The number of years you can live after radiotherapy for rectal cancer stage 3 is related to the general condition of the patient, the malignancy degree of the tumor and the sensitivity to radiotherapy, etc., and it is different for each patient. Rectal cancer is the most common malignant tumor of the digestive system. Currently, surgery and radiotherapy have been applied to treat rectal cancer in a more mature way, and the treatment effect is better. If patients can carry out reasonable and standardized treatment under the guidance of professional doctors, most of them can significantly improve the symptoms and prolong the survival period. If patients with stage 3 rectal cancer have better general condition, lower tumor malignancy and are sensitive to radiotherapy, they can survive for several years or even 10 years after radiotherapy. On the contrary, the survival period of patients is shorter and they may die soon. Patients with rectal cancer should pay attention to a light diet, avoid greasy and spicy food, and pay attention to rest to promote the recovery of the body.