Yoshinari Mochizuki

Endoscopic ultrasound-guided fine-needle aspiration biopsy for the diagnosis of gastrointestinal stromal tumors in the stomach.

BackgroundFor the diagnosis of gastric submucosal tumors (SMTs), endoscopic ultrasound (EUS) alone does not reveal the complete pathology, such as the degree of malignancy, and EUS-guided fine-needle aspiration biopsy (EUS-FNAB) has been reported to be more useful. Recently, most cases initially diagnosed as leiomyosarcomas have received further study with immunohistochemical staining and have been given the new diagnosis of gastrointestinal stromal tumors (GISTs). The degree of malignancy of GISTs differs widely in clinical aspects. In this study, we examined whether EUS-FNAB was useful in diagnosing GISTs and differentiating their degrees of malignancy.MethodsFrom January 1997 to March 2002, 21 cases of gastric GISTs were diagnosed from the immunohistochemical staining of specimens resected at Aichi Cancer Center Hospital. Of these 21 patients, 14 (5 with high-grade malignancy and 9 with low-grade malignancy) underwent EUS-FNAB preoperatively, and were examined further: their EUS-FNAB specimens were submitted for additional immunohistochemical testing.ResultsThe EUS-FNAB specimens from all patients were positive for c-kit and CD34 immunohistochemical testing, coinciding with the staining results of the resected specimens. The MIB-1 labeling indices in specimens of high-grade malignancy were significantly higher than those of low-grade malignancy. If we assumed that a tumor with an MIB-1 labeling index of more than 5% was a high-grade malignancy, the diagnostic accuracy was 85.7%.ConclusionsThe EUS-FNAB procedure is a useful tool for diagnosing GISTs of the stomach with immunohistochemical staining. When used with MIB-1 staining, the procedure may indicate GIST prognosis and influence decisions regarding therapeutic strategies.

Follow-up surveillance for recurrence after curative gastric cancer surgery lacks survival benefit.

AbstractBackground: Although routine follow-up to detect asymptomatic recurrence after surgery for gastric cancer is recommended, the effect of such reassessment on survival has not been evaluated. Methods: Clinical records of patients developing recurrent disease after potentially curative resection between 1985 and 1996 were retrieved. Among these patients, 197 were in our follow-up program. We analyzed survival in these patients according to the presence or absence of cancer-related symptoms when recurrent disease was diagnosed. Results: Of all patients with recurrent disease, 50% were diagnosed within 1 year and 75% within 2 years of surgery. Asymptomatic recurrence, detected in 88 patients (45%), frequently represented distant metastasis. Although early detection significantly improved survival after detection of recurrent disease, disease-free survival for this subset was shorter. Thus, no significant difference in overall survival was observed. Conclusions: Early detection of asymptomatic gastric cancer recurrence did not improve overall survival of patients with recurrence after curative resection. Until development of more effective treatment for this disease, close follow-up may offer no survival benefit.

TNF-α promotes progression of peritoneal metastasis as demonstrated using a green fluorescence protein (GFP)-tagged human gastric cancer cell line

The mechanisms underlying progression of peritoneal metastasis by gastric cancer after micrometastasis formation remain unclear. In the present study, we investigated metastasis to the abdominal wall peritoneum, one of the major features of peritoneal spread, using a human gastric cancer cell line (GCIY-EGFP) tagged with the green fluorescence protein gene (GFP). This model allows sensitive, specific and sequential observation of metastasis development from the initial deposits to peritoneal carcinomatosis at the end stage. In the initial phase, GCIY-EGFP cells could form micrometastasis selectively on the omentum and mesenterium in a milky spot-dependent manner, but not on abdominal wall peritoneum lacking milky spots until the late stages. In vitro analysis using primary mesothelial cells revealed addition of TNF-α to decrease their stress fibers, leading to morphological change followed by exposure of the submesothelial extracellular matrix (ECM) in intercellular gaps. Such TNF-α pretreatment was found to enhance attachment of tumor cells to the mesothelial monolayer. When tumor cells were injected into the peritoneal cavity of TNF-α pretreated mice, they could metastasize to the abdominal wall peritoneum from the very early stages, resulting in accelerated accumulation of ascites than in TNF-α non-pretreatment controls. RT-PCR analysis revealed that tumor cells express cytokines and chemokines, including TNF-α. Furthermore, TNF-α treatment results in up-regulation of expression of monocyte chemoattractant protein-1(MCP-1) and IL-8 by mesothelial cells and of TNF-α itself by inflammatory leukocytes in the peritoneal cavity. These results suggest that metastasis to the abdominal wall peritoneum occurs as a second step from the first omental metastasis in a milky spot-independent manner and that TNF-α derived from tumor cells, mesothelial cells and inflammatory leukocytes in the peritoneal cavity may be involved in the progression of peritoneal metastasis.

Laparoscopic Wedge Resection for Gastrointestinal Stromal Tumors of the Stomach: Initial Experience

PurposeSurgery for gastrointestinal stromal tumors (GIST) of the stomach is now frequently performed using a laparoscopic approach. We investigated the feasibility and effectiveness of laparoscopy in the management of GIST of the stomach.MethodsWe reviewed the records of 12 consecutive patients who underwent laparoscopic surgery for GIST between April 2000 and April 2004, and compared their short-term outcomes with those of patients who underwent open surgery. All laparoscopic wedge resections were done using stapling devices and 3–4 trocars, often with the aid of intraoperative gastroscopy. We examined all patients preoperatively using various diagnostic modalities, including endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA). A laparoscopic approach was not indicated if the tumor was located near the cardia or pylorus or if it was ≧5 cm in diameter.ResultsA specific diagnosis of GIST was obtained preoperatively by EUS-FNA in 10 of the 12 patients. The median diameter of the lesion was 2.7 cm (range, 1.5–4.8 cm). Although intraoperative complications were encountered in two patients, conversion to open surgery was not required, and we were able to perform complete tumor excision with negative surgical margins in all patients. The median operative time was 100 min (range, 65–180 min), similar to that for open surgery. First flatus was passed earlier, and the interval to resuming oral intake was shorter than after open surgery. No major postoperative complications such as leakage developed, and the median postoperative hospital stay was 7 days (range, 5–12 days). All diagnoses made by EUS-FNA were confirmed by immunohisto-pathological evaluation of resected specimens.ConclusionLaparoscopic wedge resection is a feasible treatment option for GISTs of the stomach if the lesion is <5 cm in diameter.

Treatment and Risk Factors for Recurrence after Curative Resection of Gastrointestinal Stromal Tumors of the Stomach

The current definitive treatment for gastrointestinal stromal tumor (GIST) of the stomach is complete resection. GIST has a highly variable clinical course, and recurrent disease sometimes develops despite curative treatment. Although several known risk factors for recurrence exist, adequate treatment strategies are lacking. This study evaluated factors associated with relapse after curative treatment. Sixty patients with gastric GIST were identified from a hospital disease registry database. Clinicopathologic characteristics of these patients were reviewed and the Cox proportional hazards regression analysis was used to identify recurrent risk factors. With a median follow-up of 60 months (range 5–286 months), recurrence occurred in eight (13%) patients, three of whom underwent resection of the recurrent disease and are alive to date. Univariate analysis demonstrated that invasion of the adjacent organs (p = 0.0005), tumor size (p = 0.0046), and expression of proliferative markers [MIB-1 proliferative index (PI) ≥ 10%] (p = 0.0001) were significant risk factors for recurrence. Multivariate analysis with these three factors as variables revealed that only MIB-1 PI was a significant independent risk factor for recurrence (p = 0.0051). In conclusion, surgical resection may be indicated whenever a recurrent GIST is considered resectable. A high MIB-1 PI was identified as an independent indicator of risk for recurrent disease following curative surgery.

Molecular basis for sensitivity and acquired resistance to gefitinib in HER2-overexpressing human gastric cancer cell lines derived from liver metastasis

Gastric cancer metastasised to the liver was found to overexpress HER2 at a significantly higher incidence than primary gastric cancers. The purpose of the present study was to investigate the possibility of molecular therapy targeting HER2 overexpression in gastric cancer liver metastasis. We developed three new HER2-overexpressing gastric cancer cell lines (GLM-1, GLM-2, GLM-4) without epidermal growth factor receptor (EGFR) mutations derived from such liver metastasis, two of which had HER2 gene amplifications. All these GLM series of cell lines were highly sensitive to gefitinib in vitro, a specific inhibitor of EGFR tyrosine kinase (Iressa) rather than anti-HER2 antibody trastuzumab (Herceptin), whereas most of the HER2 low-expressing counterparts were not. In these HER2-overexpressing GLM series, protein kinase B (Akt), but not extracellular signal-regulated kinase 1/2 (ERK1/2), was constitutively phosphorylated, and gefitinib efficiently inhibited this Akt phosphorylation, induced strong apoptosis in vitro and exhibited antitumour activity in tumour xenografts in nude mice. This gefitinib-mediated antitumour effect in xenograft was significantly potentiated by trastuzumab treatment. On the other hand, gefitinib-resistant cells (GLM-1R) exhibited increased EGFR expression, followed by constitutive activation of mitogen-activated protein kinase (MAPK) pathway. These results suggest that the antitumour effect of gefitinib is due to the effective inhibition of HER2-driven constitutive activation of phosphatidylinositol-3-kinase (PI3K)/Akt pathway, and that the acquired resistance to gefitinib is due to the constitutive activation of Ras/MAPK pathway in compensation for PI3K/Akt pathway. Gastric cancer liver metastasis with HER2 overexpression would be a potential molecular target for gefitinib and trastuzumab.

A phase II study of radical surgery followed by postoperative chemotherapy with S-1 for gastric carcinoma with free cancer cells in the peritoneal cavity (CCOG0301 study)

BACKGROUND Patients with gastric cancer who have positive cytologic results for cancer cells in peritoneal washings (CY1) have poor outcomes, even in the absence of other distant metastases. A standard treatment for such patients remains to be established. METHODS We conducted a phase II trial with the 2-year survival rate as the primary endpoint. Patients who had gastric cancer with CY1 status but no other residual disease received postoperative chemotherapy with S-1 (1M tegafur-0.4M gimestat-1M otastat potassium) at a daily dose of 80mg/m(2) for 4 weeks, followed by 2 weeks of rest. This cycle was continued until disease progression or intolerable adverse events. D2 dissection was the recommended surgical procedure; splenectomy could be omitted at the discretion of the surgeon. Accrual of 50 patients was planned, and a 2-year survival rate of more than 36% was needed to exceed the historical control. RESULTS Forty-eight patients were enrolled, among whom 47 were assessable for survival and 46 for adverse reactions. Median overall survival was 705 days, and progression-free survival was 376 days. The 2-year survival rate was 47%. Median time to treatment failure was 288 days. Neutropenia was the commonest > or = grade 3 toxicity (6 patients), and anorexia was the most frequent > or = grade 2 non-hematologic toxicity (10 patients). CONCLUSIONS Gastrectomy followed by S-1 monotherapy resulted in survival that surpassed historical data and can serve as an active control treatment for future trials in patients who have gastric cancer with CY1 status in the Far East.

Prospective validation of quantitative CEA mRNA detection in peritoneal washes in gastric carcinoma patients

Prediction of peritoneal relapse is extremely important for gastric cancer patients after curative surgery. The present study prospectively validates the prognostic ability of quantifying carcinoembryonic antigen (CEA) mRNA in peritoneal washes by real-time reverse transcriptase–polymerase chain reaction. Based on a retrospective study of 197 curatively resected gastric cancer patients (training set), we determined a cutoff value of CEA mRNA using receiver-operating characteristic curve. We used this cutoff value to validate the risk of peritoneal recurrence in a new cohort of 86 gastric cancer patients (validation set) between July 2000 and December 2002 in a prospective study. During the median 30 months of postoperative surveillance, 20 of the 86 patients died, and 13 of the 20 developed peritoneal metastases. Peritoneal recurrence-free survival as well as overall survival was significantly worse in patients with positive CEA mRNA (P<0.0001). Multivariate analysis with the Cox proportional hazards model showed that positive CEA mRNA was a significant independent risk factor with both survival (P=0.0130) and peritoneal recurrence-free survival (P=0.0006) as end points. These results indicate that quantitation of CEA mRNA in peritoneal washes is a reliable prognostic indicator of peritoneal recurrence in the clinical setting.

Chemosensitivity of peritoneal micrometastases as evaluated using a green fluorescence protein (GFP)-tagged human gastric cancer cell line

The Chemosensitivity of micrometastases in the peritoneal cavity to a 5‐fluorouracil derivative (TS‐1) was examined with a micrometastasis model featuring a human gastric cancer cell line tagged with the green fluorescence protein (GFP) gene in nude mice. Peritoneal metastases on the omentum and mesentery could be specifically visualized even when minute or dormant and also externally monitored noninvasively under illumination with blue light from 1 day after intraperitoneal (i.p.) injection of tumor cells. Metastatic deposits formed after i.p. injection of 2×106 tumor cells were significantly reduced by TS‐1 in a dose‐dependent manner (15–20 mg/kg), when it was orally administered from day 1 post‐injection for 4 weeks (early administration). No such inhibition was evident after injection of 1×107 tumor cells. When 2×106 tumor cells given injection, the ascites‐free period in TS‐1‐treated mice was significantly longer than in their untreated counterparts. Survival of TS‐1‐treated mice (5/15) was also significantly higher than the zero rate in controls (0/15), with 4 out of 5 surviving mice being free from peritoneal metastasis and the exception having only a few dormant metastases. In contrast, when TS‐1 was administered starting from day 7 post‐injection for 4 weeks (late administration), the survival and ascites‐free period of the TS‐1‐treated mice were not significantly influenced. The results indicate that the Chemosensitivity of peritoneal metastases to TS‐1 is dependent on the number of i.p. tumor cells and the timing of drug administration. Peritoneal micrometastases at an early stage are most susceptible and can be effectively eliminated by oral administration of an anti‐cancer agent, which leads to the longer survival and better quality of life (QOL) of the mice. (Cancer Sci 2003; 94: 112–118)

A feasibility study of postoperative chemotherapy with S-1 and cisplatin (CDDP) for gastric carcinoma (CCOG0703)

BackgroundThe outcome of stage III gastric cancer patients treated by D2 dissection followed by adjuvant chemotherapy with S-1 remains unsatisfactory. Moreover, some patients with a preoperative diagnosis of stage II/III turn out to be stage IV after surgical exploration, and a standard postoperative treatment for this population has not been established.MethodsA feasibility study of postoperative S-1/cisplatin (CDDP) was performed with patients who underwent gastrectomy for what turned out to be a stage IV gastric cancer. The primary endpoint of the trial was the relative dose intensity during five courses of S-1/CDDP. Several criteria to skip, postpone, or reduce the dose had been predetermined.ResultsBetween 2007 and 2009, 31 patients were accrued, including 19 patients who were positive for peritoneal washing cytology, 6 with peritoneal seeding, 5 with metastasis to the paraaortic nodes, and 4 with other distant metastases. Only 7 patients completed five cycles as planned (median, two cycles). The median relative dose intensities of S-1 and CDDP were 37% and 40%, respectively. Causes of treatment failure were failure to fulfill criteria for starting a new course within 5 weeks of the last administration of S-1 in 7, patient refusal in 6, disease recurrence/progression in 4, need to reduce dose by two levels in 4, and two successive skips of CDDP in 3 patients. The median progression-free survival time of all patients was 363 days.ConclusionsAlthough promising in the neoadjuvant and advanced/metastatic setting, S-1/CDDP is too toxic as a postgastrectomy treatment for Japanese patients.