For example, patients with EGFR or ALK mutations in lung cancer can be treated with oral targeted drugs. Targeted drugs can replace chemotherapy in the first line of treatment, which is not only more effective than chemotherapy, but also has less side effects than chemotherapy; once the targeted drugs are resistant, then choose chemotherapy drugs. However, if there is no genetic mutation, targeted drugs cannot replace chemotherapy, and then there is no effect with targeted drugs. There are also some targeted drugs, whose own anti-tumor effect is relatively weak, need to be combined with chemotherapy for the best effect. For example, bevacizumab, an anti-tumor angiogenesis drug for advanced colorectal cancer, often needs to be combined with chemotherapy, and rituximab, a drug for CD20-positive lymphoma, also needs to be combined with chemotherapy.