalities include surgery, radiotherapy and chemotherapy. The following are the principles of treatment if the primary lesion cannot be found, for reference only. If the pathological type of metastatic cancer is medium to high-differentiated squamous carcinoma, surgery is preferred, and the surgery is usually radical cervical lymph node dissection or modified radical lymph node dissection, followed by radiotherapy within 6 weeks after surgery. When the pathological type of metastatic cancer is low differentiated squamous carcinoma, the possibility of nasopharyngeal or pharyngeal lymphatic ring origin is more likely, then the first choice is radiotherapy, and if the lesion is not completely removed after radiotherapy or there is recurrence, then surgery is performed. Radical cervical lymph node dissection is also used as the surgical approach. It should be especially emphasized that the wound healing ability is poor after adequate radiotherapy, and the chance of serious surgical complications (wound infection or bleeding) is much higher than that of general surgery, so patients and their families should be prepared for this. When the pathological type of metastatic cancer is adenocarcinoma, the surgery is not limited to the removal of lymph nodes, but should also include the underlying primary lesion (e.g. parotid or thyroid gland, which should be decided by the attending physician). Post-operative radiotherapy is indicated pending the final pathology results, and is complemented by radiotherapy if multiple lymph node metastases (N2), extra-peripheral invasion of lymph nodes, or involvement of nearby vital organs or tissues are present. If distant metastases are found, such as lung, liver or bone, surgery should not be considered first, and systemic therapy such as chemotherapy and pain relief should be chosen. Of course, there are exceptions. In the case of papillary or follicular thyroid cancer, even if distant metastases are found, surgery should be aggressively performed and postoperative treatment of distant metastatic lesions should rely on nuclear therapy.