CR for lymphoma means complete remission after chemotherapy or radiation therapy, which is an acronym in English for complete-remission. Complete remission of lymph nodes is diagnosed by PET-CT examination, which means that lymphoma is diagnosed as CR after chemotherapy if there is no significant hypermetabolic uptake in the lesions before treatment and PET-CT examination is performed after chemotherapy. The achievement of CR is a key indicator for long-term survival of lymphoma. PET-CT is usually performed after two cycles of chemotherapy for evaluation, and if PR or CR is achieved, the original chemotherapy regimen will be continued, while if progression occurs, a second-line chemotherapy regimen will be required.