Second-line treatment for non-small cell lung cancer lung cancer refers to systemic treatment after the failure of first-line treatment, including the following cases: 1. Patients whose disease has progressed after first-line chemotherapy with platinum-containing regimens; 2. First-line treatment is effective, and the patient’s disease has gained remission for a period of time, and in the regular review, it is found that the tumor has started to grow again or metastases appear elsewhere, thus receiving second-line treatment; 3. The patient’s lung tumor was surgically removed, and the patient received postoperative adjuvant chemotherapy, but relapsed soon after the chemotherapy was finished, and the follow-up treatment received at this time was also considered as second-line treatment, and the adjuvant treatment received by patients who relapsed within six months after surgery is generally regarded as first-line treatment in clinical practice. The determination of the third article is controversial in academic circles. At this stage, the proportion of patients receiving second-line treatment is increasing, mainly because the development of detection means can detect very early metastatic lung cancer patients, who are generally in very good condition after first-line treatment and can tolerate second-line treatment. More than 50% of patients are able to receive second-line therapy. There are four second-line treatment drugs recommended by the treatment guidelines, namely docetaxel, pemetrexed, Erythroxel, and Troche. There is no limit to the number of cycles of second-line therapy, and patients are encouraged to take as many cycles as possible if they can benefit from the treatment and tolerate it. The premise is to try not to compromise the patient’s quality of life. Second-line therapy is generally recommended as monotherapy, but combination regimens may also be used for patients in better general condition.