Oligometastatic Gastric Cancer: Novel Considerations for Personalized Approach.

Oligometastatic disease (OMD) is currently known as an intermediate state of cancer, characterized by a limited number of systemic metastatic lesions for which local ablative therapy could be curative. Indeed, data from multiple clinical trials have illustrated an increase in overall survival (OS) for cancer patients when local ablative therapy was included in the systemic adjuvant therapy. Given that no driver and somatic mutations specific to OMD are currently established, the diagnosis of OMD is mainly based on the results of X-ray studies. In 2020, 20 international experts from the European Society for Radiotherapy and Oncology (ESTRO) and the European Organization for Research and Treatment of Cancer (EORTC) developed a comprehensive system for the characterization and classification of OMD. They identified 17 OMD characteristics that needed to be assessed in all patients who underwent radical local treatment. These characteristics reflect the tumor biology and clinical features of the disease underlying the development of OMD independently of the primary tumor type and the number of metastatic lesions. In particular, the system involves the characteristics of the primary tumor (e.g., localization, histology, TNM stage, mutational status, specific tumor markers), clinical parameters (e.g., disease-free interval, treatment-free interval), therapies (e.g., local, radical or palliative treatment, the numbers of the therapeutic regimens), and type of OMD (e.g., invasive). Based on the aforementioned criteria, an algorithm was introduced into the clinic to classify OMDs collectively according to their nomenclature. A history of polymetastatic disease (PMD) prior to OMD is used as a criterion to delineate between induced OMD (previous history of PMD after successful therapy) and genuine OMD (no history of PMD). Genuine OMD is divided into two states: recurrent OMD (i.e., after a previous history of OMD) and de novo OMD (i.e., a first newly diagnosed oligometastatic disease). de novo OMD is differentiated into synchronous and metachronous forms depending on the length of time from the primary diagnosis to the first evidence of OMD. In the case of synchronous OMD, this period is less than 6 months. Lastly, metachronous and induced OMD are divided into oligorecurrence, oligoprogression, and oligopersistence, depending on whether OMD is firstly diagnosed during an absence (oligo recurrence) or presence (oligoprogression or oligopersistence) of active systemic therapy. This classification and nomenclature of OMD are evaluated prospectively in the OligoCare study. In this article, we present a practical review of the current concept of OMD and discuss the available prospective clinical trials and potential future directions.

Characterisation and classification of oligometastatic disease: a European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer consensus recommendation

12 Background: According to the ESMO guidelines a metastatic spread involving up to 2 or occasionally 3 sites with 5 or sometimes more metastases (mts) is defined as oligometastatic disease (OMD) and the possibility to offer locoregional treatments (LRTs) should be carefully considered. Tumor load and treatment’s objective (cytoreduction vs disease control) are included among factors affecting the choice of the intensity of the upfront chemotherapy (CT). Nevertheless, no data from clinical trials adopting this definition are currently available, so that the prognostic effect of tumor load, the impact of LRTs and the magnitude of benefit from the CT-intensification in OMD remain unclear. Here we assess the effect of FOLFOXIRI/bev compared to doublets (FOLFOX or FOLFIRI)/bev and the impact of LRTs according to tumor load (OMD vs non-OMD) in a pooled analysis of two randomized phase III studies (TRIBE and TRIBE2). Methods: Subgroup analyses for ORR, PFS and OS were performed according to tumor load at baseline. OMD was defined as up to 5 mts, up to 3 mts in one organ, up to 3 affected organs, mts size ≤ 3 cm, absence of ascites and peritoneal, bone and central nervous system mts. Results: Among 1187 patients (pts) enrolled, 1158 were classifiable: 126 as OMD (11%) and 1032 as non-OMD (89%). Pts with OMD had longer PFS (14.3 vs 10.5 months (mos); p < 0.01) and OS (44.3 vs 24.0 mos; p < 0.01) compared with those with non-OMD. These results were confirmed in multivariable models (p < 0.01). Also among pts who underwent LRTs with curative intent during first line (N = 202), those with OMD at baseline (N = 35) reported longer OS than those with non-OMD (59.6 vs 50.6 mos; p = 0.04). The benefit provided by FOLFOXIRI/bev compared to doublets/bev was confirmed in the OMD subgroup with no interaction effect between treatment arm and tumor load in terms of ORR, PFS and OS (p for interaction = 0.10, 0.58 and 0.23, respectively). Conclusions: OMD is confirmed as a positive prognostic factor and is associated with a higher magnitude of long-term benefit from LRTs than non-OMD. The positive impact of the intensification of the upfront CT is independent of tumor load.

Background: In the present study we review and discuss the current evidence and suggest how to proceed in the management of oligometastatic disease in upper gastrointestinal cancer. Methods: An electronic search of the PubMed database for relevant articles was performed. Results: Both the search for ‘oligometastasis', ‘oligometastases', ‘oligometastatic', ‘oligometastatic disease' as well as ‘esophageal' and ‘esophageal cancer' and the search for ‘oligometastasis', ‘oligometastases', ‘oligometastatic', ‘oligometastatic disease' as well as ‘gastric', ‘gastric cancer', ‘stomach', and ‘stomach cancer' yielded very few studies. Most data need to be extrapolated in general studies on oligometastatic diseases of different origins. No randomized controlled trial could be found. Conclusion: In the absence of data to formulate recommendations on how to proceed in the treatment of oligometastatic disease in upper gastrointestinal cancer, a more aggressive treatment of oligometastatic disease can be considered in patients whose tumors show a more favorable neoplastic behavior after the ‘test of time'. The RENAISSANCE study will certainly deliver important data regarding this aspect.

ABSTRACTMetastatic gastric cancer traditionally hinders surgical treatment options, confining them to palliative procedures. The presence of metastases in these tumors is classified as M1, irrespective of their characteristics, quantity, or location. However, oligometastatic disease emerged as an intermediate state between localized and widely disseminated cancer. It exhibits diverse patterns based on metastatic disease extent, type, and location. Adequately addressing this distinctive metastatic state necessitates tailored strategies that surpass the realm of palliative care. Differentprimary tumor types present discernible scenarios of oligometastatic disease, including preferred sites of occurrence and chronological progression. Due to the novelty of this theme and the heterogeneity of the disease, uncertainties still exist, and the ability to provide confident guidelines is challenging. Currently, there are no effective predictors to determine the response and provide clear indications for surgical interventions and systemic treatments in oligometastatic disease. Treatment decisions are commonly based on apparent disease control by systemic therapies, with a short observation period and imaging assessments. Nonetheless, the inherent risk of misinterpretation remains a constant concern. The emergence of novel technologies and therapeutic modalities, such as immunotherapy, cellular therapy, and adoptive therapies, holds the potential to reshape the landscape of surgical treatment for the oligometastatic disease in gastric cancer, expanding the surgeon’s role in this multidisciplinary approach. Prospective tools for patient selection in oligometastatic gastric cancer are being explored. Using non-invasive, cost-effective, widely available imaging techniques that provide real-time information may revolutionize medical practice, ensuring precision medicine accessibility, even in resource-constrained small healthcare facilities. Incorporating molecular classifications, liquid biopsies, and radiomic analysis in a complementary protocol will augment patient selection precision for surgical intervention in oligometastasis. Hopefully, these advancements will render surgeries unnecessary in many cases by providing highly effective alternative treatments.

To investigate the current status of diagnosis and treatment of early gastric cancer in China, based on the nationwide survey by China Gastrointestinal Cancer Surgery Union. The union sent questionnaires on basic diagnosis and treatment data of gastric and colorectal cancer to all the centers of the union. Different centers collected and summarized their data by year and sent back the questionnaires to the e-mail of theunion(gi_union@foxmail.com) for summary. From 2014 to 2016, the union collected 285 questionnaires from 85 centers all over China. In these 3 years, a total of 88 340 cases of gastric cancer were summarized and there were 17 187 cases of early gastric cancer (part of the data was not available in some centers). The proportion of early gastric cancer varied from 19.5%(5711/29290) in 2014 to 19.0%(6081/32050) in 2015 and 20.0%(5395/27000) in 2016. Significant difference was found among them (χ2=9.553, P=0.008). Significant differences existed not only in the proportion of early gastric cancer between the south (20.9%, 7618/ 36518) and the north (18.5%, 9569/51822) of China (χ2=78.468, P=0.000), but also between the general (20.4%, 11991/58672) and the specialized (17.5%, 5196/29668) hospitals(χ2=107.473, P=0.000). Ultrasonic endoscope was used as routine practice in 10(17.5%, 10/57) general hospitals and 9(56.2%,9/16) specialized hospitals, and significant difference was found between them (χ2=9.721, P=0.002). A total of 4555 early gastric cancer patients received endoscopic therapy. The proportion of patients receiving endoscopic therapy was significantly different between the hospitals in the first-tier cities (36.0%, 2243/6233) and the other cities (21.1%, 2312/10954) (χ2=451.526, P=0.000), and between the hospitals with more than 800 gastric cancer patients per year (28.9%, 3434/11884) and those with less than 800 gastric cancer patients (21.1%, 1121/5303)(χ2=113.270, P=0.000). 37.1%(5270/14186) of early gastric cancer patients received laparoscopic surgery. The proportion of patients receiving laparoscopic surgery was 39.4%(3807/9651) in general hospitals and 32.3%(1463/4535) in specialized hospitals, whose difference was significant (χ2=68.244, P=0.000). The proportion of patients receiving laparoscopic surgery was 29.3%(1269/4328) in the first-tier cities and 40.6%(4001/9858) in the other cities, whose difference was significant as well(χ2=163.480, P=0.000). The proportion of patients receiving laparoscopic surgery was significantly different between the hospitals with more than 800 gastric cancer patients per year(34.5%, 3425/9929) and those with less than 800 gastric cancer patients (43.3%, 1845/4257) (χ2=100.057, P=0.000), and between the hospitals in the south (42.4%, 2552/6016) and those in the north (33.3%, 2718/8170) of China (χ2=124.296, P=0.000). 48.5%(6975) of early gastric cancer patients staged pT1a and 51.5%(7402) staged pT1b. Lymph node metastasis was found in 12.7%(1825/14377) of early gastric cancer. The lymph node metastasis rate of pT1a and pT1b was 5.7%(399/6975) and 19.3%(1426/7402), respectively. The lymph node metastasis rate of early gastric cancer varied from 12.7%(510/4017) in 2014 to 12.2%(668/5494) in 2015 and 13.3%(647/4866) in 2016. The data report of China Gastrointestinal Cancer Surgery Union partly reflects the epidemiologic characteristics, current status of diagnosis and treatment of early gastric in China.

Background Five to eight percent of breast cancer (BC) patients present with distant metastasis at diagnosis, known as ‘de Novo’ metastatic breast cancer (dnMBC). Recent data showed that approximately 40% of dnMBC patients undergo locoregional treatment (LRT). LRT treatment modalities for metastasis and primary tumor benefit a subset of patients with oligometastatic disease. Our study group has recently demonstrated two prospective studies regarding this topic with favorable outcomes. MF07-01 IMET study, one of the first clinical randomized trials, showed that the patients with the diagnosis of dnMBC undergoing LRT followed by systemic therapy had an additional 14% OS benefit by the end of the 10-year follow-up when compared with others who received only systemic therapy. A prospective multicenter registry study MF14-01 BOMET also presented LRT prolonged survival and decreased locoregional recurrence in a prospective registry study with a median follow-up of 3 years. Timing of primary breast surgery either at diagnosis or after systemic treatment provided a survival benefit similar to systemic therapy alone in bone-only dnMBC patients. Although, the optimal timing of concurrent endocrine therapy, radiotherapy, and/or sequential surgery remains unclear. Hypothesis We hypothesize that in the era of modern radiotherapy and endocrine therapy, concurrent radiation and endocrine therapy will be non-inferior to sequential treatment modalities in terms of locoregional and systemic disease control in dnMBC. ER/PR (+), Her2 neu (-) oligometastatic dnMBC patients are potentially curable with multimodality treatments. Objectives The primary objective is to perform a Phase I study to evaluate the feasibility of this curative intent treatment approach for patients with oligometastatic disease. Secondary objectives are to present the treatment response evaluating with CTC and/or ctDNA, and IHC and marker changes with multimodality treatments Methods Postmenopausal ER/PR (+) and Her2 neu (-), oligometastatic dnMBC patients will be enrolled in the study. Inclusion criteria: Primary breast tumor amenable for complete surgical resection, patients in good physical condition for receiving protocol-driven locoregional and systemic treatments and radiotherapy; Bone-only oligometastatic disease (5 or less metastasis); Primary tumor biopsy, metastatic site biopsy (ER/PR, Her2, Ki67). Exclusion criteria: Primary tumor not amenable for complete resection; primary tumor with extended infection, bleeding, or necrosis; patients with poor physical condition which prevents the patient from receiving protocol-driven locoregional and systemic treatment; synchronous primary cancer at the contralateral breast; clinically involved contralateral axillary nodes; patients not suitable for adequate follow-up, and failure to give informed consent. Study Design: • RT to the primary tumor (Hypo fractionated) + AI concurrent, Collect CTC and/or ctDNA • Add CDK4/6i to AI 2-4 weeks after RT + (6 months) • RT to bone metastasis (if still visible), Collect CTC and/or ctDNA + (12 months) • Primary Breast Surgery, Collect CTC and/orctDNA, ER/PR/Her 2 in the final specimen + • CDK4/6i +AI until progression and/or unmanageable toxicity Conclusion We hypothesize that in the era of modern radiotherapy and endocrine therapy, concurrent radiation and endocrine therapy will be non-inferior to sequential treatment modalities in terms of locoregional and systemic disease control in dnMBC. ER/PR (+), Her2 neu (-) oligometastatic dnMBC patients are potentially curable with multimodality treatments. Citation Format: Atilla Soran, Serdar Ozbas, Lutfi Dogan, Kamuran İbis, Mutlu Dogan, M Selam, Kazim Senol, Secil Ak Aksoy, Mine Ozsen, Sibel Cetintas, Turkkan Evrensel, Efe Sezgin. Preoperative radiotherapy and systemic therapy following surgery in ‘de novo’ metastatic breast cancer (Protocol MF22-01; Intervention Systemic Treatment METastasis-ISTMET) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-21-01.

GR01.05 Site of Oligometastases

Gastric cancer is the second most common malignancy and the one of the leading causes of cancer-related death in China. In particular, the survival rate of patients with stage IV or unresectable gastric cancer is very poor. Conversion therapy for stage IV gastric cancer has been the main subject with much attention recently. It is defined to achieve an R0 surgical resection after chemotherapy for originally unresectable cancer due to technical and/or oncological reasons. However, the optimal indications for conversion surgery are still controversial, and how to select the most appropriate candidates for conversion therapy remains to be clarified. A new biological category for stage IV gastric cancer proposed by K Yoshida from Gifu University has been tested out in some trials, from which stage IV gastric cancer can be divided into two different classifications based on the absence (category 1: potentially resectable metastasis and category 2: marginally resectable metastasis) or presence (category 3:incurable and unresectable metastasis and category 4: non-curable metastasis) of macroscopic peritoneal dissemination. The optimal indications for conversion therapy mainly include the patients with category 2, and partially for patients with categories 3 and 4. A surgery-oriented classification proposed by Peking University Cancer Hospital tried to classify the stage IV gastric cancer for conversion therapy. It would be classified as resectable and unresectable categories, depending on uhether R0 resection is available by preoperative evaluation. In this classification, unresectable cancer can be further classified as conversed, partly conversed and non-conversed types based on extent of cancer metastasis. The resection of primary and metastatic lesion in unscreened stage IV gastric cancer was not testified to improve survival. REGATTA trial has identified no significant difference in survival rate between the chemotherapy only and palliative gastrectomy with postoperative chemotherapy for stage IV gastric cancer with a single non-curable factor. With development of conversion therapy, a consensus has been reached that the patients with unresectable gastric cancer initially exhibiting one non-curative factor, if having clinical response to chemotherapy, may obtain a survival benefit from subsequent R0 radical gastrectomy. Several novel combined chemotherapy regimens occasionally allow for conversion of an initially unresectable gastric cancer to resectable cancer in clinical practice. Conversion surgery may result in long-term survival in selected patients who respond to chemotherapy. Several previous studies have evaluated the positive prognostic role of surgery after chemotherapy in stage IV gastric cancer patients with one non-curative factor, such as peritoneal metastasis, para-aortic lymph node metastasis or liver metastasis. Gastric cancer is a highly heterogeneous tumor in nature, consisting of varying aggressive biological characteristics. Oncologically stage IV gastric cancer is a systemic disease, and the complete response to any therapy is really very rare, so that conversion therapy is a great clinical challenging problem for gastric cancer patients. Due to the multi-pathway metastasis, perioperative systemic chemotherapy is the most important in conversion therapy for stage IV gastric cancer, and a radical surgical resection is the key to improve prognosis. A good local control does not necessarily lead to prolonged survival in patients with stage IV gastric cancer, in which other sites metastases often emerge even after successful local-regional cancer-oriented treatment. To date, most reports of conversion therapy for gastric cancer were from single-center or retrospective study. If more reliable evidences are to be obtained, more multi-center and prospective RCT studies must be carried out.

Locoregional treatment of esophageal oligometastatic disease to the liver: single center experience, a systematic review and meta-analysis.

Radiotherapy, along with other loco-regional interventions, is conventionally utilized as a palliative approach to alleviate symptoms and mitigate oncological emergencies in advanced non-small cell lung cancer (NSCLC). Thanks to the ongoing improvement of medical treatments in the last decade, such as targeted therapy and immunotherapy, the survival of patients with advanced NSCLC has been considerably prolonged, making it feasible and clinically beneficial for radiotherapy to play a more active role in highly selected subpopulations. In this review, we will focus on the evolving roles of radiotherapy in advanced NSCLC. First of all, among patients who are initially unable to tolerate aggressive treatment due to severe symptoms caused by metastases and/or tumor emergencies, timely radiotherapy could significantly improve their performance status (PS) and general condition, thus giving them a chance for intensive treatment and prolonged survival. The efficacy, potential candidates, and optimal dose-fractionation regimens of radiotherapy in this clinical scenario will be discussed. Additionally, radiotherapy can play a curative role as a concurrent therapy, consolidation therapy, and salvage therapy for patients with oligo-metastatic, oligo-residual, and oligo-progressive disease, respectively. Accumulating evidence from recent clinical trials, basic research, and translational investigations regarding the potentially curative roles of radiotherapy in NSCLC patients with oligo-metastatic disease will be summarized. Moreover, with the advent of various small molecular tyrosine kinase inhibitors (TKIs), the treatment efficacy and overall survival of oncogene-addicted NSCLC with brain metastases have been significantly improved, and the clinical value and optimal timing of cranial radiotherapy have become topics of much debate. Finally, synergistic antitumor interactions between radiotherapy and immunotherapy have been repeatedly demonstrated. Thus, the immune sensitizing role of radiotherapy in advanced NSCLC is also highlighted in this review.

Despite novel drugs, the prognosis for patients with metastatic gastric cancer remains poor. In rare instances, locoregional therapies are used in addition to standard chemotherapy in patients with oligometastatic involvement. This type of approach has not been supported by solid published evidence. The aim of the present retrospective study was to assess the prognostic impact of factors such as metastatic site, tumour histology and locoregional treatment in patients with metastatic gastric cancer. A total of 184 patients with metastatic gastric or gastroesophageal junction adenocarcinoma who received at least one line of palliative therapy with doublet or triplet chemotherapy were enrolled in the current analysis. Median overall survival (OS) was 8.32 months (95% CI, 7.02–9.41) and median progression-free survival (PFS) was 4.16 months (95% CI, 3.24–5.08). Lung metastases vs. other sites of metastatic involvement [hazard ratio (HR), 0.27; P=0.0133] and intestinal histology (HR, 0.48; P=0.08) were significantly associated with an improved OS. Improved PFS was also observed (HR, 0.49; P=0.10 and HR, 0.72; P=0.08 for lung metastases and intestinal histology, respectively). Second line chemotherapy and locoregional treatment of metastases (surgery or radiotherapy) were associated with improved OS (HR, 0.52; P<0.0001 and HR, 0.35; P<0.0001, respectively). Multivariate analysis confirmed an independent prognostic role for OS only for locoregional treatment, second line treatment and intestinal histology. The present results suggested that the presence of lung metastases alone was not a relevant prognostic factor and was influenced by the availability of further lines of treatment or by locoregional treatments. Locoregional treatments in patients with oligometastatic disease should be offered as they allow prolonged survival in patients with otherwise relatively short life expectancy.

Oligometastatic disease is recognized as an intermediate state between localised and systemically metastasised disease. The diagnosis, treatment and prognosis of oligometastatic disease is currently based mainly on imaging examination. Previous clinical studies indicated that standard systemic therapy followed by radical local therapy was beneficial for survival in tumor patients with oligometastatic disease. However, different clinical outcomes (such as oligopersistant and oligoprogression) were found in synchronous and/or metachronous oligometastatic disease after the same systemic therapy. This report explored potential factors of different outcomes in tumor patients with oligometastatic disease after neoadjuvant immuno-chemotherapy. A lymphoepithelioma-like carcinoma (LELC) case with stage IIIa was synchronous oligometastatic disease, which was treated with neoadjuvant immuno-chemotherapy (four courses of Albumin-Bound Paclitaxel (300 mg), Carboplatin (400 mg) and Durvalumab (500 mg)) and subsequent surgery. Lymph nodes 1R and 4R were considered as oligoprogression and oligopersistant, respectively. Whole exome sequencing results showed that single nucleotide variation (SNV), copy number variation (CNV), tumor mutational burden (TMB), microsatellite instability (MSI), human resource development (HRD) and mutant-allele tumor heterogeneity (MATH) were similar between 1R and 4R samples. Tumor-infiltrating immune cells using a multiplex immunoflourescence histochemistry (mIHC) test revealed that immune checkpoints PD1, PD-L1 and CD39 were high expression and there was a low level of CD8+ T cell in the 4R sample. But levels of CD39+CD8+ and PD-L1+CD8+ T cells were higher in the 1R sample than the 4R sample, suggesting a suppressive tumor immune microenvironment in the 1R oligoprogression lymph node. To demonstrate the result, oligometastatic samples from eight non-small-cell lung cancer (NSCLC) cases with neoadjuvant immuno-chemotherapy and surgery were examined using the mIHC. The results indicated that CD39+CD3+/PD-L1+CD3+/TIM3+CD3+ T cells and/or CD39+CD68+ macrophages in the oligometastatic samples with oligoprogression were high levels. Thus, suppression of tumor-infiltrating immune cells might result in one major factor of different outcomes in oligometastatic disease after neoadjuvant immuno-chemotherapy. Funding Sources: This work was supported by the Wu Jieping Medical Foundation (320.6750.2024-16-16). Citation Format: Peikun Ding, Xiaoxiang Huang, Quanzhou Peng, Kangqi Ren, Longlong Gong, Bin Wang, Lin Yang. Immune suppression of the lymph node microenvironment causes oligoprogression of metastatic cancer after neoadjuvant immuno-chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1597.

Presence of liver metastatic disease in pancreatic ductal adenocarcinoma (PDAC), either synchronous or metachronous after pancreatic resection, is a terminal diagnosis that warrants management with palliative intent as per all international practice guidelines. However, there is an increasing interest on any potential value of surgical treatment of isolated oligometastatic disease in selected cases. To present the published evidence on surgical management of PDAC liver metastases, synchronous and metachronous, and compare the outcomes of these treatments to the current standard of care. A systematic review was performed in line with the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines to compare the outcomes of both synchronous and metachronous liver metastases resection to standard care. 356 studies were identified, 31 studies underwent full-text review and of these 10 were suitable for inclusion. When synchronous resection of liver metastases was compared to standard care, most studies did not demonstrate a survival benefit with the exception of one study that utilised neoadjuvant treatment. However, resection of metachronous disease appeared to confer a survival advantage when compared to treatment with chemotherapy alone. A survival benefit may exist in resection of selected cases of metachronous liver oligometastatic PDAC disease, after disease biology has been tested with time and systemic treatment. Any survival benefit is less clear in synchronous cases; however an approach with neoadjuvant treatment and consideration of resection in some selected cases may confer some benefit. Future studies should focus on pathways for selection of cases that may benefit from an aggressive approach.

In China, peritoneal metastasis of gastric cancer has main characteristics of high incidence, late staging and poor prognosis. However, the proposal of conversion therapy has brought hope to patients. Conversion therapy of peritoneal metastasis in gastric cancer is a novel concept, which aims at down-staging of the gastric cancer′s primary lesion and effectively controlling the peritoneal metastases at the same time through valid chemotherapy and other means. Then the surgeons strive for performing radical gastrectomy and lymph node dissection (D2) to prolong survival time of the patients with advanced gastric cancer and improve their life quality. Systemic chemotherapy is the core of the methods of conversion therapy, while the local intraperitoneal chemotherapy can be used as a supplement. Neoadjuvant intraperitoneal-systemic chemotherapy (NIPS) is the most promising technique as conversion therapy due to the comprehensive advantages of the systemic chemotherapy and local intraperitoneal chemotherapy. In recent years, there were many clinical studies reporting NIPS for conversion therapy of peritoneal metastasis in gastric cancer. Therefore, this paper systematically reviews experiences of clinical application in order to provide references for clinical practice of conversion therapy in gastric cancer. Key words: Gastric neoplasms; Gastric cancer; Peri-toneal metastasis; Conversion therapy; Neoadjuvant intraperitoneal-systemic chemotherapy; Systemic chemotherapy; Hyperthermic intraperitoneal chemotherapy