title: Is conversion therapy possible in stage IV gastric cancer: the proposal of new biological categories of classification.
abstract: Conversion therapy for gastric cancer (GC) has been the subject of much recent attention. It is defined as a surgical treatment aiming at an R0 resection after chemotherapy for tumors that were originally unresectable or marginally resectable for technical and/or oncological reasons. However, the indications for resection remain to be clarified. In the present review, we focus on the biology and heterogeneous characteristics of stage IV GC and propose new categories of classification. Stage IV GC patients can be divided based on the absence (categories 1 and 2) or presence (categories 3 and 4) of macroscopically detectable peritoneal dissemination, which has a different biological outcome compared to hematological metastasis. Category 1 is defined oncologically as stage IV but the metastasis is technically resectable. Category 2 includes a marginally resectable metastasis or patients for whom the operation would not necessarily be the best choice. Category 3 includes a potentially unresectable metastasis of peritoneal dissemination that is only macroscopically detectable. Category 4 includes noncurable metastasis with peritoneal and other organ metastasis. The indications for conversion therapy might include the patients from category 2, some patients from category 3 and a very small number of patients from category 4. The longer survival can be expected for patients corresponding to categories 1, 2 and, to a lesser extent, 3, while the treatment of other patients focuses on "care." The provision of conversion therapy for stage IV GC patients might be one of the main roles of surgical oncologists in the near future.
authors.affiliation: Department of Surgical Oncology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. kyoshida@gifu-u.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Surgical Oncology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yamaguchi
authors.affiliation: Department of Surgical Oncology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Okumura
authors.affiliation: Department of Surgical Oncology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Tanahashi
authors.affiliation: Department of Gastroenterological Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kodera
mesh_terms: D002986:Clinical Trials as Topic; D015390:Gastric Bypass; D006801:Humans; D007564:Japan; D009367:Neoplasm Staging / Q000145:classification; D010166:Palliative Care; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery / Q000628:therapy*
keywords: Adjuvant surgery; Chemotherapy; Conversion therapy; Gastric cancer; Stage IV gastric cancer