There is a possibility of recurrence after targeted therapy, which is related to the patient’s age, condition and degree of drug resistance. 1. Age: the age and physical condition of patients after targeted therapy have certain influence on the recurrence of cancer. Generally, the physical quality of the elderly is relatively low, so the recurrence rate is higher. 2. Condition: the later the cancer stage is, the higher the recurrence rate of cancer is, the recurrence rate of small cell lung cancer is higher than non-small cell cancer, targeted therapy kills the existing cancer cells, and can not eliminate the production of cancer cells fundamentally. Even if the cancer is clinically cured by targeted therapy, it may recur in the later stage. 3. Drug resistance: If the cancer cells belong to many kinds of mutated cells, some of them do not have target-specific structure, they may escape from targeted therapy and continue to proliferate, which may cause cancer recurrence. After targeted therapy, one should go to the hospital for regular rechecks under the guidance of doctors to monitor the condition in time.