[The Recommended Chemotherapy Duration-From the Viewpoint of Drug Resistance].

: Management of patients who have completed standard chemotherapy because of drug resistance and other causes is an important issue. Some recent clinical studies on cancer have shown evidence for treatment beyond progressive disease(PD) or rechallenge of a drug that was previously discontinued because of PD due to resistance to drugs, mostly molecularly targeted agents. In medical therapy for adult patients with cancer who desire life prolongation with an acceptable quality of life, treatment continuation beyond PD and rechallenge may be options for patients who have received a standard chemotherapy, based on patients' fairly good conditions and needs, and other solid evidence for the usefulness of these treatments.