Clinically, for malignant tumors, the five-year survival rate is usually used as the criterion to judge the therapeutic effect. The first three years after receiving radical treatment is the peak period of recurrence and metastasis for most patients with malignant tumors. Once the five-year critical period has passed, although the possibility of recurrence still exists, the probability of recurrence is decreasing year by year. So for a cancer patient, if there is no recurrence within five years, the symptoms are relieved or disappear, and the normal quality of life is restored, it is considered to be cured in medicine. Nasopharyngeal carcinoma is mostly poorly differentiated squamous cell carcinoma, and radiotherapy is the first choice for clinical treatment. At present, the radiotherapy effect of nasopharyngeal carcinoma is relatively good, and the five-year survival rate is about 80%. For cancer patients, early detection and early treatment will lead to better prognosis. If it is late, the treatment effect will be worse.
