Micrometastases in the cervical lymph nodes in esophageal squamous cell carcinoma

Few studies have investigated the presence of lymph node micrometastases (MM) in the cervical region of patients with esophageal squamous cell cancer. The present study examines the presence of cervical MM and attempts to determine a way to predict the occurrence and site of such micrometastases. A total of 2203 cervical lymph nodes and 118 mediastinal recurrent nerve nodes obtained from 86 patients with esophageal carcinoma were examined immunohistochemically using cytokeratins. Cervical lymph nodes and mediastinal recurrent nerve nodes metastases were detected histologically in 33 and 41 of the 86 patients respectively. Cervical lymph node and mediastinal recurrent nerve node MM were immunohistochemically detected in 16 (18.6%) and 6 (7.0%) patients respectively. Of these 16 patients with cervical MM, seven were found to have lymph node metastases in different cervical regions, whereas cervical MM only were detected in nine patients. Among the former group of patients, five were diagnosed by ultrasound examination as having cervical lymph node metastases. Mediastinal recurrent nerve node metastases and MM correlated with the presence of cervical MM in all but one patient. Cervical lymph node metastasis, including micrometastasis, can be predicted by preoperative ultrasonography and the routine histologic examination of mediastinal recurrent nerve nodes.

Bax and Bcl-X(L) expression are not related to prognosis in patients with advanced esophageal squamous cell carcinoma

Bax and Bcl-X(L) genes play an important role in the apoptotic pathway. These expressions were immunohistochemically investigated in 111 patients with advanced esophageal squamous cell carcinoma. The positive rates of p53, Bax, and Bcl-X(L) were 42.3, 38.7, and 46.8%, respectively. The expression of both Bax and Bcl-X(L) was not related to clinicopathological findings, including survival. Neither Bax nor Bcl-X(L) expression correlated with p53 overexpression. Five-year survival rate did not differ according to the co-expression pattern of Bax and Bcl-X(L). In 44 patients who underwent chemotherapy and/or radiation therapy after surgery, Bax and Bcl-X(L) expression was not related to patients' survival. Multiple apoptotic pathways may be associated with advanced esophageal squamous cell carcinoma.

Role of thymidine phosphorylase in Fas-induced apoptosis

Thymidine phosphorylase (TP) has chemotactic and angiogenic activity in vitro, and it promotes tumor growth and inhibits apoptosis in vivo. It plays a key role in the invasiveness and metastasis of TP-expressing solid tumors. KB/TP cells transfected with a TP cDNA have been shown to be resistant to hypoxia-induced apoptosis, suggesting that TP has effects on tumor growth and cell death independent of its effects on angiogenesis. However, the mechanisms of cell death inhibition by TP are unknown. In the present study, we demonstrate that caspase-8 is cleaved in control transfectant KB cells early on during Fas-induced apoptosis. Caspase-8 activation leads to the loss of mitochondrial membrane potential, followed by the release of cytochrome c, the activation of caspase-3, and apoptosis. In contrast, Fas-induced caspase-8 cleavage is inhibited in KB/TP cells, which lead to inhibition of the downstream apoptotic cascade and inhibition of apoptosis. These findings indicate that TP plays an important role in intracellular apoptotic signal transduction in the Fas-induced apoptotic pathway. Therefore, inhibition of TP may suppress the progression of TP-overexpressing solid tumors by inducing apoptosis.

Intrahepatic cholangiocarcinoma arising 10 years after the excision of congenital extrahepatic biliary dilation

A 52-year-old woman was found to have a liver tumor during treatment for a liver abscess. The tumor was diagnosed as intrahepatic cholangiocarcinoma by closer examinations, including a percutaneous needle biopsy. Ten years previously, she had undergone excision of a choledochal cyst, with reconstruction by Roux-en-Y hepaticojejunostomy, as treatment for Todani's type Ia congenital biliary dilation, which had been confined only to the extrahepatic bile duct. The significant association between congenital biliary dilation and hepatobiliary malignancies is well known. Some patients have been reported to develop biliary cancer long after the excision of the entire extrahepatic bile duct and hepaticoenterostomy. However, in these patients, the development mostly took place in the remnant choledochal cyst, the anastomotic site, or in the dilated intrahepatic bile duct of Todani's type IV-A congenital biliary dilation. The development of intrahepatic cholangiocarcinoma after operation has not been reported previously in a patient with Todani's type I congenital biliary dilation. This case suggests that the entire biliary tree may have a high risk of field cancerization, even in extrahepatic congenital biliary dilation.

Magnetic compression anastomosis for benign obstruction of the common bile duct

Advances in interventional radiology have made possible magnetic compression anastomosis between the bile duct and the small intestine as a novel treatment. A 70-year-old man who had undergone subtotal gastrectomy for gastric cancer 2 years previously experienced recurring cholangitis with high fever and jaundice. Diagnostic evaluation subsequently demonstrated complete obstruction of the common bile duct which was attributed to recurrent cholangitis. A parent magnet was placed endoscopically into the afferent loop of the duodenum through the gastrojejunostomy with Billroth II reconstruction. The daughter magnet attached to a guide wire was placed in the obstructed common bile duct through a percutaneous transhepatic cholangiographic drainage tube. Two magnets were immediately attracted towards each other transmurally, and anastomosis was established on day 32 after the procedure. This novel method of magnetic compression anastomosis has the advantages of noninvasiveness and simplicity, as well as being a well-tolerated procedure for indications such as biliary obstruction.

Number of lymph node metastases determined by presurgical ultrasound and endoscopic ultrasound is related to prognosis in patients with esophageal carcinoma

OBJECTIVE

To analyze the impact on prognosis of the number of lymph node metastases detected by ultrasound and endoscopic ultrasound in patients with esophageal carcinoma.

SUMMARY BACKGROUND DATA

Ultrasound and endoscopic ultrasound are useful for diagnosing tumor depth and lymph node metastasis in patients with esophageal carcinoma. However, the clinical significance of the number of lymph node metastases before surgery has not been elucidated.

METHODS

The authors evaluated lymph node metastases using preoperative ultrasound and endoscopic ultrasound in 329 consecutive patients who underwent esophagectomy with lymphadenectomy. TNM classification and one-to-one comparison of lymph node metastasis was performed between the preoperative and histologic diagnosis. The number of lymph node metastases was subdivided into four groups: zero, one to three, four to seven, and eight or more.

RESULTS

The accuracy of preoperative ultrasound and endoscopic ultrasound diagnosis exceeded 70% in each category of TNM classification. The incidence of lymph node metastasis determined by preoperative and histologic diagnosis was 69.0% (234/339) and 59.3% (201/339), respectively. The correlation between preoperative and histologic diagnosis was significant (P <.0001). According to the subdivision of number of lymph node metastases, the accuracy rates associated with nodal involvement of zero, one to three, four to seven, and eight or more were 83.8%, 59.7%, 43.3%, and 96.0%, respectively. The clinical outcome between ultrasound and endoscopic ultrasound diagnosis and histologic diagnosis in stage grouping was almost similar. The 5-year survival rates of patients with zero, one to three, four to seven, and eight or more lymph node metastases determined by ultrasound and endoscopic ultrasound were 53.3%, 33.8% 17.0%, and 0%, respectively. The differences among groups were statistically significant. The survival curves associated with preoperative and histologic diagnosis were similar.

CONCLUSIONS

Not only the stage grouping of TNM classification but also the number of lymph node metastases determined by ultrasound and endoscopic ultrasound before surgery may be useful for predicting prognosis in patients with esophageal carcinoma.

Human T-lymphotropic retrovirus type-1 in Thailand

Seroprevalence of antibodies to human T-lymphotropic virus type-1 (HTLV-1) was surveyed among the Thai population by the particle agglutination test and Western blotting test. None of a total of 727 individuals from seven ethnic groups were positive for the specific antibody to HTLV-1. Among hospital based 3,427 subjects in Southern Thailand, one patient with a brain tumor showed positivity in the Western blotting test, however, HTLV-1 proviral genome was not identified by PCR. The present data suggest that HTLV-1 is not endemic in the Thai population and that HTLV-1 is not a major public health problem in Thailand because HTLV-1 rarely causes its associated diseases.

Epstein-Barr virus involvement is mainly restricted to lymphoepithelial type of gastric carcinoma among various epithelial neoplasms

To demonstrate the association of Epstein-Barr virus (EBV) with primary epithelial neoplasms in the south part of Kyushu, Japan, 761 carcinomas consisting of 75 lung, 61 breast, 107 esophagus, 102 colon, 58 pancreas, 45 thyroid, and 313 gastric cancers were examined by EBER-1 in situ hybridization. EBER-1 was detected in 23 cases (7.3%) out of 313 gastric carcinomas, while none of the other carcinomas was positive for EBER-1. Twenty-eight (9.4%) out of 313 gastric carcinomas were differentiated poorly to moderately carcinomas with prominent lymphoid cell infiltration, similar to so-called lymphoepithelioma-like carcinoma, and 19 cases (67.9%) were positive for EBER-1. Although two (2.6%) and 11(10.3%) out of 75 lung and 107 esophagus carcinomas were so-called lymphoepithelioma-like carcinomas, respectively, but EBER-1 was not detected in other epithelial neoplasms that originated from the lung, esophagus, breast, colon, pancreas, and thyroid in the south of Kyushu, Japan. As a result, EBV was associated with only some gastric carcinomas but not with other epithelial neoplasms originating from the lung, esophagus, breast, colon, pancreas, and thyroid in southern Japan.

Clinical significance and prognostic value of apoptosis related proteins in superficial esophageal squamous cell carcinoma

BACKGROUND

The purpose of the present study was to examine the expression of cell cycle regulators [p53, p21WAF1/CIP1 (p21), and Rb] and apoptosis related proteins Bax and Bcl-X(L) and to evaluate the relationship between their expressions and clinicopathological findings in patients with superficial squamous cell carcinomas of the esophagus.

METHODS

We immunohistochemically investigated the expression of p53, p21, Rb, Bax, and Bcl-X(L) in 79 patients with superficial esophageal carcinoma.

RESULTS

p21 overexpression was found in mucosal carcinoma (P = 0.05) and a high Bcl-X(L) score was observed for submucosal carcinoma (P = 0.03). The patients with high Bcl-X(L) score had more frequent lymphatic invasion and lymph node metastasis than did those with low Bcl-X(L) score (P < 0.05). Univariate analysis revealed significantly shorter survival in patients with high Bcl-X(L) expression than in those with low Bcl-X(L) expression, but Bcl-X(L) expression was not identified as an independent prognostic factor by multivariate analysis.

CONCLUSIONS

Because Bcl-X(L) expression correlated well with depth of tumor invasion, lymphatic invasion, and lymph node metastasis, examination of Bcl-X(L) expression will help to estimate the properties in superficial squamous cell carcinoma of the esophagus.

Detection and prediction of micrometastasis in the lymph nodes of patients with pN0 gastric cancer

BACKGROUND

The clinicopathologic significance of micrometastasis (MM) and tumor cell microinvolvement (TCM) in regional lymph nodes as identified by immunohistochemical staining for cytokeratin expression was evaluated in patients with node-negative gastric cancer.

METHODS

MM was defined as tumor cells with stromal reaction, and TCM was defined as individual tumor cells without stromal reaction. We investigated 1761 lymph nodes obtained from 67 gastric cancer patients whose diagnosis showed no lymph node metastasis by routine histological examination. The depth of tumor invasion was T1 (submucosa) in 33 patients and T2 (muscularis propria and subserosa) in 34 patients. The lymph nodes were examined immunohistochemically for the presence of tumor cells using anti-cytokeratin AE1/AE3 monoclonal antibody. Both the biopsy tumor specimens obtained prior to surgery and the resected primary tumors were immunostained with E-cadherin (E-cad) monoclonal antibody.

RESULTS

Thirty (1.5%) of the 1761 lymph nodes showed MM and/or TCM. MM with or without TCM was found in 10 patients, and TCM alone was found in 4 patients; 6 (18.2%) of the 33 patients with T1 tumor and 8 (23.5%) of the 34 patients with T2 tumor had occult lymph node metastasis. The 5-year survival rate was worse among those with MM with or without TCM, than among those without MM. Nearly all of the patients with MM and/or TCM had reduced or negative E-cad expression in the primary tumor.

CONCLUSIONS

We demonstrated that the incidence of MM and/or TCM in the lymph nodes of patients with gastric cancer is quite high, and that such metastasis is associated with the prognosis of patients with pN0. Examination of E-cad expression in biopsy tumor specimens may be useful for predicting MM and/or TCM.

Allelotype analysis of gallbladder carcinoma associated with anomalous junction of pancreaticobiliary duct

Anomalous junction of pancreaticobiliary duct (AJPBD) patients has an increased risk of gallbladder and bile duct carcinomas. However, the relevance of carcinoma with AJPBD is not fully clarified. We performed analysis of loss of heterozygosity (LOH) at p53 locus and immunohistochemistry of p53 and K-ras gene mutation in five cases of gallbladder carcinoma associated with AJPBD. LOH of p53 locus and overexpression of p53 were detected in two out of five (40%) and five out of five (100%), respectively, in the present study. K-ras gene mutation at codon 12 and 13 was not detected (0%, 0/5). These results suggest that aberrations of p53 are involved in carcinogenesis of gallbladder carcinoma associated with AJPBD. Next, in order to find the genetic events besides K-ras mutation and overexpression of mutant p53 in this disease, LOH analysis was performed using 72 microsatellite markers. High frequency of allelic loss (> 50%) was found on 2p (81.8%), 4p (50%), 4q (50%), 8q (60%), 9q (50%), 10p (50%), 14p (60%), 14q (50%), 16p (60%), 19p (50%), 21p (50%) and Xp (66.6%). The highest deletion regions on chromosome 2p24 (3/3, 100%), 14q22 (3/4, 75%) and 21q22 (3/4, 75%) were found. The present study suggests that gallbladder carcinoma associated with AJPBD has high frequent allelic loss and has two new regions which may harbor putative tumor suppressor genes.

Hand-assisted laparoscopic distal pancreatectomy with minilaparotomy for distal pancreatic cystadenoma

Two patients with cystic tumors of the pancreas treated by laparoscopic distal pancreatectomy are presented. The first patient was a 34-year-old woman with a 6-cm cystadenoma of the tail of the pancreas treated with a complete laparoscopic distal pancreatectomy. After mobilization of the distal pancreas and spleen, the pancreas was transected proximally together with the splenic artery and vein using an endoscopic linear stapler. The second patient was a 71-year-old woman with a 6-cm cystadenoma of the body of the pancreas, treated by hand-assisted laparoscopic distal pancreatectomy with minilaparotomy because the tumor was adjacent to the portal vein and celiac axis. Using an upper median minilaparotomy, dissection of the gastrocolic ligament, division of the splenic artery, and transection and closure of the pancreas were performed. Division of the splenic vein and mobilization of the distal pancreas and spleen were performed via a hand-assisted laparoscopic approach. There were no postoperative complications (such as pancreatic fistulas) in either patient, and the postoperative courses were uneventful. The patients returned to normal activity within 1 week after the operation. Complete laparoscopic and hand-assisted laparoscopic distal pancreatectomy are preferable to conventional open surgery for benign tumors of the pancreas because of their less-invasive nature. Additionally, in tumors of the body of the pancreas, hand-assisted laparoscopic distal pancreatectomy might have the advantages of laparotomy and laparoscopy in terms of handling the splenic artery and vein just below the minilaparotomy site, suggesting an easier and safer procedure than complete laparoscopic distal pancreatectomy. Therefore, hand-assisted laparoscopic distal pancreatectomy can be recommended as a useful alternative to complete laparoscopic distal pancreatectomy for selected patients with benign tumors of the body and tail of the pancreas.

Detection and prediction of micrometastasis in the lymph nodes of patients with pN0 gastric cancer

BACKGROUND

The clinicopathologic significance of micrometastasis (MM) and tumor cell microinvolvement (TCM) in regional lymph nodes as identified by immunohistochemical staining for cytokeratin expression was evaluated in patients with node-negative gastric cancer.

METHODS

MM was defined as tumor cells with stromal reaction, and TCM was defined as individual tumor cells without stromal reaction. We investigated 1761 lymph nodes obtained from 67 gastric cancer patients whose diagnosis showed no lymph node metastasis by routine histological examination. The depth of tumor invasion was T1 (submucosa) in 33 patients and T2 (muscularis propria and subserosa) in 34 patients. The lymph nodes were examined immunohistochemically for the presence of tumor cells using anti-cytokeratin AE1/AE3 monoclonal antibody. Both the biopsy tumor specimens obtained prior to surgery and the resected primary tumors were immunostained with E-cadherin (E-cad) monoclonal antibody.

RESULTS

Thirty (1.5%) of the 1761 lymph nodes showed MM and/or TCM. MM with or without TCM was found in 10 patients, and TCM alone was found in 4 patients; 6 (18.2%) of the 33 patients with T1 tumor and 8 (23.5%) of the 34 patients with T2 tumor had occult lymph node metastasis. The 5-year survival rate was worse among those with MM with or without TCM, than among those without MM. Nearly all of the patients with MM and/or TCM had reduced or negative E-cad expression in the primary tumor.

CONCLUSIONS

We demonstrated that the incidence of MM and/or TCM in the lymph nodes of patients with gastric cancer is quite high, and that such metastasis is associated with the prognosis of patients with pN0. Examination of E-cad expression in biopsy tumor specimens may be useful for predicting MM and/or TCM.

Preserved Smad4 expression in the transforming growth factor beta signaling pathway is a favorable prognostic factor in patients with advanced gastric cancer

The signals of the transforming growth factor beta (TGF-beta) superfamily are conveyed through cell surface serine/threonine kinase receptors to the intracellular mediators known as Smads. Activation of Smads causes their translocation from the cytoplasm to the nucleus, where they function to control gene expression. The present study analyzed the expression of Smad4 and TGF-beta1 to determine their prognostic significance in advanced gastric cancer. Of 249 cases of advanced gastric cancer, 41 had invaded the muscular layer, 114 had invaded the subserosal layer, and 94 had invaded the serosa. Anti-Smad4 and TGF-beta1 antibodies were used for immunohistochemical staining. Reduced expression of Smad4 was 75.1%, whereas positive expression of TGF-beta1 was 39.6% in gastric cancer. Smad4 expression was related to the depth of tumor invasion (P < 0.05), and TGF-beta1 expression correlated with tumor gross type (P < 0.05). Postoperative survival analysis indicated that patients who had a tumor with reduced Smad4 expression had a poorer clinical outcome than those with preserved expression (P < 0.05). Furthermore, in patients with TGF-beta1-positive tumors, survival rate was significantly better in patients with preserved Smad4 expression than in those with reduced Smad4 expression (P < 0.05). According to multivariate analysis, Smad4 expression acted as an independent prognostic factor. Smad4 expression, particularly in the TGF-beta pathway, is an effective predictor of outcome for patients with advanced gastric cancer.

Surgical maneuvers enhance molecular detection of circulating tumor cells during gastric cancer surgery

OBJECTIVE

To evaluate the relation between the presence of cancer cells in blood according to the time course during a surgical procedure and liver metastases in patients with gastric cancer.

SUMMARY BACKGROUND DATA

Several studies have reported on the detection of circulating cancer cells in blood by reverse transcriptase-polymerase chain reaction (RT-PCR). However, few reports have examined the relation between molecular detection of circulating cancer cells according to the time course during a surgical procedure and blood-borne metastases.

METHODS

Blood samples from 57 patients with gastric cancer were obtained from the portal vein, peripheral artery, and superior vena cava before and after tumor dissection. After total RNA was extracted from each blood sample, carcinoembryonic antigen (CEA)-specific RT-PCR was performed.

RESULTS

CEA-mRNA was detected in the blood of 21 (36.8%) of the 57 patients. CEA-mRNA was not detected in the blood obtained from 15 healthy volunteers and 15 patients with benign disease. The positive rate increased in proportion to the depth of tumor. The incidence of positive CEA-mRNA did not differ among the various sites of blood sampling. The appearance of circulating cancer cells was related to the surgical maneuver. A significant relation was found between the detection of CEA-mRNA and blood-borne metastases.

CONCLUSIONS

A high incidence of positive CEA-mRNA was found in the blood during gastric cancer surgery. Surgical maneuvers are a possible cause of hematogenous metastasis. The authors found that patients with positive CEA-mRNA had a high risk of blood-borne metastasis even after curative resection.

Structure, expression and chromosome mapping of MLZE, a novel gene which is preferentially expressed in metastatic melanoma cells

We isolated a novel gene, termed MLZE, from a B16-BL6 cDNA library after subtraction of B16-F10 mRNA. Expression levels of mouse MLZE (mMLZE) increased in accordance with metastatic ability of B16 melanoma sublines. Human homolog of mMlze (hMlze) contained one leucine zipper structure and two potential nuclear localizing signals. Northern blot analysis of multiple human tissues showed that hMLZE was expressed primarily in trachea and spleen. We mapped the hMLZE gene (by fluorescence in situ hybridization) to 8q24.1 - 2, which contains the c-myc gene and is often amplified in malignant melanoma. Immunohistochemistry revealed that the number of hMlze-positive cases was significantly larger in Clark levels III, IV and V melanomas (6 / 11 = 55%) than in Clark levels I and II melanomas (2 / 15 = 13%). In two cases of hMlze-positive melanomas, the strength of hMlze staining increased substantially in the deep component of the tumor. Considering that melanomas above Clark level II are more metastatic than those below Clark level III, these findings suggested that MLZE is one of the genes whose expression is upregulated during the course of acquisition of metastatic potential in melanoma cells.

Clinical importance of preoperative carcinoembryonic antigen and carbohydrate antigen 19-9 levels in gastric cancer

Although serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 are commonly measured before surgery for gastric carcinoma, this clinical significance is not fully understood. We evaluated a total of 549 patients with gastric cancer who underwent gastrectomy. Levels of CEA and CA19-9 were measured preoperatively in all patients. We retrospectively analyzed correlations between CEA or CA19-9 and clinicopathologic features, and estimated the prognostic utility of the tumor markers by analyzing clinicopathologic characteristics of the carcinoma as a function of seropositivity or negativity of the antigens in combination or by raising the levels. The positivity rates of CEA (> or =5 ng/mL) and CA19-9 (> or =37 U/mL) were 19.5% and 18%, respectively. Serum CEA and CA19-9 positivity significantly correlated with depth of invasion, hepatic metastasis, and curativity. Forty-nine patients positive for both CEA and CA19-9 had significantly higher frequencies of lymph node metastasis, deeper invasion by the tumor, lower rates of curative resection (p < 0.01), and higher rates of hepatic metastasis (p < 0.05) than 377 patients with normal levels of CEA and CA19-9. Surgical outcomes of patients who were CEA- and CA19-9-positive were poorer than those of patients with normal CEA and CA19-9 levels (p < 0.01). Significant correlation was found between serum CEA and CA19-9 level (p < 0.001, r = 0.24). Doubling the threshold level of serum positivity to 10 ng/mL (CEA) and 74 U/mL (CA19-9) improved the prognostic value of these factors. However, multivariate analysis using Cox's hazards model revealed that only CEA positivity using the doubled threshold value (10 ng/mL) (p = 0.04, hazard ratio = 1.7), nodal involvement (p = 0.01, hazard ratio = 1.9), and depth of invasion (p = 0.02 hazard ratio = 1.5) significantly predicted prognosis. Carcinoembryonic antigen positivity using the doubled threshold level (10 ng/mL) was an important prognostic factor in patients with gastric cancer.

Two cases of severe bronchopneumonia due to influenza A (H3N2) virus: detection of influenza virus gene using reverse transcription polymerase chain reaction

We report two cases of severe bronchopneumonia due to influenza A (H3N2) virus. The severity of the disease necessitated initiation of empiric therapy based on the present illness and clinical data on admission. Both patients were improved by artificial ventilation with positive end-expiratory pressures and administration of broad spectrum antibiotics and corticosteroids before confirming the diagnosis of viral bronchopneumonia using viral culture and serological tests. Within 24 hours, influenza A (H3N2) virus was identified by amplification of the pathogen genes by reverse transcription polymerase chain reaction (RT-PCR) using the stored bronchoalveolar lavage (BAL) fluids of both cases. This suggests that a combination of detection methods of pathogens using RT-PCR and BAL fluid will facilitate determination of rational treatment aimed at influenza A virus.

N-acetyl cysteine inhibits cell cycle progression in pancreatic carcinoma cells

The antioxidant N-acetyl cysteine (NAC) is a precursor of intracellular glutathione (GSH) and is also a well known as one of the chemopreventive agents which act through a variety of cellular mechanisms. We examined the effects of NAC on cell cycle progression in the pancreatic carcinoma cell lines, SW1990 and JHP1. Cells were incubated with or without NAC. Cell cycle distribution was analyzed by flow cytometry and immunoblotting. NAC suppressed cell proliferation in a concentration-dependent manner, whereas NAC increased intracellular glutathione content significantly in a dose-dependent manner. The percentage of cells in the G1 phase after treatment with NAC was significantly higher than the percentage seen for control cells. Cyclin D1 expression of carcinoma cells treated with NAC decreased remarkably compared with cells without NAC treatment. Thus, the antiproliferative effect of NAC by prolongation of the G1 phase in human pancreatic carcinoma cells shows its possible utility as an antitumor agent.