Metastasis in para-aortic lymph nodes in patients with advanced gastric cancer, treated with extended lymphadenectomy.

BACKGROUND/AIMS: Lymph node dissection is an essential component of curative resection for advanced gastric cancer. To improve the survival of N2 patients, Asian surgeons have been performing D2+para-aortic lymph node dissection. The current study presents the results of lymph node status from multicenter trial of D2 and D2 + para-aortic nodal (No.16) dissection (D4 dissection). METHODOLOGY: Patients enrolled in the study had potentially curable gastric adenocarcinoma in an advanced stage, T2, T3 or T4/N1 or N2. Patients were randomized to undergo either D2 or D4 gastrectomy. RESULTS: Two hundred and seventy patients were registered and 136 and 134 patients were allocated into the D2 or D4 group, respectively. The average nodal yield of No.16 in D4 group was 18.4 +/- 14.1, ranging from 2 to 84. No.16 metastasis was detected in 12 (9.0%) of 134 D4 patients. One, 9 and 2 patients had simultaneous involvement in N1, N2, and N3 (No.8p, 12, 13 or 14). Namely, in 39 patients who were diagnosed as N2 from the lymph node status in N1 and N2 levels, nine (23.0%) patients had No.16 metastasis. The stage migration by D4 was found in 10 (7.5%). Logistic regression analysis revealed that the stations of No.7 and No.8 were the significant predictors of No.16 involvement. CONCLUSIONS: The present study may strongly suggest that prophylactic D4 dissection may be indicated for patients with N2 involvement, and that No.7 and No.8 are the junctional nodes for D4 dissection.

Proliferative activity of micrometastases in the lymph nodes of patients with gastric cancer.

BACKGROUND: Immunohistochemically detectable isolated tumour clusters (ITCs) with a diameter of less than 0.2 mm have been regarded as non-metastatic lesions, because of a lack of proliferative activity. This study investigated the proliferative activities of ITCs. METHODS: Three hundred and eight patients with primary gastric cancer diagnosed as pN0 by routine histological examination were studied. All patients underwent curative resection. Sections of lymph nodes were stained by double-immunostaining methods using anti-cytokeratin and anti-Ki-67 antibody (MIB-1). RESULTS: ITCs were detected in 77 nodes from 37 patients, designated as having pN0(i+) lesions. Seventy of 77 lymph nodes with ITCs were detected in the N1 station, and seven were found in the N2 station. Of 25 single isolated cancer cells, 12 showed positive labelling with MIB-1, and 49 of 52 ITCs with clusters of cancer cells had positive MIB-1 labelling (mean(s.d.) 46.6(30.1) per cent). Five of the 37 patients with ITCs (pN0(i+)) versus one of the 271 patients with no evidence of ITCs (pN0(i-)) died from recurrence. Patients with ITCs had a significantly worse prognosis than those without (P = 0.014). CONCLUSION: ITCs have a high proliferative activity and may have the potential to evolve into established lymph node metastasis.

The ectomycorrhizal fungus Scleroderma bermudense alleviates salt stress in seagrape (Coccoloba uvifera L.) seedlings.

The purpose of this study was to test the capacity of the ectomycorrhizal (ECM) fungus, Scleroderma bermudense, to alleviate saline stress in seagrape (Coccoloba uvifera L.) seedlings. Plants were grown over a range (0, 200, 350 and 500 mM) of NaCl levels for 12 weeks, after 4 weeks of non-saline pre-treatment under greenhouse conditions. Growth and mineral nutrition of the seagrape seedlings were stimulated by S. bermudense regardless of salt stress. Although ECM colonization was reduced with increasing NaCl levels, ECM dependency of seagrape seedlings increased. Tissues of ECM plants had significantly increased concentrations of P and K but lower Na and Cl concentrations than those of non-ECM plants. Higher K concentrations in the leaves of ECM plants suggested a higher osmoregulating capacity of these plants. Moreover, the water status of ECM plants was improved despite their higher evaporative leaf surface. The results suggest that the reduction in Na and Cl uptake together with a concomitant increase in P and K absorption and a higher water status in ECM plants may be important salt-alleviating mechanisms for seagrape seedlings growing in saline soils.

Operative morbidity and mortality after D2 and D4 extended dissection for advanced gastric cancer: a prospective randomized trial conducted by Asian surgeons.

BACKGROUND/AIMS: A randomized study was performed to evaluate morbidity and mortality after D2 (level 1 and 2 lymphadenectomy) and D4 (D2 plus lymphadenectomy of para-aortic lymph nodes) dissection for advanced gastric cancer. METHODOLOGY: Two hundred and fifty-six patients with advanced gastric adenocarcinoma were enrolled (128 to each group). Patients were randomly allocated into D2 (N = 128) or D4 (N = 128) group. The first and second tiers of lymph nodes are removed in D2 dissection. In D4 gastrectomy, the paraaortic lymph nodes were additionally removed. RESULTS: There was no indication of significant distribution bias with regard to age, sex, T-grade, and N-grade between the two groups. Operation time of D4 gastrectomy (369 +/- 120 min) was significantly longer than that of D2 gastrectomy (273 +/- 1103 min), and blood loss of the D4 group (872 +/- 683 mL) was significantly greater than that of the D2 group 571 +/- 527 mL (P < 0.001). Five (4%) and two (2%) medical complications developed in the D2 and D4 groups, respectively. Surgical complications developed in 28 (22%) and 48 patients (38%) after D2 and D4 gastrectomy. The most common complications were anastomotic leakage, pancreatic fistula, and abdominal abscess. Pancreatic fistula developed in 6 (19%) of 32 patients after D4 plus pancreatosplenectomy, but the incidence of pancreatic fistula after D2 gastrectomy plus pancreatosplenectomy was low (6%, 1/16). Two patients died within 30 days of operation (0.8%, 2/256), and each patient belonged to the D2 and D4 group. CONCLUSIONS: Although there is a significantly higher surgical complication rate in D4 dissection, D4 dissection can be done safely as D2 dissection when performed by well-trained surgeons.

Neoadjuvant treatment of gastric cancer with peritoneal dissemination.

AIMS: To report our experience of neoadjuvant intraperitoneal and systemic chemotherapy (NIPS) for patients having a complete resection of the primary gastric cancer and peritoneal carcinomatosis (PC). PATIENTS AND METHODS: Patients with advanced peritoneal dissemination of primary gastric cancer had the placement of a peritoneal port system. For intraperitoneal chemotherapy, 40 mg of docetaxel and 150 mg of carboplatin were introduced in 1000 ml of saline on a weekly basis. Simultaneously, 100 mg/m2 of methotrexate and 600 mg/m2 of 5-fluorouracil were infused via a peripheral vein. A minimum of two cycles and up to six cycles of NIPS were used prior to cancer resection. At surgery a complete removal of the primary gastric cancer and the peritoneal implants by peritonectomy was attempted. RESULTS: Sixty-one patients were enrolled in the study. Thirty-nine had positive intraperitoneal cytology which reverted to negative cytology after treatment in 22. Thirty-eight showed a partial response. Thirty patients came to resection and 14 patients could be made disease-free. Median survival time of all patients was 14.4 months. Patients who received a complete resection had a median survival time of 20.4 months. Grade III/IV toxicities were not found after two courses of NIPS, but did develop in seven patients after more than three courses of NIPS. CONCLUSION: NIPS can downstage large volume peritoneal dissemination of gastric cancer. When combined with gastrectomy including peritonectomy a complete surgical resection was possible in one-quarter of the patients and resulted in a prolonged survival. This combined intraperitoneal and systemic chemotherapy for PC from gastric cancer is worthy of consideration for phase III clinical investigations.

Quantitative prognostic indicators of peritoneal dissemination of gastric cancer.

There are three classifications that describe the quantitative prognostic indicators of peritoneal dissemination for gastric cancer. The Japanese classification (P1, P2, and P3, Lyon classification, (stage I, II, stage III, and stage IV), and the Peritoneal Cancer Index (PCI). Carcinomatosis with limited extent (P1/ P2) corresponds to the PCI less than 13 and the stage I and II from Lyon classification. Carcinomatosis with large extent (P3) corresponds to PCI of 13 or larger and stage III and IV from Lyon classification. PCI enables one to describe the precise distribution of peritoneal dissemination. All three classifications correlate with prognosis. With regard to the surgical cytoreduction of the primary tumor and the peritoneal dissemination, Sugarbaker proposed the classification of completeness of cytoreduction (CCR). Patients with no macroscopic residual tumor had significantly better prognosis than those with residual disease. CCR is a valuable prognostic indicator after cytoreductive surgery.

Treatment of peritoneal dissemination from gastric cancer by peritonectomy and chemohyperthermic peritoneal perfusion.

BACKGROUND: There is no standard treatment for peritoneal dissemination from gastric cancer. A novel treatment consisting of peritonectomy and intraoperative chemohyperthermic peritoneal perfusion (CHPP) was compared with conventional surgery and CHPP. METHODS: Records of all patients who underwent CHPP after cytoreductive surgery between 1992 and 2002 were reviewed. RESULTS: Data for 107 patients with peritoneal dissemination were available. Complete cytoreduction was achieved in 47 (43.9 per cent) of the 107 patients: 18 of 65 who underwent conventional surgery and 29 of 42 who had peritonectomy. Twenty-three patients (21.5 per cent) suffered from complications. The overall operative mortality rate was 2.8 per cent. Seventeen patients (15.9 per cent) were disease free and 87 subsequent deaths were related to disease progression. The median survival for all patients was 11.5 months, with a 5-year survival rate of 6.7 per cent. Median survival after complete cytoreduction was 15.5 months and that after incomplete cytoreduction was 7.9 months, with 5-year survival rates of 13 and 2 per cent respectively. Completeness of cytoreduction and peritonectomy were independent prognostic factors. The 5-year survival rate after complete cytoreduction by peritonectomy with CHPP was 27 per cent. CONCLUSION: Complete cytoreduction after peritonectomy and CHPP may improve the survival of patients with peritoneal dissemination from gastric cancer.

Influence of micrometastasis on N stage in gastric cancer and clinical application.

In order to evaluate the real extent of lymph node metastasis (LNM) in gastric cancer, an immunohistochemical (IHC) analysis was performed. We examined 11173 lymph nodes removed from 355 patients with all stages of gastric carcinoma. Tissue preparations were stained with cytokeratin 18, monoclonal antibody against cytokeratin. Micrometastases were found in 2.5% of the lymph nodes and in 31.3% of patients. The incidence of the patients with LNM increased to 9.1% in T(1m) (n = 99), 31.6% in T(1sm) (n = 95, 23.1% in sm1, 34.8% in sm2), 66.7% in T2 (n = 108, 48.8% in mp, 76.5% in ss), 88.1% in T3 (n = 42), and 90.9% in T4 (n = 11) lesions. Upstage was identified in 8.5% of patients: 6.7% in T1 (4.0% in m, 7.7% in sm1, 10.1% in sm2), 14.8% in T2 (20% in mp, 11.8% in ss), 2.4% in T3, and 0% in T4. Factors related to LNM were: tumor size and lymphatic invasion in mucosal lesions; only lymphatic invasion in submucosal lesions; size and depth of tumor, and lymphatic invasion in T2 lesions. In conclusion, the incidence of micrometastasis in regional lymph nodes was higher than we imagined in T1 lesions, more than D1 lymphadenectomy for sm1 and selected cases of mucosal cancer, and D2 lymphadenectomy for sm2 are necessary.

Limited pollen dispersal and biparental inbreeding in Symphonia globulifera in French Guiana.

In this paper, we report a study of the mating system and gene flow of Symphonia globulifera, a hermaphroditic, mainly bird-pollinated tree species with a large geographic distribution in the tropical Americas and Africa. Using three microsatellites, we analysed 534 seeds of 28 open pollinated families and 164 adults at the experimental site 'Paracou' in French Guiana. We observed, compared to other tropical tree species, relatively high values for the effective number of alleles. Significant spatial genetic structure was detected, with trees at distances up to 150 m more genetically similar than expected at random. We estimated parameters of the mating system and gene flow by using the mixed mating model and the TwoGener approach. The estimated multilocus outcrossing rate, tm, was 0.920. A significant level of biparental inbreeding and a high proportion of full-sibs were estimated for the 28 seed arrays. We estimated mean pollen dispersal distances between 27 and 53 m according to the dispersal models used. Although the adult population density of S. globulifera in Paracou was relatively high, the joint estimation of pollen dispersal and density of reproductive trees gave effective density estimates of 1.6 and 1.3 trees/ha. The parameters of the mating system and gene flow are discussed in the context of spatial genetic and demographic structures, flowering phenology and pollinator composition and behaviour.

Long-distance pollen flow and tolerance to selfing in a neotropical tree species.

Outcrossing rates, pollen dispersal and male mating success were assessed in Dicorynia guianensis Amshoff, a neotropical tree endemic to the Guiana shield. All adult trees within a continuous area of 40 ha (n = 157) were mapped, and were genotyped with six microsatellite loci. In addition, progenies were genotyped from 22 mature trees. At the population level, the species was mostly outcrossing (tm = 0.89) but there was marked variation among individuals. One tree exhibited mixed mating, confirming earlier results obtained with isozymes that D. guianensis can tolerate selfing. A Bayesian extension of the fractional paternity method was used for paternity analysis, and was compared with the neighbourhood method used widely for forest trees. Both methods indicated that pollen dispersal was only weakly related to distance between trees within the study area, and that the majority (62%) of pollen came from outside the study stand. Using maximum likelihood, male potential population size was estimated to be 1119, corresponding to a neighbourhood size of 560 hectares. Male mating success was, however, related to the diameter of the stem and to flowering intensity assessed visually. The mating behaviour of D. guianensis is a combination of long-distance pollen flow and occasional selfing. The species can still reproduce when it is extremely rare, either by selfing or by dispersing pollen at long distances. These results, together with the observation that male mating success was correlated with the size of the trees, could be implemented in management procedures aiming at regenerating the species.

Nuclear and chloroplast genetic structure indicate fine-scale spatial dynamics in a neotropical tree population.

Dicorynia guianensis is a canopy tree, endemic to the tropical rain forest of French Guiana. We compared generational and spatial genetic structure for maternally and biparentally inherited markers in two cohorts (adult and seedling) in order to infer processes shaping the distribution of genetic diversity. The study was conducted on a 40 ha study plot located at Paracou near Kourou, where 172 adults trees and 375 saplings were sampled. Aggregation of trees was therefore suggested at different distances, ranging from 100 to 400 m. There was a strong link between demographic and genetic spatial structures at small distances (less than 100 m) that is likely to be the consequence of restricted seed dispersal. Genetic differentiation was more pronounced between spatial aggregates than between cohorts. Despite the spatial differentiation, the species was able to maintain high levels of diversity for maternal genomes, suggesting rapid turnover of aggregates. Spatial autocorrelation was larger for chloroplast than nuclear markers indicating a strong asymmetry between pollen and seed flow. Fixation indices indicated a lower heterozygote deficiency for the adults, maybe because of gradual elimination of selfed trees. Genetic relatedness at lower distances was higher in adult trees than in saplings, as a result of generation overlapping in the adult cohort. Overall, our results confirm earlier biological knowledge about the dispersion mechanisms of the species, and lead to an enhanced role of spatial processes in the dynamics of genetic diversity of D. guianensis.

Fine-scale spatial genetic structure of eight tropical tree species as analysed by RAPDs.

The fine-scale spatial genetic structure of eight tropical tree species (Chrysophyllum sanguinolentum, Carapa procera, Dicorynia guianensis, Eperua grandiflora, Moronobea coccinea, Symphonia globulifera, Virola michelii, Vouacapoua americana) was studied in populations that were part of a silvicultural trial in French Guiana. The species analysed have different spatial distribution, sexual system, pollen and seed dispersal agents, flowering phenology and environmental demands. The spatial position of trees and a RAPD data set for each species were combined using a multivariate genetic distance method to estimate spatial genetic structure. A significant spatial genetic structure was found for four of the eight species. In contrast to most observations in temperate forests, where spatial structure is not usually detected at distances greater than 50 m, significant genetic structure was found at distances up to 300 m. The relationships between spatial genetic structure and life history characteristics are discussed.

Diagnostic value of preoperative RT-PCR-based screening method to detect carcinoembryonic antigen-expressing free cancer cells in the peritoneal cavity from patients with gastric cancer.

BACKGROUND: At present the most reliable method for the diagnosis of peritoneal micrometastasis of gastric cancer is peritoneal wash cytology, but the sensitivity of this method is low. The aim of the present study was to verify whether carcinoembryonic antigen (CEA) reverse transcriptase-polymerase chain reaction (RT-PCR) assay can enhance the sensitivity and specificity of conventional cytology, and to determine how this technique can improve the accuracy of peritoneal recurrence. METHODS: The present study included 230 patients with gastric cancer. Preoperative peritoneal wash was done by a paracentesis, followed by conventional cytology, CEA measurement, and CEA RT-PCR of recovered fluid. RESULTS: The CEA RT-PCR assay yielded 40 (17%) positives, which included none of the 26 patients with benign disease. The incidence of positive cytology and CEA level in wash fluid was 19% and 15%, respectively. Logistic stepwise regression analysis revealed that lymph node status, depth of invasion, venous invasion, and the results of peritoneal cytological examination, and CEA RT-PCR assay were independently related to peritoneal recurrence. The CEA level in the wash fluid was not related to peritoneal recurrence. Peritoneal cytological examination was the most significant predictive factor for peritoneal recurrence with a sensitivity of 46%, specificity of 94% and accuracy of 73%, while the corresponding values of the CEA RT-PCR assay were 31%, 95%, and 73%. Combining cytological examination with CEA RT-PCR assay resulted in a sensitivity rate for peritoneal recurrence of 57%, an 11% improvement over that of cytology alone. CONCLUSION: The data indicate that the use of a combination of CEA RT-PCR and cytological assay is more likely to identify patients who will develop peritoneal recurrence. This may be useful for the classification of patients for the most suitable therapeutic trials.

Prediction of peritoneal micrometastasis by peritoneal lavaged cytology and reverse transcriptase-polymerase chain reaction for matrix metalloproteinase-7 mRNA.

PURPOSE: Peritoneal dissemination is the most common cause of death associated with gastric cancer. In this study, we report the significance of molecular diagnosis of peritoneal dissemination by means of matrix metalloproteinase-7 (MMP-7) reverse transcriptase-PCR (RT-PCR) assay using preoperative peritoneal wash fluid. EXPERIMENTAL DESIGN: Preoperative peritoneal lavage by paracentesis was performed on 152 patients with gastric cancer. The peritoneal lavaged fluid was subjected to RT-PCR analysis with primers specific for MMP-7 and conventional cytological Papanicolaou examination. RESULTS: The MMP-7 RT-PCR assay was able to detect cancer cells at densities even lower than 10 cells/sample. There was no signal of MMP-7 mRNA from mesothelial cells, fibroblasts, peripheral blood, and lavaged fluid from patients with benign disease. Cytological examination and MMP-7 RT-PCR assay results were positive for 27 (18%) and 28 (18%) samples, respectively. The sensitivity for the prediction of peritoneal dissemination by cytology and MMP-7 RT-PCR assay were 46% and 33%, but the combination analysis using both parameters improved the sensitivity rate with 62%. Logistic regression analysis revealed that the cytological examination and MMP-7 RT-PCR assay are independent predictors of peritoneal dissemination. CONCLUSION: The combination of cytological examination and RT-PCR assay of preoperative peritoneal lavaged fluid is a highly efficient and reliable method for the selection of patients for adjuvant i.p. chemotherapy.

Intraoperative chemohyperthermic peritoneal perfusion as an adjuvant to gastric cancer: final results of a randomized controlled study.

BACKGROUND/AIMS: Although the most frequent cause of death after curative resection of advanced gastric cancer is peritoneal recurrence, there was no effective therapy for the prevention of peritoneal recurrence. This randomized trial sought to determine whether intraoperative chemohyperthermic peritoneal perfusion could eliminate microscopic residual disease and thereby improve survival of patients with advanced gastric cancer. METHODOLOGY: One-hundred and thirty-nine patients with T2-4 gastric cancer underwent curative gastrectomy with extended lymphadenectomy. These patients were randomly allocated into the following three groups. Patients in the CHPP group received surgery + chemohyperthermic peritoneal perfusion, and those in the CNPP group underwent surgery + chemonormothermic peritoneal perfusion. The third group was surgery alone group. In the CHPP and CNPP groups, peritoneal cavity was perfused with 6-8 liters of heated saline at, respectively, 42-43 degrees C and 37 degrees C with 30 mg of mitomycin C and 300 mg of cisplatin by a extracorporeal circulation machine. RESULTS: Major operative complication occurred in 19% (9/48), 14% (6/44) and 19% (9/47) of the CHPP, CNPP and surgery alone group, respectively. Complication which uniquely developed after chemohyperthermic peritoneal perfusion was bowel perforation. Mortality rates of each group were 4% (2/48), 0% (0/44) and 4% (2/47) in the CHPP, CNPP and surgery alone group, respectively. Overall 5-year survival rates of CHPP, CNPP and surgery alone groups were 61%, 43% and 42%, respectively. In a subset analysis, patients with gastric cancer having serosal invasion or lymph node metastasis have shown a statistically significant improvement in survival when treated with chemohyperthermic peritoneal perfusion. However, chemonormothermic peritoneal perfusion had no survival benefit. By analyzing with Cox proportional hazard model, chemohyperthermic peritoneal perfusion emerged as an independent prognostic factor for good survival. Surgery alone had three-fold higher risk of death than chemohyperthermic peritoneal perfusion. CONCLUSIONS: Chemohyperthermic peritoneal perfusion had an efficiency for the prophylaxis of recurrence after curative resection of advanced gastric cancer, and is indicated for patients with tumor infiltrating beyond serosal layer and node positive tumor.

Inverse expression of S100A4 and E-cadherin is associated with metastatic potential in gastric cancer.

S100A4 is known to be involved in cancer cell motility by virtue of its ability to activate nonmuscle myosin. E-cadherin has an important role in the homophilic cell-cell adhesion and is called an invasion suppressor gene. In the current study, we investigate the histological type and metastatic potential of gastric cancer from the aspect of the interrelationship of E-cadherin and S100A4 expression. Expression of E-cadherin and S100A4 in gastric cancer cell lines, primary gastric cancers, and their normal counterparts were analyzed by reverse transcription-PCR, Western blot, and immunohistochemical methods. S100A4 protein and E-cadherin were expressed in five of eight gastric cancer cell lines, and inverse expression of the two proteins are found in four cell lines. In the clinical specimens, E-cadherin mRNA expression in differentiated adenocarcinomas (88%, 14 of 16) was significantly more frequent than that in poorly differentiated adenocarcinomas (50%, 22 of 44; P = 0.015). Western blot analysis demonstrates that S100A4 protein expression in poorly differentiated adenocarcinomas was 1.6-fold higher than in well differentiated adenocarcinoma. Immunohistochemically, S100A4 expression was detected in 51 (55%) of 92 primary gastric cancers. Reduced expression of E-cadherin in primary tumors was found in 66 (72%) of 92 tumors. S100A4 expression in the poorly differentiated adenocarcinomas had a strong relation to positive lymph node involvement or peritoneal dissemination. Reduced E-cadherin expression showed a strong relationship with positive serosal involvement and infiltrating type. Tumors classified as a group with reduced E-cadherin and high expression of S100A4 reveal positive peritoneal dissemination, serosal involvement, and infiltrating type in the growth pattern. Furthermore, these tumors showed a strong correlation with the poorly differentiated adenocarcinoma. In contrast, tumors with preserved E-cadherin and low expression of S100A4 have a close relation to the well differentiated adenocarcinoma and a favorable prognosis. By the Cox proportional hazard model, S100A4 and E-cadherin tissue status was judged as an independent prognostic factor. S100A4 and E-cadherin tissue status may be a powerful aid in evaluating metastatic potential or the prognosis of patients with gastric cancer.

Spatial and temporal distribution of chloroplast DNA polymorphism in a tropical tree species.

The level and the spatial organization of chloroplast DNA polymorphism were investigated in Dicorynia guianensis Hamshoff (Caesalpiniaceae) at different spatial and temporal scales. D. guianensis is a canopy tree of the rain forest that is distributed throughout the Guiana plateau in small aggregates. Twelve different haplotypes were identified using restriction analysis of polymerase chain reaction (PCR) amplified fragments of the chloroplast genome. When populations from different areas of French Guiana were compared, a clear geographical pattern of haplotype frequencies was identified along the Atlantic coast. This pattern is most likely the result of the restriction-expansion dynamics of the tropical forest during the Quaternary. At the local level, D. guianensis was characterized by a high level of within population diversity. Maintenance of within population diversity results from the dynamics of the aggregates; stochastic demography associated with the turnover of aggregates generates genetic differentiation among them. At the stand level, a strong spatial aggregation of haplotypes persisted from the adult to the seedling cohort indicating limited seed flow. There was also a strong difference in levels of diversity between the cohorts which suggested that recruitment over several years is needed in order to maintain genetic diversity during regeneration.

Postoperative results of left upper abdominal evisceration for advanced gastric cancer.

BACKGROUND/AIMS: In spite of the improvement of surgical techniques, the prognosis of patients with advanced gastric cancer still remains poor. With the aim of achieving en bloc resection of primary tumor, peritoneal dissemination on the greater omentum and lymph node metastasis, left upper abdominal evisceration (LUAE) was performed for 75 patients. In this report, we investigated the prognostic difference between the LUAE group and standard gastrectomy (total gastrectomy + pancreatosplenectomy). METHODOLOGY: In the LUAE group, total gastrectomy was performed with the en bloc resection of the transverse colon, pancreas body and tail, spleen and left adrenal gland. In addition, omental bursa, covering retroperitoneum and pancreas body and tail was resected in combination with greater omentum, transverse mesocolon, and lesser omentum. RESULTS: There were 3 (4.1%) postoperative death in the LUAE group, and 2 (1.7%) in the control group. However, there was no statistical difference in the incidence of postoperative complications between these 2 groups. The overall 5-year survival rates of the LUAE and control groups were 33% and 39%, respectively. There was no statistical survival difference between these 2 groups. Survival difference between the LUAE and control group was not found in terms of tumor location, wall invasion, lymph node status, peritoneal dissemination, and macroscopic type. CONCLUSIONS: From these results, LUAE cannot improve the survival of patients with advanced gastric cancer. Consequently, LUAE should be indicated for T4 tumors, which directly invade into the transverse colon.

Membrane-type 1 matrix metalloproteinase enhances lymph node metastasis of gastric cancer.

The mechanisms of the lymph node metastasis remain unclear. We demonstrate the role of MT1-MMP on the lymph node metastasis using in vivo experimental model of lymph node metastasis by orthotopic implantation of MT1-MMP transfected gastric cancer cell line in the stomach of nude rats. TMK-1 cell line without expression of MT1-MMP was transfected with the pcDNA3 plasmid containing a 3.4-kb MT1-MMP cDNA fragment by calcium phosphate method, and the transfected cell line was designated as TMK-MT. Western blot and RT-PCR analyses showed the specific bands corresponding to MT1-MMP in the TMK-MT cells. By gelatin zymography, the activated form (62-kDa) of MMP-2 was identified in the medium of TMK-MT cell line, but was not detected in TMK-1 cells. Six weeks after orthotopic implantation of TMK-1 and TMK-MT xenografts of nude mouse-subcutaneus tumor into the stomach of nude rats, gastric tumors were found in all the animals. Histologically, the lymphatic invasion was found in the submucosa of the TMK-MT gastric tumors. Lymph node metastasis was not detected in nude rats bearing TMK-1 gastric tumor (0/8). In contrast, lymph node metastasis was detected in five out of 8 rats, bearing TMK-MT gastric tumor. MT1-MMP immunoreactivity was found on the cell membrane and cytoplasm of TMK-MT cells not only in the lymph node metastasis but also in the stomach tumor. These results suggest that MT1-MMP overexpression induced by transfection of its gene may promote lymph node metastasis of transformed cells.

Role of vascular endothelial growth factor C expression in the development of lymph node metastasis in gastric cancer.

Neogenesis of lymphatic vessel and lymphatic invasion is frequently found in the stroma of cancers, but the mechanisms of this phenomenon remain unclear. Vascular endothelial growth factor C (VEGF-C) is known to be the only growth factor for the lymphatic vascular system, and its receptor has been identified as Flt4. To clarify the mechanism of lymphatic invasion in cancer, we studied the expression of VEGF-C and flt4 genes in gastric cancer tissues. VEGF-C mRNA was mainly expressed in primary tumors (15 of 32; 47%), but the frequency of VEGF-C mRNA expression was low in normal mucosa (4 of 32; 13%). In primary tumors, there was a significant relationship between VEGF-C and flt4 mRNA expression. In contrast, Flt4 was mainly expressed on the lymphatic endothelial cells but not in cancer cells. A strong correlation was found between VEGF-C expression and lymph node status, lymphatic invasion, venous invasion, and tumor infiltrating patterns. Cancer cells in the lymphatic vessels frequently showed intracytoplasmic VEGF-C immunoreactivity. Furthermore, there was a close correlation between VEGF-C tissue status and the grade of lymph node metastasis. Patients with high expression of VEGF-C protein had a significantly poorer prognosis than did those in low VEGF-C expression group. By the Cox regression model, depth of wall invasion, lymph node metastasis, and VEGF-C tissue status emerged as independent prognostic parameters, and the VEGF-C tissue status was ranked third as an independent risk factor for death. These results strongly suggest that cancer cells producing VEGF-C may induce the proliferation and dilation of lymphatic vessels, resulting in the development of invasion of cancer cells into the lymphatic vessel and lymph node metastasis.