小分子干扰RNA沉默肝癌细胞CDK2基因对RB、CyclinE、E2F1基因表达的影响

【目的】观察小分子干扰RNA(siRNA)沉默细胞周期素依赖性蛋白激酶(CDK2)基因后,细胞周期相关基因RB、CyclinE、E2F1在肝癌细胞SMMC7721中mRNA的表达。【方法】将前期研究中已构建成功并筛选出的最有效干扰抑制CDK2基因的siRNA序列片段,采用Lipofectamine TM2000脂质体转染法转染肝癌细胞株SMMC7721后分6组:重组质粒组190、重组质粒组191、SMMC7721肝癌组、转染试剂组、阴性对照组、空质粒组。采用实时荧光定量PCR法检测RB、CyclinE、E2F1 mRNA水平。【结果】CDK2的siRNA转染SMMC7721细胞后,RB基因mRNA表达上调,CyclinE、E2F1基因mRNA表达下调。【结论】抑制CDK2基因的表达能使肝癌细胞SMMC7721中RB基因mRNA表达上调,CyclinE、E2F1基因mRNA表达下调,提示肝癌细胞中RB、CyclinE、E2F1基因的表达与CDK2基因的表达具有明显的相关性。

SOD模型化合物对离体肝癌细胞DNA的损伤作用

目的 :探讨超氧化物歧化酶模型化合物 (modelsofsuperoxidedismutase ,MSOD)对离体人肝癌细胞毒作用。方法 :采用离体培养的人肝癌细胞SSMC 772 1细胞株 ,常规方法接种入 2 4孔板 ,加入SOD模型化合物 ,以彗星实验为终点效应 ,检测其对肿瘤细胞的影响。结果 :通过彗星试验检测 ,各剂量组所起的肝癌细胞DNA损伤或DNA断裂的程度呈明显的剂量效应关系。结论 :这种模型化合物对离体培养的肝癌细胞有明显细胞毒作用。

骨髓转移癌98例细胞形态学分析

目的 探讨骨髓转移癌的细胞形态学特点 ,及骨髓内造血细胞与肿瘤恶性程度及癌细胞类型的关系。方法 瑞特染色用日本产的显微镜对 98例患者的骨髓穿刺涂片进行油镜检查。结果 通过对 98例骨髓转移癌骨髓象分析 ,主要以胃癌、食道癌、肺癌、乳腺癌骨髓内转移为主 ,占全部转移癌的 6 8.35 %。结论 癌细胞的类型恶性程度与骨髓增生度有关。

抗癌防移片抑制4T1乳腺癌血管生成的机制研究

【目的】探讨抗癌防移片抑制4T1乳腺癌血管生成的机理。【方法】选用BALB/c小鼠建立4T1乳腺癌模型,随机分成空白对照组、模型组、环磷酰胺(CTX,剂量为0.04 g·kg-1·d-1)组和抗癌防移片组(剂量为5.2 g·kg-1·d-1),分别给予药物或生理盐水,给药4周后处死小鼠,测量剥离瘤质量,计算剥离瘤质量抑制率以及计数肺转移结节数,并通过免疫组织化学染色法测定肿瘤微血管数与血管内皮细胞生长因子(vascular endothelial growth factor,VEGF)表达。【结果】与模型组比较,抗癌防移片组剥离瘤质量显著减轻(P<0.05),肺转移结节数目显著减少(P<0.05),且剥离瘤微血管数与VEGF表达有降低趋势。【结论】抗癌防移片可能通过下调VEGF、抑制肿瘤微血管生成从而抑制4T1小鼠乳腺癌生长与转移。

Expression of Angiopoietin-2 and Vascular Endothelial Growth Factor in Oral Squamous Cell Carcinoma and Its Significance

Objective： To investigate the expression of angiopoietin-2 （Ang-2） and vascular endothelialcell growth factor （VEGF） in oral squamous cell carcinoma （OSCC） and their correlations with clinicopathologic parameters, angiogenesis and vessel maturation of OSCC. Methods： The expression of Ang-2 and VEGF was detected in 41 speciments of human OSCC, 30 adjacent noncancerous oral tissues and 10 specimens of normal oral mucosa by conventional immumohistochemistry. Microvessel density （MVD） and vessel maturation index （VMI） were also assessed by double-labelling immumohistochemistry staining against CD34, a marker of pan-endothelial cells, and that against alpha-smooth muscle actin （α-SMA）, a marker of mural cells （pericytes/smooth muscle cells）. Results： The positive expression rate of Ang-2 and VEGF in 41 OSCC tissues was 51.22% and 63.42%, respectively. The expression of Ang-2 and VEGF was significantly higher in OSCC than in adjacent noncancerous oral tissues （all P〈0.05） and normal oral mucosa （all P〈0.05）. In the clinicopathologic parameters, the Ang-2 expression was closely correlated with tumor lymph node metastasis （P〈0.01） and the VEGF expression was correlated with tumor differentiated degree （P〈0.05）, but there was no significant correlation among the Ang-2 and VEGF expression and patients＇ sex, age and TNM stages （all P〉0.05）. The MVD of OSCC positive for both Ang-2 and VEGF was significantly higher than that of OSCC negative for both Ang-2 and VEGF （P〈0.05）. The VMI of OSCC positive for Ang-2 was significantly lower than that of OSCC negative for Ang-2 （P〈0.05）. When Ang-2 expression was combined with the staus of VEGF expression, MVD of OSCC positive for both Ang-2 and VEGF was the highest （51.08±2.99） as compared with that of other status in patient with OSCC （all P〈0.05）. Conclusion： The overexpression of Ang-2 and VEGF may play a crucial role in the development of OSCC. They are closely associated with angiogenesis and vessel maturation of tumor.

Histopathological study of hepatocellular carcinoma after transcatheter hepatic arterial embolization

AIMS To study the histopathological changes in hepatocellular carcinoma (HCC) after transcatheter arterial embolization (TAE). METHODS Histopathological analysis was made in 39 cases of liver neoplasms after TAE and 11 cases of liver neoplasms after digital selective angiography (DSA), including pathological type, histological grade, necrotic degree, capsule, times of treatment, injured vessel and lymphocyte infiltration. RESULTS Six cases with 100% necrosis, 14 cases with 30% 95% necrosis, 19 cases with 0% 5% necrosis after TAE and 11 cases without necrosis after DSA were found histologically. The necrosis was related to the pathological type, capsule, injured vessels, but not to the histological grade, time of treatment and lymphocyte infiltration of the liver neoplasms. CONCLUSIONS TAE is an effective therapy for the late stage HCC. The encapsulated HCC is a preferable indicator for TAE.

Role of sex steroid receptors in pathobiology of hepatocellular carcinoma

The striking gender disparity observed in the incidence of hepatocellutar carcinoma （HCC） suggests an important role of sex hormones in HCC pathogenesis. Though the studies began as early as in 1980s, the precise role of sex hormones and the significance of their receptors in HCC still remain poorly understood and perhaps contribute to current controversies about the potential use of hormonal therapy in HCC. A comprehensive review of the existing literature revealed several shortcomings associated with the studies on estrogen receptor （ER） and androgen receptor （AR） in normal liver and HCC. These shortcomings include the use of less sensitive receptor ligand binding assays and immunohistochemistry studies for ERα alone until 1996 when ERβ isoform was identified. The animal models of HCC utilized for studies were primarily based on chemical-induced hepatocarcinogenesis with less similarity to virus-induced HCC pathogenesis. However, recent in vitro studies in hepatoma cells provide newer insights for hormonal regulation of key cellular processes including interaction of ER and AR with viral proteins. In light of the above facts, there is an urgent need for a detailed investigation of sex hormones and their receptors in normal liver and HCC. In this review, we systematically present the information currently available on androgens, estrogens and their receptors in normal liver and HCC obtained from in vitro, in vivo experimental models and clinical studies. This information will direct future basic and clinical research to bridge the gap in knowledge to explore the therapeutic potential of hormonal therapy in HCC.

Nuclear and mitochondrial DNA microsatellite instability in hepatocellular carcinoma in Chinese

AIM：To study the nuclear microsatellite instability (nMSI) at BAT26 and mitochondral microsalellite instability (mtMSI) in the occurrence and development of hepatocellular carcinoma and the relationship between nMSI and mtMSI.METHODS: nMSI was observed with PCR and mtMSI with PCR-SSCP in 52 cases of hepatocellular carcinoma.RESULTS:mtMSI was detected in 11 out of the 52 cases of hepatocellular carcinoma (21.2%). Among the 11 cases of hepatocellular carcinoma with mtMSI, 7 occured in one locus and 4 in 2 loci. The frequency of mtMSI in the 52 cases of hepatocellular carcinoma showed no correlation to sex, age,infection of hepatitis B, liver cirrhosis as well as positive AFP of the patients (P>0.05). In addition, nMSI was detected in 3 out of 52 cases of hepatocellular carcinoma (5.8%) and there was no correlation of the incidence of mtMSI to that of nMSI (P>0.05).CONCLUSION:mtMSI may be involved in the coccurrence and development of hepatocellular carcinoma and it is independent of nMSI.

A case of long survival in poorly differentiated small cell carcinoma of the pancreas

Small cell carcinoma (SCC) of the pancreas is rare. It has similar histological features to pulmonary small cell carcinoma and is equally aggressive. Most patients with SCC in the pancreas reported in case studies died within 1 year after diagnosis. We present a case of unusually long-term survival after surgery and combined chemotherapy for SCC of the pancreas. A 62-year-old woman presented with epigastric pain and jaundice. Computed tomography revealed dilated common bile duct caused by external compression of the mass in the pancreatic head. Exploratory laparotomy and pancreaticoduodenectomy (PPPD) was performed with histopathological analysis confirming a primary small cell carcinoma of the pancreas. After an uneventful postoperative recovery, the patient was treated with 6 cycles of combined chemotherapy consisting of cisplantin and ectoposide. During the follow-up, there was no evidence of recurrence and the patient has remained in a good health condition for 36 mo since the diagnosis.

Gender difference in clinicopathologic features and survival of patients with hepatocellular carcinoma

AIM: To determine the influence of gender on the clinicopathologic characteristics and survival of patients with hepatocellular carcinoma (HCC). METHODS: A retrospective analysis of medical records was performed in 299 patients with HCC and their clinicopathologic features and survival were compared in relation to gender. RESULTS: There were 260 male (87%) and 39 female patients (13%),with a male-to-female ratio of 6.7:1.Female patients had lower mean serum bilirubin levels (P=0.03), lower proportion of alcohol abuse (P=0.002),smaller mean tumor size (P=0.02),more frequent nodular type but less frequent massive and diffuse types of HCC (P=0.01),were less advanced in Okuda's staging (P=0.04),and less frequently associated with venous invasion (P=0.03).The median survivals in females (14 too) were significantly longer than that of male patients (4 mo) (P=0.004,log-rank test). Multivariate analysis demonstrated that high serum alpha- fetoprotein levels,venous invasion,extrahepatic metastasis and lack of therapy were independent factors related to unfavorable prognosis.However,gender did not constitute a predictive variable associated with patient survival. CONCLUSION: Female patients tend to have higher survival rates than males.These differences were probably due to more favorable pathologic features of HCC at initial diagnosis and greater likelihood to undergo curative therapy in female patients.

Extremely well-differentiated adenocarcinoma of the stomach: Clinicopathological and immunohistochemical features

AIM： Minimal deviation carcinoma of the uterine cervix, otherwise known as extremely well-differentiated adenocarcinoma （EWDA）, is characterized by its benign microscopic appearance in contrast to its aggressive behavior. In order to elucidate the clinicopathological features and biological behavior of the gastric counterpart of EWDA, we, using immunohistochemistry, analyzed nine lesions for the phenotypic expression, proliferative activity, and the expression of oncogene-associated products. METHODS： Clinicopathological features, including preoperative biopsy diagnosis, were reviewed. Using immunohitstochemistry, Ki-67 labeling index and expression of p53 and c-erbB-2 protein in the gastric lesions were detected.RESULT： Locations in the middle or upper third of the stomach and polypoid macroscopic features are characteristic of EWDA of the stomach. Although 4 of the 9 lesions showed only focal lymphatic or venous invasion, lymph node metastasis was not present and none of the patients died of the lesions （mean follow-up period, 56 too）. All 9 cases of EWDA could be classified into gastric phenotype （5 lesions） and intestinal phenotype （4 lesions）. The former resembled gastric foveolar epithelium, mucous neck cells or pyloric glands, but their papillary structures were frequently elongated and the tumor cellsand their nuclei were slightly larger and more hyperchromatic compared to normal epithelium. The latter resembled intestinal metaplasia with minimal nulcear atypia and irregular glands; two of these lesions demonstrated complete intestinal phenotype, while two demonstrated incomplete intestinal phenotype. Ki-67 labeling index was low and none of the cases revealed over-expression of p53 and c-erbB-2 protein. CONCLUSION： Unlike minimal deviation carcinoma of the cervix, these findings suggest that EWDA of the stomach is a lesion of low-grade malignancy. This favorable biological behavior is supported by the data of a low Ki-67 labeling index and a lack of p53 or c-erbB-2 protein over-expression. Because of its resemblance to normal gastric mucosa or mucosa with intestinal metaplasia, EWDA is often misdiagnosed. To prevent the misdiagnosis of such lesions, the clinical and pathologic characteristics should be taken into consideration.

Cryoablation Combined with TACE for Treating Large Hepatocellular Carcinoma： Tumor Load and Cellular Immunity

OBJECTIVE To study the effectiveness on the tumor load and cellular immune function of percutaneous cryoablation （argon-helium cryoablative system, AHCS） combined with transarterial chemoembolization （TACE） for treating large hepatocellular carcinomas （HCCs） with diameters over 10 ca. METHODS A total of 48 HCC patients were treated with AHCS after TACE. Tumor sizes ranged from 10 to 14 cm. All cases were a hypervascular type. There were 38 Child A cases and 10 Child B cases. Forty were AFP positive and 8 negative. The patients were randomized with therapy group consisting of 26 cases and the control group 22 cases. The therapy group received AHCS 4 weeks following TACE treatment. Reexamination included pathology, tumor markers, T-lymphocyte subgroup levels and computed tomography or MRI. The necrosis rate of the tumor load was calculated by Cavalieri＇s theory. EORTC QLQ-C30 was used in quality of life evaluation. RESULTS The average tumor-load reduction rate （necrosis rate） was 8.07% after TACE, and 28.65% after AHCS. Coagulation necrosis was produced in the target area. The tumor markers deceased significantly after AHCS. Tumor-load reduction after AHCS was more significant than after TACE. Suppression of cellular immunity after TACE was significant. In contrast, CD3^＋, CD4^＋ and NK increased after AHCS and an abnormal T-lymphocyte distribution was corrected. Quality of life after AHCS increased according to the EORTC QLQ-C30 evaluation. No severe complications occurred. CONCLUSION Percutaneous AHCS cryoablation after TACE reduced the tumor load in the short term. At the same time, cellular immune function was increased after AHCS. TACE was critical in increasing the therapeutic efficacy of AHCS because of its embolisation of blood vessels preventing a Flow Effect. Reduction of the tumor load in the short term may conduce to increase cellular immunity. Percutaneous AHCS cryoablation combined with TACE can reduce the tumor load, improve cellular immunity and increase quality of life of HCC patients. This type of therapy deserves to be studied further research.

Clinicopathological significance of loss of heterozygosity and microsatellite instability in hepatocellular carcinoma in China

AIM: To determine the features of microsatellite alterations and their association with clinicopathological characteristics of hepatocellular carcinoma (HCC). METHODS: Loss of heterozygosity (LOH) and microsatellite instability (MSI) of 55 microsatellite loci were detected with PCR-based microsatellite polymorphism analyses in tumors and corresponding noncancerous liver tissues of 56 surgically resected HCCs using the MegaBACE 500 automatic DNA analysis system.RESULTS: LOH was found in 44 of 56 HCCs (78.6%) at one or several loci. Frequencies of LOH on 1p, 4q, 8p,16q, and 17p were 69.6% (39/56), 71.4% (40/56), 66.1% (37/56), 66.1% (37/56), and 64.3% (36/56), respectively. MSI was found in 18 of 56 HCCs (32.1%) at one or several loci. Ten of fifty-six (17.9%) HCCs had MSI-H. Serum HBV infection, alpha-fetoprotein concentration, tumor size, cirrhosis, histological grade, tumor capsule, as well as tumor intrahepatic metastasis, might be correlated with LOH on certain chromosome regions. CONCLUSION: Frequent microsatellite alterations exist in HCC. LOH, which represents a tumor suppressor gene pathway, plays a more important role in hepatocarcinogenesis. MSI, which represents a mismatch repair genepathway, is a rare event during liver carcinogenesis. Furthermore, LOH on certain chromosome regions may be correlated with clinicopathological characteristics in HCC.

Hepatitis B and alcohol affect survival of hepatocellular carcinoma patients

AIM: In the USA, Hawaii has the highest incidence of hepatocellular carcinoma (HCC) and a diverse population.It is an ideal place to characterize HCC in the context of ethnicity/risk factors.METHODS: A total of 262 cases of HCC (1992-2003) were retrospectively reviewed for demographics, ethnicity, birthplace, viral hepatitis, alcohol use, diabetes, smoking and risk factors for viral hepatitis such as intravenous drug abuse (IVDA), transfusions, tattoos and vertical transmission. Tumor stage, Child's class, Cancer of the Liver Italian Program (CLIP) score, α-fetoprotein level, treatment and survival were recorded.RESULTS: Gender, age, viral hepatitis, alcohol, IVDA, and diabetes differed significantly in Asians, non-Asians and Pacific Islanders. There were also specific differences within Asian subgroups. Alpha-fetoprotein, smoking, transfusions, stage and resectability did not differ between groups. Asians were more likely to have hepatitis B, while non-Asians were more likely to have hepatitis C. Factors that decreased survival included hepatitis B, alcohol, elevated alpha-fetoprotein, CLIP ＞2 and increased Child's class. When Asians were combined with Pacific Islanders, median survival (1.52 years vs 3.54 years), 1- and 3-year survival was significantly worse than those for non-Asians. After Cox regression analysis for hepatitis B and alcohol, there was no difference in survival by ethnicity.CONCLUSION: Various ethnicities have different risk factors for HCC. Hepatitis B, alcohol, and α-fetoprotein are more important factors for survival than ethnicity.

Expression of Interleukin-11 and Interleukin-11 receptor a in human colorectal adenocarcinoma; Immunohistochemical analyses and correlation with clinicopathological factors

AIM： There is strong evidence that interleukin-11 （IL-11） is involved in the regulation of tumor progression, cellular growth and differentiation. Recently, interleukin-11 receptor （IL-11R） has been detected on some cancer cells. In this study, we investigated the expression of IL-11 and IL-11R in colorectal adenocarcinoma. METHODS： To elucidate the involvement of IL-11 and IL-11Rα in human intestinal adenocarcinomas, we examined 115 cases of surgically resected human colonic adenocarcinoma and 11 cases of adenoma by immunohistochemistry and Western blotting. RESULTS： Among 115 cases of adenocarcinoma, 100 cases （87.0%） showed positive staining in the cytoplasm of carcinoma cells for the IL-11, and 87 cases （75.6%） were positive for the IL-11Ra. Six cases （54.5%） and four cases （36.4%） of 11 adenomas were positive for IL-11 and IL-11Ra, respectively. The expression of IL- 11Ra correlated with the histological differentiation （P=0.033503）, the depth of tumor invasion （P= 0.006395）, Dukes＇ classification （P= 0.015648） and lymphatic invasion （P= 0.003865）. However, the expression of IL- 11Rα was not correlated with the venous invasion and the presence of lymph node metastasis. The expression of IL-11 was not correlated with any clinicopathological factors. In Western blot analysis, two human colorectal carcinoma cell lines and four tissues of surgically resected human carcinoma expressed both IL-11 and IL-11Rα proteins. CONCLUSION： IL-11 and IL-11Rα are highly expressed in human colorectal adenocarcinoma and the IL-11Rα expression is correlated with clinicopathological factors, These findings suggest that the expression of IL-11Rα is an important factor for the invasion of human colorectal adenocarcinoma.

DEC1 nuclear expression:A marker of differentiation grade in hepatocellular carcinoma

AIM: To investigate the expression patterns of human differentiated embryo chondrocyte 1 (DEC1) in hepatocellular carcinoma (HCC) and corresponding adjacent non-tumor and the normal liver tissues, the association between DEC1 expression and histopathological variables and the role of DEC1 in hepatocarcinogenesis. METHODS: The expression of DEC1 was detected immunohistochemically in 176 paraffin-embedded sections from 63 patients with HCC and 50 subjects with normal liver tissues. RESULTS: DEC1 protein was persistently expressed in the cytoplasm of hepatocytes in normal liver and HCC tissues. Compared with adjacent non-tumor liver tissues, HCC tissues showed high nuclear expression of DEC1 protein. However, high DEC1 nuclear expression was more frequently detected in well-differentiated (83.3%) than in moderately (27.3%) and poorly differentiated HCC (16.7%). Low DEC1 expression was associated with poor histological differentiation and malignancy progression. A correlation was found between the nuclear expression of DEC1 protein and histological differentiation (r = 0.376, P = 0.024). CONCLUSION: DEC1 is expressed in the cytoplasm of hepatocytes and because nuclear DEC1 expression is decreased with decreasing differentiation status of HCC, nuclear DEC1 might be a marker of HCC differentiation.

Application of non-small cell lung cancer pleural effusion cell blocks in molecular pathological detection

Objective: The tumor tissues used in molecular pathological detection were usually obtained by surgery, which would cause trauma and may not be suitable for the terminal cancer patients. This paper evaluated the value of the non-small cell lung cancer(NSCLC) pleural effusion cell blocks as tumor tissues replacement materials in the application of molecular pathological detection. Methods: Tumor cells were made into cell blocks through stratified centrifugal from 30 NSCLC patients with the pleural effusion. The immunohistochemistry, fluorescence in situ hybridization(FISH) and gene sequencing methods were employed in our experiments. Results: The tumor cells of cell block section were rich and could keep part of histological structure. Immunohistochemistry staining could assist diagnosis and tumor parting. Epidermal growth factor receptor(EGFR) FISH-positive was found in 33.33% of the group, high polysomy in 6 cases, amplification in 4 cases. EGFR gene mutations were found in 8 cases of 30 samples, with an incidence of 26.67%, 6 cases were detected in the exon 19, and 2 cases were detected in the exon 21. Conclusion: The NSCLC pleural effusion cell blocks are useful for the diagnosis and determining the primary source of tumor, instructed targeted therapy.

Renal Collecting Duct Cancer： a Report of 2 Cases

Renal collecting duct cancer is a rare malignant tumor, which accounts for 1% to 2% of epithelial kidney tumors. Its pathologial appearance has been easily misdiagnosed as a mammilliform renal cell carcinoma or as other tumors. The malignancy of renal collecting duct cancer is high, with early metastasis and poor prognosis. The clinical data for 2 cases of the tumor are discussed in this report, including reports on the histopathology and the changes in immunohistochemistry.

EXPRESSION OF P53 GENE IN ORAL SQUAMOUS CELL CARCINOMA AND ITS RELATION WITH CLINICAL AND PATHOLOGICAL PARAMETERS AND PROGNOSIS OF PATIENTS

One hundred and eleven cases of oral squamous cell carcinoma (OSCC) were examined for overexpression of p53 protein by using immunohistochemical technique. Association between p53 protein overexpression and clinical and pathological parameters as well as prognosis of patients were also analyzed. p53 protein overexpression was commonly observed (69. 4%) in OSCC and may be used as a marker of carcinogenesis of OSCC. The level of p53 protein overexpression is correlated with the lower three and five-year survival rate of OSCC. The presence or absence of p53 overexpression was not correlated with sex, age, site of tumor, size of tumor, degree of differentiation,node status,and clinical stage in OSCC. Single factor COX proportional hazards regression model analysis indicated that there was no significant association between p53 overexpression and prognosis of OSCC. Multivariable COX model analysis failed to establish effective life function or risk rate function. These showed that all the parameters analyzed in this study as well as p53 overexpression were not significant and effective risk factors of prognosis for patients with OSCC.

Multicentricity and its associated factors in renal cell carcinoma

OBJECTIVE: To investigate the incidence and associated factors of multicentricity in renal cell carcinoma (RCC) in Chinese patients. METHODS: One hundred and two kidney samples from radical nephrectomy due to RCC were step sectioned at 3 mm intervals and examined. All tissue abnormalities were removed, stained and examined for multicentricity. Then, on each slice of the sample, both the parenchymal margin of 15 mm beyond the pseudocapsule and tissue around the renal sinus were continuously sectioned and examined for completeness of the pseudocapsule and vascular and lymph node invasion. The relationship between muliticentricity and other pathological parameters was evaluated. RESULTS: The incidence of multicentricity was 15.7% (16/102); it was significantly lower in primary tumors 4.0 cm (4.9%, 2/41 vs 23.0%, 14/61; chi(2) = 6.055, P = 0.014). The incidence was 9.8% (8/82) in tumors without vascular invasion and 40.0% (8/20) in those with it (P = 0.003, Fisher's exact test). The incidence of multicentricity was 1.9% (1/53) in tumors with a complete pseudocapsule and 30.6% (15/49) in those without it (chi(2) = 15.885, P = 0.000). The grade, stage, subtypes and lymph node invasion of the primary tumor were not significantly associated with multicentricity. Multiple logistic regression analysis showed that pseudocapsular incompleteness and vascular invasion were two significant predictors of RCC multicentricity (P = 0.005 and 0.023). CONCLUSIONS: The incidence of multicentricity of RCC in this group of patients was in accordance with published studies. Multifocality was significantly associated with tumor size, pseudocapsule completeness and vascular invasion. NSS should be limited to tumors less than 4.0 cm when the contralateral kidney is normal and careful long-term follow-up is necessary in tumors with positive vascular invasion and incomplete pseudocapsule.