Phase I/II study of a combination of capecitabine, cisplatin, and intraperitoneal docetaxel (XP ID) in advanced gastric cancer patients with peritoneal metastasis

Outcomes of intraperitoneal chemotherapy for the treatment of gastric cancer with peritoneal metastasis: A comprehensive systematic review and meta-analysis

BACKGROUND

Peritoneal metastasis is common in gastric cancer and linked to poor survival. Treatment of peritoneal metastasis with intraperitoneal chemotherapy has become an accepted practice in some centres. This systematic review and meta-analysis intends to provide a comprehensive evaluation of published evidence for the use of intraperitoneal chemotherapy is gastric cancer patients with peritoneal metastasis.

METHODS

A systematic literature search for studies reporting the use of intraperitoneal chemotherapy for the treatment gastric cancer with macroscopic peritoneal metastasis was performed up until June 2024. Studies were not eligible for inclusion if they described the use of intraperitoneal chemotherapy solely as an adjunct to gastrectomy or cytoreductive surgery. Pooled- and meta-analysis was used to summarise study outcomes.

RESULTS

Fifty-three studies reporting the outcomes of 2446 gastric cancer patients who received intraperitoneal chemotherapy for the treatment of peritoneal metastasis, were included. Three principal methods of intraperitoneal chemotherapy administration were described: catheter based (normothermic) intraperitoneal chemotherapy (n = 28); pressurised intraperitoneal aerosolised chemotherapy (n = 14), and; hyperthermic intraperitoneal chemotherapy (n = 11). The proportion of patients with complete peritoneal disease regression after receiving intraperitoneal chemotherapy was 27 % (95%CI, 14-41). Median overall survival determined was 16.4 months (95%CI, 14.4-18.4). Meta-analysis of data from eight studies comparing combined intraperitoneal and systemic chemotherapy with systemic chemotherapy alone identified a survival benefit for patients receiving intraperitoneal chemotherapy (Hazard ratio 0.57 [95%CI, 0.48-0.67],P < 0.001).

CONCLUSION

Despite variation in published treatment approaches and a lack of evidence from well-designed clinical trials, intraperitoneal chemotherapy may be considered safe and in selected circumstances efficacious.

Lidocaine Enhanced Antitumor Efficacy and Relieved Chemotherapy-Induced Hyperalgesia in Mice with Metastatic Gastric Cancer

With the widespread use of lidocaine for pain control in cancer therapy, its antitumor activity has attracted considerable attention in recent years. This paper provides a simple strategy of combining lidocaine with chemotherapy drugs for cancer therapy, aiming to relieve chemotherapy-induced pain and achieve stronger antitumor efficacy. However, there is still a lack of substantial pre-clinical evidence for the efficacy and related mechanisms of such combinations, obstructing their potential clinical application. In this study, we propose intraperitoneal chemotherapy (IPC) against gastric cancer (GC) as an ideal scenario to evaluate the efficacy of a lidocaine/paclitaxel combination. Firstly, we used human GC cells MKN-45-luc to investigate the antitumor activity and related mechanisms of the lidocaine/paclitaxel combination in vitro. Then, we used C57BL/6 mice with intraperitoneal drug suffusion to evaluate the efficacy of lidocaine to suppress paclitaxel-induced hyperalgesia and related mechanisms. Lastly, in BALB/c tumor-bearing nude mice we evaluated the synergistic antitumor activity and pain-relieving effect of the lidocaine/paclitaxel combination. Our results showed enhanced antitumor activity for the lidocaine/paclitaxel combination, which induced apoptosis, inhibited migration, and the invasion of GC cells in a synergistic manner. In animal models, the lidocaine/paclitaxel combination effectively inhibited growth and peritoneal metastasis of the tumor, resulting in prolonged survival time. Meanwhile, lidocaine showed considerable anti-inflammatory activity alongside its anesthetic effect, which, in combination, effectively relieved hyperalgesia induced by paclitaxel. These results suggested that intraperitoneal suffusion with lidocaine/paclitaxel could be a pain-free IPC formulation with enhanced antitumor activity, which could provide a promising treatment for GC with peritoneal metastasis.

Clinical implications of CT-detected ascites in gastric cancer: association with peritoneal metastasis and systemic inflammatory response

OBJECTIVES

This study aimed to evaluate the diagnostic significance of computed tomography (CT) detected ascites in gastric cancer (GC) with peritoneal metastasis (PM) and investigate its association with systemic inflammatory response.

METHODS

This retrospective study included 111 GCs with ascites (PM: n = 51; No PM: n = 60). Systemic inflammatory indexes, tumor markers, and the CT-assessed characteristics of ascites were collected. The differences in parameters between the two groups were analyzed. Diagnostic performance was obtained by receiver operating characteristic curve analysis. The association between the volume of ascites and clinical characteristics was evaluated with correlation analysis.

RESULTS

In this study, over half of GCs with ascites were not involved with PM. The systemic immune-inflammation index (SII), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), five tumor markers, and the characteristics of ascites showed significant differences between the two groups (all p < 0.05). Among them, SII, NLR, PLR, and the volume of ascites achieved the areas under the curve of 0.700, 0.698, 0.704, and 0.903, respectively. Moreover, the volumes of ascites showed positive correlations with SII, NLR, and PLR in GCs with PM, and the volumes of ascites detected in the upper abdomen were more strongly correlated with CA125 level (all p < 0.05).

CONCLUSION

Many GCs with CT-detected ascites did not occur with synchronous PM. The presence of upper abdominal ascites had certain clinical significance for diagnosing PM in GCs. Systemic inflammatory indexes were elevated and positively correlated with the volume of ascites in GCs with PM, which might suggest the enhanced systemic inflammatory response.

CRITICAL RELEVANCE STATEMENT

CT-detected ascites in the upper abdomen played an indicative role in identifying synchronous PM in GCs, and the systemic inflammatory response was enhanced in GCs with PM, which might be helpful for clinical evaluation.

KEY POINTS

Many GCs with CT-detected ascites did not occur with synchronous PM. CT-detected ascites in the upper abdomen help in identifying PM in GCs. GCs with PM showed elevated systemic inflammatory indexes and enhanced systemic inflammatory response.

Gastric Cancer (GC) with Peritoneal Metastases (PMs): An Overview of Italian PSM Oncoteam Evidence and Study Purposes

Gastric cancer (GC) continues to be one of the leading types of malignancies worldwide, despite an ongoing decrease in incidence. It is the fifth most frequent type of cancer in the world and the fourth leading cause of cancer death. Peritoneal metastases (PMs) occur in 20-30% of cases during the natural history of the disease. Systemic chemotherapy (SC) is undoubtedly the standard of care for patients with GC and PMs. However, with the development of highly effective regimens (SC combined with intraperitoneal chemotherapy), significant tumor shrinkage has been observed in many patients with synchronous GC and PMs, allowing some to undergo curative resection "conversion surgery" with long-term survival. In recent years, there has been growing interest in intraperitoneal chemotherapy for PMs, because the reduced drug clearance associated with the peritoneal/plasma barrier allows for direct and prolonged drug exposure with less systemic toxicity. These procedures, along with other methods used for peritoneal surface malignancies (PSMs), can be used in GCs with PMs as neoadjuvant chemotherapy or adjuvant treatments after radical surgery or as palliative treatments delivered either laparoscopically or-more recently-as pressurized intraperitoneal aerosol chemotherapy. The great heterogeneity of patients with stage IV gastric cancer did not allow us to carry out a systemic review; therefore, we limited ourselves to providing readers with an overview to clarify the indications and outcomes of integrated treatments for GCs with PMs by analyzing reports from the international clinical literature and the specific experiences of our oncoteam.

Study of SOX combined with intraperitoneal high-dose paclitaxel in gastric cancer with synchronous peritoneal metastasis: A phase II single-arm clinical trial

BACKGROUND

Intraperitoneal paclitaxel is proved to be efficient for peritoneal metastasis of gastric cancer. It remains uncertain the efficacy and safety of the triplets regimen which combined intraperitoneal high-dose paclitaxel with systemic SOX in gastric cancer patients with peritoneal metastasis. This study aimed to evaluate the efficacy and safety of intraperitoneal administration of high-dose paclitaxel, intravenous oxaliplatin and S-1 in patients with peritoneal metastatic gastric cancer.

METHODS

This single-center, prospective, single-arm phase II study was conducted between January 2017 and May 2019 in West China Hospital, Sichuan University. Patients diagnosed with primary gastric cancer by histopathology and confirmed synchronous peritoneal metastasis were enrolled. This study aimed to evaluate efficacy and safety of intraperitoneal administration of high-dose paclitaxel (80 mg/m² , d1), intravenous oxaliplatin (100 mg/m² , d1), and S-1 (80 mg/m² , d1-14) of patients. The primary endpoint was 1-year overall survival rate, and the second endpoints were progression-free survival (PFS), overall survival (OS), overall response rate (ORR), disease control rate (DCR) and adverse events.

RESULTS

In this single-arm phase II clinical trial, 49 patients received SOX combined intraperitoneal high-dose paclitaxel treatment. One-year survival rate was 81.6% (95% CI, 68.6-90.0%). Median PFS and OS were 6.50 months (95% CI, 2.89-10.11) and 16.9 months (95% CI, 13.58 to 20.22), respectively; ORR was 55.3% (95% CI, 41.3-68.6) and DCR was 76.6% (95% CI, 62.8-86.4). Thirteen patients underwent second laparoscopic detection, but only nine ultimately underwent radical gastrectomy. Subgroup analysis showed that sPCI ≤12 was a good index for a favorable prognosis. The most frequent grade 3/4 toxicities were neutropenia (40.8%), anemia (22.4%), leukopenia (18.4%), nausea (14.3%), and vomiting (12.2%). None of the patients had any intraperitoneal catheter-related complications.

CONCLUSIONS

Intraperitoneal high-dose paclitaxel with systemic SOX is an effective and tolerable first-line treatment for patients with peritoneal metastatic gastric cancer and patients with sPCI≤12 scores might be recommended crowd for this regimen as conversion therapy.

Intraperitoneal Chemotherapy for Unresectable Peritoneal Surface Malignancies

Malignancies of the peritoneal cavity are associated with a dismal prognosis. Systemic chemotherapy is the gold standard for patients with unresectable peritoneal disease, but its intraperitoneal effect is hampered by the peritoneal-plasma barrier. Intraperitoneal chemotherapy, which is administered repeatedly into the peritoneal cavity through a peritoneal implanted port, could provide a novel treatment modality for this patient population. This review provides a systematic overview of intraperitoneal used drugs, the performed clinical studies so far, and the complications of the peritoneal implemental ports. Several anticancer drugs have been studied for intraperitoneal application, with the taxanes paclitaxel and docetaxel as the most commonly used drug. Repeated intraperitoneal chemotherapy, mostly in combination with systemic chemotherapy, has shown promising results in Phase I and Phase II studies for several tumor types, such as gastric cancer, ovarian cancer, colorectal cancer, and pancreatic cancer. Two Phase III studies for intraperitoneal chemotherapy in gastric cancer have been performed so far, but the results regarding the superiority over standard systemic chemotherapy alone, are contradictory. Pressurized intraperitoneal administration, known as PIPAC, is an alternative way of administering intraperitoneal chemotherapy, and the first prospective studies have shown a tolerable safety profile. Although intraperitoneal chemotherapy might be a standard treatment option for patients with unresectable peritoneal disease, more Phase II and Phase III studies focusing on tolerability profiles, survival rates, and quality of life are warranted in order to establish optimal treatment schedules and to establish a potential role for intraperitoneal chemotherapy in the approach to unresectable peritoneal disease.

Phase 1 trial of intraperitoneal paclitaxel in combination with intravenous cisplatin and oral capecitabine in patients with advanced gastric cancer and peritoneal metastases (IPGP study)

AIMS

Gastric cancer with peritoneal involvement has a poor prognosis. Intraperitoneal (IP) paclitaxel has shown promising results in these patients. However, this approach has only been studied in the Asian population, and in combination with S-1. We investigated the maximum tolerated dose of IP paclitaxel, with a standard chemotherapy combination, in the Australian population.

METHODS

The study of the population included metastatic human epidermal growth factor receptor 2 (HER2) negative gastric adenocarcinoma with peritoneal involvement. Treatment included six 21-day cycles of cisplatin (80 mg/m2 IV, day 1) plus capecitabine (1000 mg/m2 PO BD, days 1-14) plus IP paclitaxel (days 1 and 8). IP paclitaxel doses for cohort 1-3 were 10, 20, and 30 mg/m2 , respectively, in a 3 + 3 standard dose-escalation design.

RESULTS

Fifteen patients were enrolled of which 6 were female and the median age was 63. Two patients developed dose-limiting toxicities. No grade 4/5 toxicities were recorded. The maximum tolerated dose was not reached. Therefore, as defined by the study protocol, the recommended phase-2 dose for IP paclitaxel was determined to be 30 mg/m2 . The 12-month survival rate was 46.7%, and the median survival was 11.5 months (interquartile range [IQR]: 15.3-6.9).

CONCLUSIONS

IP paclitaxel is safe in combination with cisplatin and capecitabine and the recommended phase-2 dose is 30 mg/m2 .

Crosstalk between cancer-associated fibroblasts and immune cells in peritoneal metastasis: inhibition in the migration of M2 macrophages and mast cells by Tranilast

BACKGROUND

The role of tumor-stroma interactions in tumor immune microenvironment (TME) is attracting attention. We have previously reported that cancer-associated fibroblasts (CAFs) contribute to the progression of peritoneal metastasis (PM) in gastric cancer (GC), and M2 macrophages and mast cells also contribute to TME of PM. To elucidate the role of CAFs in TME, we established an immunocompetent mouse PM model with fibrosis, which reflects clinical features of TME. However, the involvement of CAFs in the immunosuppressive microenvironment remains unclear. In this study, we investigated the efficacy of Tranilast at modifying this immune tolerance by suppressing CAFs.

METHODS

The interaction between mouse myofibroblast cell line LmcMF and mouse GC cell line YTN16 on M2 macrophage migration was investigated, and the inhibitory effect of Tranilast was examined in vitro. Using C57BL/6J mouse PM model established using YTN16 with co-inoculation of LmcMF, TME of resected PM treated with or without Tranilast was analyzed by immunohistochemistry.

RESULTS

The addition of YTN16 cell-conditioned medium to LmcMF cells enhanced CXCL12 expression and stimulated M2 macrophage migration, whereas Tranilast inhibited the migration ability of M2 macrophages by suppressing CXCL12 secretion from LmcMF. In PM model, Tranilast inhibited tumor growth and fibrosis, M2 macrophage, and mast cell infiltration and significantly promoted CD8 + lymphocyte infiltration into the tumor, leading to apoptosis of cancer cells by an immune response.

CONCLUSION

Tranilast improved the immunosuppressive microenvironment by inhibiting CAF function in a mouse PM model. Tranilast is thus a promising candidate for the treatment of PM.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Gastric Cancer with Synchronous Peritoneal Metastases: Multicenter Study of 'Italian Peritoneal Surface Malignancies Oncoteam-S.I.C.O.'

BACKGROUND

The development of multimodality treatment, including cytoreductive surgery (CRS) with heated intraperitoneal chemotherapy (HIPEC), has led to promising results in selected patients with peritoneal disease of gastric origin. The aim of this study was to investigate the short- and long-term outcomes of CRS/HIPEC in the treatment of synchronous peritoneal metastasis in gastric cancer.

METHODS

The Italian Peritoneal Surface Malignancies Oncoteam-S.I.C.O. retrospective registry included patients with synchronous peritoneal malignancy from gastric cancer submitted to gastrectomy with CRS and HIPEC between 2005 and 2018 from 11 high-volume, specialized centers.

RESULTS

A total of 91 patients with a median age of 58 years (range 26-75) were enrolled. The median overall survival (OS) time for the whole group of patients was 20.2 months (95% confidence interval [CI] 11.8-28.5] and the median recurrence-free survival (RFS) was 7.3 months (95% CI 4-10.6). The completeness of cytoreduction score (CCS) of 0 and Peritoneal Cancer Index (PCI) score of ≤ 6 groups showed a significantly better long-term survival (median OS 40.7 and 44.3 months, respectively) compared with the incomplete resected groups (median OS 10.7 months, p = 0.003) and PCI score of > 6 group (median OS 13.4 months, p = 0.005). A significant difference was observed in the survival rate according to neoadjuvant treatment (untreated patients: 10.7 months, 95% CI 5.1-16.2; treated patients: 35.3 months, 95% CI 2.8-67.8; p = 0.022).

CONCLUSIONS

In referral centers, CRS and HIPEC after neoadjuvant treatment significantly improved survival in selected patients. Patients with a PCI score ≤ 6, complete cytoreduction, negative nodal involvements, and negative cytology had encouraging results, showing a clinically meaningful survival.

Neoadjuvant Intraperitoneal and Systemic Chemotherapy Versus Neoadjuvant Systemic Chemotherapy With Docetaxel, Oxaliplatin, and S-1 for Gastric Cancer With Peritoneal Metastasis: A Propensity Score Matched Analysis

BACKGROUND

The optimal treatment for gastric cancer with peritoneal metastasis (GCPM) remains debatable. This study aimed to compare the efficacy and safety of neoadjuvant intraperitoneal and systemic chemotherapy (NIPS) versus neoadjuvant systemic chemotherapy (NSC) for GCPM.

METHODS

Patients of GCPM received neoadjuvant chemotherapy with docetaxel, oxaliplatin and S-1 between January 2011 and June 2019 were retrospectively evaluated. Propensity score matched (PSM) analysis was carried out to reduce the selection bias. Multivariate Cox regression model was applied to screen the prognostic factors.

RESULTS

After PSM processing, 71 patients in each group were matched among the 186 GCPM patients included. NIPS yielded a better ascites and cytology response to chemotherapy, higher conversion resection rate and R0 resection rate than NSC. The overall survival (OS) rate in NIPS group was better than that in NSC group. Multivariate analysis revealed that the P stage, ascites response, conversion surgery rate and R0 resection rate were independent prognostic factors. Subgroup analysis indicated that NIPS showed a survival benefit over NSC only in patients with cT3-4a, P1-2, whose cytology turned negative, and who received conversion surgery; while not in patients with cT4b, P0 or P3, whose cytology did not turn negative, or who did not receive conversion surgery.

CONCLUSIONS

NIPS is a safe and feasible treatment for GCPM, which showed more benefit than NSC.

Established fibrous peritoneal metastasis in an immunocompetent mouse model similar to clinical immune microenvironment of gastric cancer

Background

Peritoneal metastasis (PM) in gastric cancer (GC) is characterized by diffusely infiltrating and proliferating cancer cells accompanied by extensive stromal fibrosis in the peritoneal space. The prognosis of GC with PM is still poor regardless of the various current treatments. In order to elucidate the cause of difficulties in PM treatment, we compared the tumor immune microenvironment (TME) in primary and PM lesions in GC. In addition, a PM model with fibrous stroma was constructed using immunocompetent mice to determine whether its TME was similar to that in patients.

Methods

Immuno-histochemical analyses of infiltrating immune cells were performed in paired primary and PM lesions from 28 patients with GC. A C57BL/6 J mouse model with PM was established using the mouse GC cell line YTN16 either with or without co-inoculation of mouse myofibroblast cell line LmcMF with α-SMA expression. The resected PM from each mouse model was analyzed the immunocompetent cells using immunohistochemistry.

Results

The number of CD8⁺ cells was significantly lower in PM lesions than in primary lesions (P < 0.01). Conversely, the number of CD163⁺ cells (M2 macrophages) was significantly higher in PM lesions than in primary lesions (P = 0.016). Azan staining revealed that YTN16 and LmcMF co-inoculated tumors were more fibrous than tumor with YTN16 alone (P < 0.05). Co-inoculated fibrous tumor also showed an invasive growth pattern and higher progression than tumor with YTN16 alone (P = 0.045). Additionally, YTN16 and LmcMF co-inoculated tumors showed lower infiltration of CD8⁺ cells and higher infiltration of M2 macrophages than tumors with YTN16 alone (P < 0.05, P < 0.05). These results indicate that LmcMF plays as cancer-associated fibroblasts (CAFs) by crosstalk with YTN16 and CAFs contribute tumor progression, invasion, fibrosis, and immune suppression.

Conclusions

This model is the first immunocompetent mouse model similar to TME of human clinical PM with fibrosis. By using this model, new treatment strategies for PM, such as anti-CAFs therapies, may be developed.

Clinical outcomes of capecitabine-based versus S-1-based regimens as first-line chemotherapy in patients with unresectable or metastatic gastric cancer: a propensity score matched single-center comparison

Background

Fluoropyrimidine-based regimens are the cornerstone of first-line chemotherapy for metastatic gastric cancer (GC). Capecitabine or S-1 might be used as an alternative to infusional 5-fluorouracil, especially in pan-Asian. This study aimed to compare the clinical outcomes of capecitabine-based and S-1-based regimens as first-line chemotherapy in Chinese patients with unresectable or metastatic GC.

Methods

We conducted a retrospective study including unresectable or metastatic GC patients treated with the capecitabine-based or S-1-based regimen as first-line chemotherapy at the First Hospital of China Medical University. Propensity score matching (PSM) analysis was performed to reduce selection bias. Overall survival (OS) outcomes were compared using the Kaplan-Meier method and log-rank test. Prognostic significance was determined using multivariate Cox regression analysis. In addition, subgroup analyses were conducted to determine the effectiveness of capecitabine-based and S-1-based regimens in clinically relevant patient subsets.

Results

The clinical data of 469 patients included between October 2005 and September 2018. PSM analysis identified 187 patients receiving capecitabine-based or S-1-based regimen. No significant difference in OS (10.7 vs. 11.1 months, P=0.523) was detected between the two groups after PSM. In the subgroup analysis, the median OS (12.2 vs. 9.3 months, P=0.013) was longer for patients with peritoneum metastasis who received the capecitabine-based regimen compared to those who received the S-1-based regimen.

Conclusions

No significant difference in clinical outcomes was observed between the capecitabine and S-1-based regimen as first-line chemotherapy for metastatic or unresectable GC patients in China. The capecitabine-based regimen should be considered in the treatment of the GC patients with peritoneum metastasis.

Multicenter Retrospective Analysis of Intraperitoneal Paclitaxel and Systemic Chemotherapy for Advanced Gastric Cancer with Peritoneal Metastasis

Purpose

The objective of the present retrospective analysis was to describe the experience of intraperitoneal (IP) paclitaxel and systemic chemotherapy in patients with peritoneal metastasis (PM) of advanced gastric cancer (AGC) in a multicenter setting in Korea.

Materials and Methods

The medical records of patients with AGC, who were diagnosed with PM between January 2015 and December 2018, were reviewed. IP catheter was placed in the pouch of Douglas and was used for the administration of IP paclitaxel chemotherapy.

Results

We reviewed the clinical outcomes of IP paclitaxel and systemic chemotherapy administration in 82 patients at six institutions in Korea. Mean number of IP chemotherapy cycles was 6.6. The mean peritoneal cancer index (PCI) was 21.9. Postoperative complications related to IP catheter and port were observed in 15 patients. The overall median survival was 20.0 months. A significant difference was observed in the survival rate according to the ascites grade (grade I and II, 24.1 months; grade III and IV, 15.3 months; P=0.014) and PCI grade (grade I, 25.6 months; grade II and III, 16.3 months; P=0.023).

Conclusions

The feasibility of IP paclitaxel and systemic chemotherapy administration was demonstrated in this experience-based retrospective analysis suggesting that the procedure is beneficial in patients with PM of AGC.

Issues on peritoneal metastasis of gastric cancer: an update

BACKGROUND

Peritoneal metastasis (PM) is one of the most common forms of metastasis with a very poor prognosis in patients with gastric cancer (GC). The mechanisms, diagnosis, and management of PM remain controversial.

MAIN BODY

Stephen Paget's "seed-and-soil" hypothesis gives us an illustration of the mechanisms of PM. Recently, hematogenous metastasis and exosomes from GC are identified as novel mechanisms for PM. Diagnostic accuracy of conventional imaging modalities for PM is not satisfactory, but texture analysis may be a useful adjunct for the prediction of PM. Biological markers in peritoneal washings are helpful in identifying patients at high risk of PM, but many limitations remain to be overcome. Response of PM from systemic chemotherapy alone is very limited. However, conversion therapy is confirmed to be safe and able to prolong the survival of GC patients with PM. As an important part of conversion therapy, intraperitoneal chemotherapy with taxanes has become an ideal approach with several advantages. Additionally, gastrectomy should be considered in patients who would tolerate surgery if a remarkable response to chemotherapy was observed.

CONCLUSION

Texture analysis is a reliable adjunct for the prediction of PM, and conversion therapy provides a new choice for GC patients with PM. The underlying mechanisms and new biological markers for GC patients with PM should be the direction of future studies. Furthermore, significant aspects of conversion therapy, such as timing and method of the operation, and the indications remain to be clarified.

Treatment of patients with peritoneal metastases from gastric cancer

Despite recent advances in chemotherapy, outcomes of patients with peritoneal metastases (PM) from gastric cancer are still very poor and standard treatment has not been established. Although oral S‐1 appears to be effective for patients with PM, the effects of systemic chemotherapy are limited. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) yield fewer benefits in patients with PM from gastric cancer than in patients with PM from other malignancies. In comparison, repeated intraperitoneal chemotherapy (RIPEC) with taxanes using an implantable peritoneal access port has a pharmacokinetic advantage for the control of peritoneal lesions and in combination with systemic chemotherapy can result in surprisingly long‐term survival in patients with PM from gastric cancer. Herein, we review the results of recent clinical studies specifically targeting PM from gastric cancer and discuss future prospects for an intraperitoneal approach to the ideal treatment of patients with gastric cancer with peritoneal involvement.