Development of treatments for ENKL. Before 2000, patients with ENKL were treated with RT alone or with the same approaches, including CHOP-like chemotherapy with or without consolidative RT, used to treat other aggressive lymphomas. Clinical trials of CCRT were initiated in the early 2000s. In the mid-2000s, a study published achieving durable remission following the use of allogeneic HSCT in patients with disseminated ENKL. In 2009, the results of 2 clinical trials of CCRT with non-anthracycline chemotherapy were published. In 2011, a report showed that l-asparaginase–containing regimens achieved excellent efficacy. Then, reports described the use of pegaspargase-containing regimens and modern RT alone in selected patients. Furthermore, immunotherapy using LMP-CTL were developed. In 2017, immune checkpoint inhibitors produced promising responses. OS following the use of a first-line therapy could potentially be inferred from the efficacy of posttreatments, such as l-asparaginase–containing chemotherapy and allogeneic HSCT. Over time, RT delivery has changed from 2- or 3-dimensional CRT to modern techniques. The dose of RT has been increased from 40 to 50 Gy, and the RT volume was also increased. Allo, allogeneic.