Strictly speaking， “conversion therapy” is not a clearly defined word in the treatment of gastric cancer. The most important mode of treatment for gastric cancer is surgical removal (be it by endoscopic， laparoscopic or open approach)， and the outcome of a subset of patients who are not treated by surgery with curative intent is dismal. Most patients with stage IV gastric cancer fall into this category and are not indicated for surgery. However， there are occasions when the metastatic lesions that had been the reason for being classified as Stage IV respond extremely well to the chemotherapy. Since disappearance of the primary lesion is a rare event， patients with complete or near-complete response in the metastatic sites could be consulted for surgery， and this type of surgery is often referred to as a “conversion surgery”. 

 

Since chemotherapy is given before surgery， the term “conversion surgery” is often confused with surgery after the neoadjuvant chemotherapy. Neoadjuvant chemotherapy is delivered to patients under strict eligibility criteria， usually in a clinical trial setting in the Far East， and surgery after chemotherapy is， in principle， preplanned. On the other hand， conversion surgery is indicated only for a fraction of patients who undergo chemotherapy for unresectable gastric cancer. An oncologist who delivers chemotherapy to patients with unresectable gastric cancer will occasionally come across some patients who respond exceptionally well to the chemotherapy， as a consequence of which he or she may present the case in a cancer board meeting to see how surgeons react. However， the criteria to “convert” the treatment from chemotherapy to surgery have not been decided， nor is there any rationale to perform surgery for these responders. What can be said， at this moment， is that the more strict the criteria for proceeding to surgery， the better the outcome. Surgeons should resist the urge to operate on these patients unless the response to the chemotherapy is exceptional， but the speaker cannot deny the fact that there are some cases in which surgery may seem worthwhile. In this session， some case series from the literature and from the speaker’s institution will be presented and indication for this type of surgery and the extent of resection to be performed will be discussed with the participants.