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Cancer Network (NCCN) guidelines for gastric cancer also recommended the doublet or triplet platinum/
[3]
fluoropyrimidine combinations for metastatic gastric cancer as a palliative chemotherapy.

Recent advances in chemotherapy and molecular targeted therapy have been remarkable, and some patients
have survived for long periods. Some of these patients include those who have successfully undergone
curative resection after chemotherapy. However, the significance of surgical resection after chemotherapy,
termed conversion surgery, remains controversial for patients with gastric cancer.

Factors that make curative resection impossible include tumor invasion to adjacent structures (T4b), extensive
nodal disease (para-aortic and/or bulky lymphnode metastasis located on supra-pancreatic area), hepatic
metastases, peritoneal dissemination, peritoneal cytology positive for cancer cells, and other metastatic
disease. The treatment strategies and outcomes differ according to each noncurative factor. In this chapter,
we review the treatment outcome of conversion surgery for each type of unresectable advanced gastric
cancer.

TREATMENT STRATEGIES AND OUTCOMES FOR CONVERSION SURGERY
Lymph node metastases
Para-aortic lymph node metastases from gastric cancer are classified as M1, and surgery with curative intent
is not indicated according to the treatment algorithm of the current guidelines . In addition, a standard
[1]
treatment strategy including a role for para-aortic lymph node dissection (PAND) in patients with more
advanced nodal disease has not yet been established. Systemic PAND was attempted in clinical studies in
Japan until its survival benefit was denied in a randomized trial in which only patients without lymph node
[4]
swelling in the para-aortic region were eligible . Based on the results of that study, prophylactic PAND for
patients with no signs of para-aortic lymph node metastasis was discontinued. However, no prospective
study has either supported or opposed PAND in patients with surgically resectable para-aortic lymph node
metastases at station numbers 16a2-b1.

Tokunaga et al. retrospectively analyzed 178 patients who underwent R0 resection and were found to have
[5]
metastasis to the para-aortic lymph nodes after examination of the resected specimens. Of these patients,
50 were treated by D2 gastrectomy plus PAND and 128 were treated by D2 with sampling of para-aortic
nodes that were suspected to have cancer involvement. The 3-year survival rate was 21%. Perioperative
chemotherapy was administered at the physicians’ discretion but was not consistently delivered throughout
the series. The authors concluded that D2 gastrectomy + PAND could be beneficial for carefully selected
patients with metastasis to the para-aortic lymph nodes.

The effectiveness of PAND for patients with para-aortic lymph node metastases was shown in phase II trial
by the Japan Clinical Oncology Group (JCOG) (JCOG0405). The treatment strategy was as follows. Two
courses of neoadjuvant chemotherapy with S-1 plus cisplatin followed by gastrectomy with D2 plus PAND
were performed. Patients with bulky nodal disease with or without lymphadenopathy restricted to the station
No. 16a2-b1 region were eligible. Peritoneal metastasis was ruled out and the CY1 status was determined by
staging laparoscopy prior to registration. The trial showed favorable results: a curative resection rate of
82% and 3- and 5-year overall survival (OS) rates of 59% and 53%, respectively . Therefore, this treatment
[6]
strategy could be recommended for institutions with sufficient expertise in PAND.

Another phase II trial exploring multimodal treatment for patients with para-aortic lymph node metastases
limited to stations No. 16a2-b1 was performed in China. This study employed a combination of capecitabine
and oxaliplatin (XELOX) as induction chemotherapy. In total, 48 patients were enrolled. After a median of
4 cycles of chemotherapy, 28 of the 48 patients (58.3%) underwent conversion surgery. The median OS of