International consensus on the management of metastatic gastric cancer: step by step in the foggy landscape : Bertinoro Workshop, November 2022.

BACKGROUND: Many gastric cancer patients in Western countries are diagnosed as metastatic with a median overall survival of less than twelve months using standard chemotherapy. Innovative treatments, like targeted therapy or immunotherapy, have recently proved to ameliorate prognosis, but a general agreement on managing oligometastatic disease has yet to be achieved. An international multi-disciplinary workshop was held in Bertinoro, Italy, in November 2022 to verify whether achieving a consensus on at least some topics was possible. METHODS: A two-round Delphi process was carried out, where participants were asked to answer 32 multiple-choice questions about CT, laparoscopic staging and biomarkers, systemic treatment for different localization, role and indication of palliative care. Consensus was established with at least a 67% agreement. RESULTS: The assembly agreed to define oligometastases as a "dynamic" disease which either regresses or remains stable in response to systemic treatment. In addition, the definition of oligometastases was restricted to the following sites: para-aortic nodal stations, liver, lung, and peritoneum, excluding bones. In detail, the following conditions should be considered as oligometastases: involvement of para-aortic stations, in particular 16a2 or 16b1; up to three technically resectable liver metastases; three unilateral or two bilateral lung metastases; peritoneal carcinomatosis with PCI ≤ 6. No consensus was achieved on how to classify positive cytology, which was considered as oligometastatic by 55% of participants only if converted to negative after chemotherapy. CONCLUSION: As assessed at the time of diagnosis, surgical treatment of oligometastases should aim at R0 curativity on the entire disease volume, including both the primary tumor and its metastases. Conversion surgery was defined as surgery on the residual volume of disease, which was initially not resectable for technical and/or oncological reasons but nevertheless responded to first-line treatment.

Bidirectional Approach with PIPAC and Systemic Chemotherapy for Patients with Synchronous Gastric Cancer Peritoneal Metastases (GCPM).

BACKGROUND: This study evaluated the efficacy of pressurized intraperitoneal aerosol chemotherapy (PIPAC) with systemic chemotherapy as a bidirectional approach for gastric cancer (GC) patients with synchronous peritoneal metastases (SPM). METHODS: A retrospective analysis of a prospective PIPAC database was queried for patients who underwent a bidirectional approach between October 2019 and April 2022 at two high-volume GC surgery units in Italy (Verona and Siena). Surgical and oncological outcomes were analyzed. RESULTS: Between October 2019 and April 2022, 74 PIPAC procedures in 42 consecutive patients with Eastern Cooperative Oncology Group performance status ≤2 were performed-32 patients treated in Verona and 10 in Siena. Twenty-seven patients (64%) were female and median age at first PIPAC was 60.5 years (I-III quartiles: 49-68 years). Median Peritoneal Cancer Index (PCI) was 16 (I-III quartiles: 8-26) and 25 patients (59%) had at least two PIPAC procedures. Major complications according to the Common Terminology Criteria for Adverse Events (CTCAE; 3 and 4) occurred in three (4%) procedures, and, according to the Clavien-Dindo classification (>3a), one (1%) severe complication occurred. There were no reoperations or deaths within 30 days. Median overall survival (mOS) from diagnosis was 19.6 months (range 14-24), and mOS from first PIPAC was 10.5 months (range 7-13). Excluding cases with very heavy metastatic peritoneal burden, with PCI from 2 to 26, treated with more than one PIPAC, mOS from diagnosis was 22 months (range 14-39). Eleven patients (26%) underwent curative-intent surgery after a bidirectional approach. R0 was achieved in nine (82%) patients and complete pathological response was obtained in three (27%) cases. CONCLUSIONS: Patient selection is associated with bidirectional approach efficacy and feasibility for SPM GC treatment, which may allow potentially curative surgical radicalization in highly selected cases.

Robotic versus open Ivor-Lewis esophagectomy: A more accurate lymph node dissection without burdening the leak rate.

BACKGROUND: Robotic-assisted minimally invasive esophagectomy (RAMIE) combines the beneficial effects of minimally invasive surgery on postoperative complications, especially on pulmonary ones, with the safety of the anastomosis performed in open surgery. Moreover, RAMIE could allow a more accurate lymphadenectomy. METHODS: We reviewed our database to identify all patients with adenocarcinoma of the esophagus treated by Ivor-Lewis esophagectomy in the period January 2014 to June 2022. Patients were divided according to the thoracic approach into RAMIE and open esophagectomy (OE) groups. We compared the groups for early surgical outcomes, 90-day mortality as well as R0 rate, and the number of lymph nodes harvested. RESULTS: We identified 47 patients in RAMIE and 159 patients in the OE group. Baseline characteristics were comparable. Operative time was significantly longer for RAMIE procedures (p < 0.01); however, we did not observe the difference in overall (RAMIE 55.5% vs. OE 61%, p = 0.76) and severe complications rate (RAMIE 17% vs. OE 22.6%, p = 0.4). The anastomotic leak rate was 2.1% after RAMIE and 6.9% after OE (p = 0.56). We did not report the difference in 90-day mortality (RAMIE 2.1% vs. OE 1.9%, p = 0.65). In the RAMIE group, we observed a significantly higher number of thoracic lymph nodes harvested, with a median of 10 lymph nodes in the RAMIE group versus 8 in the OE group (p < 0.01). CONCLUSIONS: In our experience, RAMIE has morbimortality rates comparable to OE. Moreover, it allows a more accurate thoracic lymphadenectomy which results in a higher thoracic lymph nodes retrieval rate.

Treatment of EGJ Cancer within or outside Clinical Trials: Does the Setting Matter? A Monocentric Prospective Observational Study.

INTRODUCTION: RCTs support neoadjuvant chemoradiotherapy (nCRT) followed by surgery in locally advanced esophago-gastric junction (LA-EGJ) adenocarcinoma. However, RCTs are performed in highly controlled settings with limited representativeness of real-life patients (RLS). The aim of the study was to compare the outcomes in RLS and clinical trial settings. METHODS: The outcomes of RLS, which comprised 125 patients consequently treated for LA-EGJ adenocarcinoma between 2012 and 2017, were compared with the phase II trial (PIIS), performed on 65 patients from 2003 to 2011. RESULTS: About half of RLS (51.2%) were treated with nCRT according to VR protocol, 20.8% with standard CRT according to CROSS/Al-Sarraf, 20% with chemotherapy (CT) alone. pCR was 36.8%, 28.6%, and 9.1% after VR protocol, standard CRT, and CT, respectively (p = 0.082), while 3-year overall survival (OS) was 58.6% (95% CI 43.2-71.1%), 32.8% (14.6-52.4%), and 44.8% (21.3-65.9%), respectively (p = 0.030). With respect to PIIS, RLS had a higher proportion of cN+ (94% vs. 54%; p < 0.001) and a lower proportion of pCR after CT/CRT (23% vs. 39%; p = 0.041). Three-year OS was slightly higher, although not significantly, in PIIS (58.9%, 45.1-70.2%) than RLS (47.9%, 37.4-57.7%) and nearly identical to 3-year OS in RLS treated with VR protocol. CONCLUSION: Real-life patients with EGJ adenocarcinoma have more advanced cancer at baseline, lower pathologic response to neoadjuvant treatment than patients enrolled in clinical trials, but similar survival.

Poorly Cohesive Gastric Cancers Showing the Transcriptomic Hallmarks of Epithelial-Mesenchymal Transition Behave Aggressively.

HYPOTHESIS: Poorly cohesive (PC) gastric cancer (GC) exhibits variable clinical behavior, being extremely aggressive in most cases but more indolent at times. We hypothesized that the integrative genomic and gene expression characterization of a PC GC series could help identifying molecular subtypes with potential clinical implications. MATERIALS AND METHODS: 64 PC GCs were assessed for alterations in 409 genes and 30 cases were subjected to transcriptomic profiling of 20,815 genes. RESULTS: A median of 8.2 mutations per Mb (interquartile range 6.9-10.4) was found and a tumor mutational load >10 muts/Mb was significantly associated with patients' worse survival ( P =0.0024). The most frequent mutated genes were CDH1 and TP53 (each 32.8%) followed by PIK3CA (10.9%). In 15 samples (23.4%), at least 1 chromatin remodeling gene was mutated: KMT2D (5 cases); ARID1A and BAP1 (4 cases each); EZH2 , KMT2A , PBRM1 (1 case each). Eight samples (12.5%) had fusion genes involving CLDN18 gene. Gene expression profiling identified 4 different clusters: cluster A associated with epithelial to mesenchymal transition (EMT) signature; cluster B associated to proliferative signature and EMT; cluster C correlated to hedgehog signaling; cluster D showing no enrichment for any of the previous signatures. Notably, cluster A and B showed a worse prognosis compared with clusters C and D ( P =0.0095). CONCLUSION: integrated genomic and transcriptomic analysis suggest the existence of 4 molecular subtypes of PC GC with prognostic significance where EMT features are associated with a worse outcome.

Pretreatment Primary Tumor Stage is a Risk Factor for Recurrence in Patients with Esophageal Squamous Cell Carcinoma Who Achieve Pathological Complete Response After Neoadjuvant Chemoradiotherapy.

BACKGROUND: Although pathological complete response (pCR) after multimodal treatment for esophageal cancer is associated to the best prognosis, recurrence may occur in 20-40% of cases. The present study investigated the recurrence pattern and predictive factors of recurrence after pCR in patients with esophageal cancer. METHODS: In this study, 427 patients received preoperative treatment for either esophageal squamous cell carcinoma (SCC) or adenocarcinoma at Verona University Hospital between 2000 and 2018. Of these, 145 patients (34%) achieved a pCR. Long-term prognosis, recurrence pattern, and risk factors for relapse in pCR patients were analysed. RESULTS: During a median follow-up of 52 months, 37 relapses (25.5%) occurred, mostly at distant level (n = 28). Nearly all locoregional relapses (8/9) were detected in SCC cases. The 5-year overall survival and cancer-related survival were 71.7% (95% confidence interval [CI] 62.6-78.9%) and 77.5% (95% CI 68.5-84.2%) respectively. Male sex, higher body mass index, and cT4 were significant risk factors for recurrence at univariate analysis. The multivariate analysis confirmed the role of cT4 as predictor of recurrence only in SCCs. CONCLUSIONS: Esophageal cancer recurs in about one-fourth of pCR cases. A fair number of local recurrences occurs in SCCs, but the main problem is the systemic disease control. According to our analysis, SCCs patients with cT4 stage have an increased risk to recur, so they should be managed differently by a personalized approach in terms of adjuvant treatment and follow-up.

Personalized therapeutic strategies in HER2-driven gastric cancer.

BACKGROUND: Trastuzumab is the only approved targeted therapy in patients with HER2-amplified metastatic gastric cancer (GC). Regrettably, in clinical practice, only a fraction of them achieves long-term benefit from trastuzumab-based upfront strategy. To advance precision oncology, we investigated the therapeutic efficacy of different HER2-targeted strategies, in HER2 "hyper"-amplified (≥ 8 copies) tumors. METHODS: We undertook a prospective evaluation of HER2 targeting with monoclonal antibodies, tyrosine kinase inhibitors and antibody-drug conjugates, in a selected subgroup of HER2 "hyper"-amplified gastric patient-derived xenografts (PDXs), through the design of ad hoc preclinical trials. RESULTS: Despite the high level of HER2 amplification, trastuzumab elicited a partial response only in 2 out of 8 PDX models. The dual-HER2 blockade with trastuzumab plus either pertuzumab or lapatinib led to complete and durable responses in 5 (62.5%) out of 8 models, including one tumor bearing a concomitant HER2 mutation. In a resistant PDX harboring KRAS amplification, the novel antibody-drug conjugate trastuzumab deruxtecan (but not trastuzumab emtansine) overcame KRAS-mediated resistance. We also identified a HGF-mediated non-cell-autonomous mechanism of secondary resistance to anti-HER2 drugs, responsive to MET co-targeting. CONCLUSION: These preclinical randomized trials clearly indicate that in HER2-driven gastric tumors, a boosted HER2 therapeutic blockade is required for optimal efficacy, leading to complete and durable responses in most of the cases. Our results suggest that a selected subpopulation of HER2-"hyper"-amplified GC patients could strongly benefit from this strategy. Despite the negative results of clinical trials, the dual blockade should be reconsidered for patients with clearly HER2-addicted cancers.

Looking for a strategy in treating peritoneal gastric cancer carcinomatosis: an Italian multicenter Gastric Cancer Research group's analysis.

BACKGROUND: The present study provides a snapshot of Italian patients with peritoneal metastasis from gastric cancer treated by surgery in Italian centers belonging to the Italian Research Group on Gastric Cancer. Prognostic factors affecting survival in such cohort of patients were evaluated with the final aim to identify patients who may benefit from radical intent surgery. METHODS: It is a multicentric retrospective study based on a prospectively collected database including demographics, clinical, surgical, pathological, and follow-up data of patients with gastric cancer and synchronous macroscopic peritoneal metastases. Patients were surgically treated from January 2005 to January 2017. We focused on patients with macroscopic peritoneal carcinomatosis (PC) treated with upfront surgery in order to provide homogeneous evidences. RESULTS: Our results show that patients with peritoneal carcinomatosis cannot be considered all lost. Strictly selected cases (R0/R1 and P1 patients) could benefit from an aggressive surgical approach performing an extended lymphadenectomy and HIPEC treatment. CONCLUSION: The main result of the study is that GC patients with limited peritoneal involvement can have a survival benefit from a surgery with "radical oncological intent", that means extended lymphadenectomy and R0 resection. The retrospective nature of this study is an important bias, and for this reason, we have started a prospective multicentric study including Italian stage IV patients that hopefully will give us more answers.

The amount of signet ring cells is significantly associated with tumour stage and survival in gastric poorly cohesive tumours.

BACKGROUND AND OBJECTIVES: The aim of this study was to evaluate whether the amount of signet ring cells (SRCs) affects clinicopathological characteristics and prognosis of poorly cohesive (PC) gastric tumours. STUDY DESIGN: One hundred seventy-three patients with PC tumours treated at three European centres from 2004 to 2014 were reclassified in three categories: (a) pure SRC cancers (SRC1) (≥90% SRCs); (b) PC carcinoma with SRC component (SRC2) (>10%, <90% SRCs); (c) PC carcinoma not otherwise specified (SRC3) (≤10% SRCs). RESULTS: The percentage of SRCs was inversely related to the pT stage (Spearman's ρ = -0.174, P < .001) and the number of positive nodes coded as a continuous variable (P = .009). Five year cancer-related survival was significantly higher (58%, 95% confidence interval [CI]: 36%-75%) in SRC1 compared with SRC2 (39%, 95% CI: 28%-50%) and SRC3 (38%, 95% CI: 22%-53%), (P = .048). In multivariable analysis, the impact of PC categories on cancer-related survival was significant when controlling for sex, age, pT, pN, and curativity (hazard ratio [HR] of sSRC2 vs SRC1 = 2.08, 95% CI: 1.01-4.29, P = .046; HR of SRC3 vs SRC1 = 2.38, 95% CI: 1.05-5.41, P = .039). CONCLUSION: The percentage of SRCs was inversely related to tumour aggressiveness, with long-term survival significantly higher in SRC1 compared with SRC2 and SRC3 tumours.

Conversion gastrectomy for stage IV unresectable gastric cancer: a GIRCG retrospective cohort study.

BACKGROUND: The aim of this study is to report the experience with conversion surgery from six Gruppo Italiano Ricerca Cancro Gastrico (GIRCG) centers, focusing our analysis on factors affecting survival and the risk of recurrence. METHODS: A retrospective, multicenter cohort study was performed in patients who had undergone conversion gastrectomy between 2005 and 2017. Data were extracted from a GIRCG database including all metastatic gastric cancer patients submitted to surgery. Only stage IV unresectable tumors/metastases which became resectable after chemotherapy were included in this analysis. RESULTS: Forty-five resected M1 patients were included in the analysis. Reasons for being deemed unresectable at diagnosis were peritoneal involvement (PCI > 6) (n = 38, 84.4%), distant metastatic nodes (n = 3, 6.6%) and extensive liver involvement (n = 4, 8.8%). Median follow-up was 25 months (IQR 9-50). Median overall survival from surgery was 15 months and 1-, 3- and 5-year survivals were 57.2, 36.1 and 24%, respectively. Median progression-free survival was 12 months with 1- and 3-year survival of 46.4 and 33.9%, respectively. At cox regression analysis the only independent prognostic factor for OS was the presence of more than one type of metastasis (HR 4.41, 95% CI 1.72-11.3, p = 0.002). A positive microscopic resection margin was the only risk factor for recurrence (HR 5.72, 95% CI 1.04-31.4, p = 0.045). CONCLUSIONS: Unresectable stage IV GC patients could benefit from radical surgery after chemotherapy and achieve long survivals. The main prognostic factor for these patients was the presence of more than one type of extra-gastric metastatic involvement.

Multicenter Study of Presentation, Management, and Postoperative and Long-Term Outcomes of Septegenerians and Octogenerians Undergoing Gastrectomy for Gastric Cancer.

BACKGROUND: The optimal treatment strategy for elderly patients with gastric cancer is still controversial. This study aimed to assess the impact of age on short- and long-term outcomes after treatment for primary gastric cancer. METHODS: From January 2004 to December 2014, a total of 507 patients underwent gastrectomy for gastric adenocarcinoma at two high-volume upper gastrointestinal (GI) centers. The patients were classified into three groups as follows: group A (patients ≤ 69 years old, n = 266), group B (patients 70-79 years old, n = 166), and group C (patients ≥ 80 years old, n = 75). Clinicopathologic characteristics as well as, short- and long-term outcomes were compared between the groups. RESULTS: The patients in groups B and C had more comorbidities, whereas the younger subjects (group A) had more advanced tumor stages. Less extensive surgery was performed in the groups B and C. Older patients (age ≥ 70 years) had more postoperative medical complications. Moreover, group C had a higher postoperative mortality rate (8.1%) than group A (1.8%) or group B (1.9%). In the multivariable analysis, age older than 80 years (group C) was a negative independent factor for overall survival (OS) (hazard ratio [HR], 2.36) compared with group A, whereas group B seemed to have a comparable risk (HR, 1.37). Notably, the three groups did not show significant differences in disease-related survival (DRS). CONCLUSION: The data suggest that patients 70-79 years of age show a risk of postoperative death comparable with that of younger subjects. However, patients older than 80 years should be carefully selected for surgical treatment due to the increased risk of postoperative mortality.

Western strategy for EGJ carcinoma.

In this paper, the epidemiological and clinicobiological behavior of esophagogastric junction (EGJ) adenocarcinoma in the West is compared and contrasted to that in the East, and an overview is provided of current therapeutic strategies employed for this type of tumor in Western countries. It is well known that multimodal treatment is the therapeutic standard in locally advanced EGJ adenocarcinoma, but whether neoadjuvant/perioperative chemotherapy (CT) or neoadjuvant chemoradiotherapy (CRT) is the optimal approach is still debated. Neoadjuvant CRT improves local control in locally advanced Siewert type I and II tumors, so it should be considered the treatment of choice. In the subset of these patients with microscopic systemic disease at diagnosis, more intensive exclusive chemotherapy protocols could be of benefit. Therefore, there is an urgent need to identify these patients before planning the treatment. For Siewert type III tumors, perioperative chemotherapy is the standard. While there is general agreement on the optimal surgical approach for Siewert types I and III (a two-field Ivor Lewis operation and a total gastrectomy with distal esophagectomy, respectively), no standard surgical treatment has been defined for Siewert type II tumors. When data from Western series on proximal and circumferential resection margins and on nodal spread in Siewert type II tumors are taken into account, the optimal surgical approach appears to be Ivor Lewis esophagectomy. Whether the extent of esophageal invasion can correctly predict nodal involvement in middle-upper mediastinal stations as a means to restrict indications for transthoracic esophagectomy requires further investigation in the West.

Targeted therapies for advanced and metastatic adenocarcinoma of the gastroesophageal junction: is there something new?

Despite improvements in systemic chemotherapy (CT), the prognosis of metastatic adenocarcinoma of the gastroesophageal junction remains poor. Over the years, new targeting agents have become available and were tested, with or without CT, in first or subsequent lines of therapy. The epidermal growth factor receptor family was targeted with monoclonal antibodies (MoAbs) (trastuzumab, cetuximab, panitumumab) and tyrosin kinase inhibitors (TKIs) (lapatinib, erlotinib, gefitinib). Only trastuzumab, in combination with cisplatin and fluoropyrimidines, significantly improved overall survival (OS) in first-line therapy (13.8 vs. 11.1 months). Angiogenesis also was targeted with MoAbs (bevacizumab and ramucirumab); ramucirumab, a vascular endothelial growth factor-receptor 2 antagonist, enhanced OS in two phase III studies in the first (9.6 vs. 7.4 months) and subsequent lines of treatment (5.2 vs. 3.8 months), while the bevacizumab study was negative. TKIs (sunitinib, sorafenib, regorafenib, apatinib) were tested in this setting in phase II studies in the second/third line, only showing modest antitumor activity. The hepatocyte growth factor receptor (MET) was targeted in untreated patients in a phase III trial with MoAb rilotumumab, with or without CT, but the study was stopped because of mortality excess in the rilotumumab arm. Mammalian target of rapamycin (MTOR) pathway inhibition with everolimus was tested in pretreated patients in a placebo-controlled phase III trial who failed to improve OS (5.4 vs. 4.3 months). In conclusion, considering the modest survival gain obtained overall, the high cost of these therapies and the quality of life issue must be primarily considered in treating these patients.

Gastric stump cancer after distal gastrectomy for benign disease: clinicopathological features and surgical outcomes.

PURPOSE: The purpose of the present study was to analyze clinicopathologic features and long-term prognosis of gastric stump cancer (GSC) arising in the remnant stomach 5 years or later after partial gastrectomy for benign disease. METHODS: We reviewed the results of 176 patients resected with curative intent for GSC at 8 Italian centers belonging to the Italian Research Group for Gastric Cancer (GIRCG). The median (range) follow-up time for surviving patients was 71.2 (6-207) months. RESULTS: One hundred forty-six patients were men, the mean age at the time of diagnosis was 69.2 years, and the great majority (167 cases) underwent Billroth II reconstruction. R0 resection was achieved in 158 (90 %) patients, and in 94 (53 %) lymph node dissection was ≥D2. Postoperative mortality and complication rates were 6.2 and 43.2 %, respectively. T1 tumor was diagnosed in 45 (25 %) cases. Lymph node metastases were evident in 86 patients (49 %). Thirteen patients had involvement of the jejunal mesentery nodes (pJN+); five cases were T2-T3 and eight cases were T4. Overall 5-year survival rate was 53.1 %. Five-year survival rates were 68.1, 37.8, and 33.1 % for pT1, pT2-3, and pT4 tumors, respectively (P = 0.001). Five-year survival rate was 56.5 % for node-negative tumors (pN0), 32.3 % for tumors with nodal metastases without involvement of jejunal mesentery nodes (pN+), and 17.1 % for tumors with involvement of jejunal mesentery nodes (pJN+) (P = 0.002). CONCLUSIONS: Our study suggests that an aggressive surgical approach can achieve a satisfactory outcome in GSC.

High-throughput mutation profiling identifies novel molecular dysregulation in high-grade intraepithelial neoplasia and early gastric cancers.

BACKGROUND: There is still no widely accepted molecular marker available to distinguish between gastric high-grade intraepithelial neoplasia (HG-IEN) and invasive early gastric cancer (EGC). METHODS: HG-IEN and EGC lesions coexisting in the same patient were manually microdissected from a series of 15 gastrectomies for EGC; 40 ng DNA was used for multiplex PCR amplification using the Ion AmpliSeq Cancer Panel, which explores the mutational status of hotspot regions in 50 cancer-associated genes. RESULTS: Of the 15 EGCs, 12 presented at least one somatic mutation among the 50 investigated genes, and 6 of these showed multiple driver gene somatic mutations. TP53 mutations were observed in 9 cases; APC mutations were identified in 3 cases; and ATM and STK11 were mutated in 2 cases. Seven HG-IEN lesions shared an identical mutational profile with the EGC from the same patient; 13 mutations observed in APC, ATM, FGFR3, PIK3CA, RB1, STK11, and TP53 genes were shared by both HG-IEN and ECG lesions. CDKN2A, IDH2, MET, and RET mutations were observed only in EGC. TP53 deregulation was further investigated in an independent series of 75 biopsies corresponding to all the phenotypic lesions occurring in the EGC carcinogenetic cascade. p53 nuclear immunoreaction progressively increased along with the dedifferentiation of the lesions (P < 0.001). Overall, 18 of 20 p53-positive lesions showed a TP53 mutated gene. DISCUSSION: Our results support the molecular similarity between HG-IEN and EGC and suggest a relevant role for TP53 in the progression to the invasive phenotype and the use of immunohistochemistry as a surrogate to detect TP53 gene mutations.

Influence of Tumor Stroma on the Aggressiveness of Poorly Cohesive Gastric Carcinoma.

Tumor-stroma crosstalk promotes the adaptation of cancer cells to the local microenvironment and sustains their growth. We assessed the quantitative and qualitative impact of intralesional stroma on clinic-pathological features and the prognosis of poorly cohesive gastric cancer (PCGC) variants. Tissue microarrays including 75 PCGC specimens were immunostained for cytokeratin 8/18 and α-smooth muscle actin to assess the relative proportion of neoplastic cells versus stromal components and the cases were subsequently divided into stroma-rich (SR) and stroma-poor (SP) tumors. Stromal status is significantly associated with the depth of tumor invasion. Patient survival rate was found to be higher in the SP compared to the SR tumor group and, hence, abundant stroma was identified as a significant risk factor in univariable analysis but had no independent prognostic impact. We also investigated the mRNA levels of KRT8 and the associated transcriptional signatures using the molecular data of 82 PCGC cases divided into KRT8-high and KRT8-low groups. KRT8-high tumors were enriched in proteins localized in the extracellular compartment and their expression levels correlated with longer survival in the KRT8-high group and shorter overall survival in the KRT8-low group. Comprehensively, we find that relative intralesional stromal content is a marker of aggressiveness in PCGC tumors and that extracellular proteins characterize functionally and clinically different PCGC subgroups.