尿脱落细胞FISH检测在膀胱癌诊断中的应用

目的:研究尿脱落细胞FISH检测提高膀胱癌早期诊断的可行;方法:收集68例腺膀胱炎患者晨尿通过FISH检测GLP p16、CSP3、CSP17和CSP7染色体异常信号,并用统计学方法计算出阈值.为了验证FISH检测的优越,实验选取临床诊断膀胱癌最常用的尿脱落细胞学检测作为研究对照方法,收集100例疑似膀胱癌患者尿液标本,分别对尿脱落细胞和FISH检查诊断膀胱癌的敏感、特异、FISH检测与膀胱癌临床及病理特征的关系进行统计学分析.结果:100例疑似膀胱癌患者尿脱落细胞及FISH检测的阳率分别为56.0％ (56/100)和77.0％(77/100),敏感度分别为56.10％(46/82)和82.02％(73/89),经统计学分析两种检查方法之间的差异具有统计学意义.FISH检测的敏感和总阳率明显高于尿脱落细胞,而特异两者差异无统计学意义.FISH检测与膀胱癌的病理分级和临床分期均无相关.结论:FISH检测技术是能够成为提高膀胱癌早期诊断的一种新技术.     

应用荧光原位杂交技术诊断尿路上皮癌的临床研究

背景与目的：尿路上皮癌是一种最常见的泌尿系统肿瘤,尿细胞学检查是诊断尿路上皮癌的经典方法,虽然特异度较高,但是敏感度偏低。目前荧光原位杂交技术（fluorescence in situ hybridization,FISH）计数分裂间期细胞的染色体倍数已成功应用于遗传学和肿瘤学研究领域。本研究旨在评价FISH在诊断尿路上皮癌中的诊断价值。方法：采用FISH检测100例血尿患者尿脱落细胞中3、7、9和17号染色体数目异常,以组织病理确诊为尿路上皮癌为金标准,评估FISH诊断的特异度和敏感度,并与尿细胞学检查结果做比较。结果：FISH诊断尿路上皮癌特异度为92.3%,敏感度为74.7%;尿细胞学诊断特异度为100%,敏感度为46.0%。两者相比,敏感度差异有统计学意义（P〈0.05）,而特异度差异无统计学意义（P〉0.05）。结论：与尿细胞学相比,FISH诊断尿路上皮癌具有较高的特异度和相似的特异度敏感度,可作为诊断尿路上皮癌的新方法。     

尿脱落细胞端粒酶活性检测在膀胱癌早期诊断中的价值

目的 探讨膀胱癌早期诊断的新的无创性检查方法。方法 应用端粒酶活性ＰＣＲ－ＥＬＩＳＡ法和细胞学方法对５３例膀胱癌、２６例良性膀胱疾病和１７例正常人尿脱落细胞进行检测,并对２种方法检测的阳性率以及病理检查结果进行比较。结果 ＰＣＲ－ＥＬＩＳＡ法检测膀胱癌患者尿脱落细胞端粒酶活性的总阳性率（６４．２％）明显高于尿细胞学检查的总阳性率（３９．６％）;在早期、低给别膀胱癌（Ｔ１、Ｇ１）中,端粒酶活性阳性率     

18F-FDG和18F-FLT PET显像对肺恶性结节诊断价值Meta分析

目的：应用循证医学及Meta分析方法评估18F-脱氧葡萄糖（fluorodeoxyglucose,FDG）和18F-脱氧胸腺嘧啶核苷（fluorothymidine,FLT）正电子发射断层扫描（positron emission tomography,PET）在肺恶性结节诊断中的价值。方法：检索PubMed、0vid、Cochrane图书馆、CNKI、万方数据库和中文科技期刊数据库等,依据纳入及排除标准筛选文献,按照诊断精确性研究的质量鉴定（quality assessment of studies of diagnostic accuracy included in systematic reviews,QUA—DAS）标准行质量评价,提取数据并用Meta—disc 1．4软件行Meta分析,计算合并敏感度、合并特异度、汇总受试者工作曲线（summary receiver-operating characteristic curves,SROC）及曲线下面积（areas under the curve,AUC）等。结果：最终纳入7篇文献。FDGPET敏感度为0．844,95％CI：0．791～0．888,特异度仅为0．477,95％CI：0．405～0．549;FLTPET敏感度为0．784,95％CI：0．725～O．835,特异度为0．677,95％CI：0．606～0．742;FDG和FLT的SROCAUC分别为0．7570和0．8201,P=0．273。结论：FDGPET对肺部恶性病变敏感性很高但特异度差,FLTPET敏感性和特异度较均衡;在肺部恶性肿瘤的诊断中,FLT尚不能代替FDG的应用;FDGPET的优势在于探寻隐匿的肿瘤病灶和肿瘤分期等方面;FLTPET的优势在于减少炎性反应所致的假阳性结果。     

颈部淋巴结细针穿刺细胞学检查的临床应用

目的：探讨颈部淋巴结细针穿刺的临床应用价值。方法：回顾性分析我院2002年3月1日～2005年4月1日931例颈部淋巴结细针穿刺涂片细胞学检查与术后病理切片结果对比的临床资料。结果：931例颈部肿大淋巴结的细针穿刺诊断敏感度（总符合率）为82．5％。细针抽吸诊断良性病变350例（37，6％），恶性痛变491例（52．8％），可疑恶性20例（2．1％），诊断不明70例（7．5％）。本组细针穿刺良性病变诊断敏感度85．3％，总准确率为91.4％；恶性病变诊断敏感度94．4％，总准确率为96．0％；恶性淋巴瘤诊断敏感度为64％，总准确率为94．7％；转移癌诊断敏感度为92．6％，总准确率95．7％。结论：针吸细胞学检查是一种可靠的、准确率较高的颈部淋巴结病理诊断检查方法，值得临床推广使用。     

尿脱落细胞微卫星DNA改变在膀胱癌早期诊断中的应用

目的 利用检测尿脱落细胞微卫星ＤＮＡ序列（ｍｉｃｒｏｓａｔｅｌｌｉｔｅ,ＭＳ）改变,建立早期诊断膀胱癌的方法。方法 选择１０对微卫星ＭＳ引物,利用聚合酶链反应（ＰＣＲ）方法,以自身外周血和膀胱癌组织为对照,检测２８例膀胱癌患者尿脱落细胞中ＭＳ的失杂合（ｌｏｓｓ ｏｆ ｈｅｔｅｒｏｚｙｇｏｓｉｔｙ,ＬＯＨ）和不稳定性（ｍｉｃｒｏｓａｔｅｌｌｉｔｅ ｉｎｓｔａｂｉｌｉｔｙ,ＭＩＮ）。结果 ２８例膀胱癌患者中,２４例（８５．７％）尿脱落细胞至少在１个ＭＳ位点存在ＬＯＨ或ＭＩＮ改变,３例（１０．７％）脱落细胞学检查阳性患者尿脱落细胞均检出ＬＯＨ或ＭＩＮ。同一患者尿脱落细胞与癌组织ＬＯＨ改变一致率为９４．１％。１５例正常人悄脱落细胞中未见ＭＳ的改变。结论 利用检测尿脱落细胞ＭＳ改变诊断膀胱癌,比常规的细胞学检查更敏感、更     

BTA检测在膀胱癌诊断中的价值

目的BTA检测与尿脱落细胞学检查结果比较,以明确在膀胶癌诊断中的应用价值.方法 收集1996年12月～1997年1月经膀胱镜及病理学检查确诊为膀胱乳头状移行细胞癌的病人共47例.每一例于膀胱镜检查前连续留取三次晨尿,行尿脱落细胞学检查.最后一次标本同时行BTA检测及尿液常规化验.结果BTA检测膀胱癌的敏感度为70.2%(33/47),尿脱落细胞学检查敏感度为25.5%(12/47),两者有非常显著性差异(P<0.001).共有8例(17.0%)患者两种检查结果均为阳性,10例(21.3%)患者两种检测结果均为阴性.另外,BTA检测对T1期膀胱癌患者的敏感度明显高于尿脱落细胞学检查,其结果分别为76.0%(19/25)和12.0%(3/25),统计学分析示有非常显著性差异(P<0.01).结论 BTA检测是一种有价值的膀胱癌诊断辅助措施,且使用方便,检测迅速,无创伤性,便于临床开展.     

端粒酶活性检测在膀胱肿瘤早期诊断中的应用

目的：探讨检测端粒酶活性在膀胱癌早期诊断中的临床意义。方法：采用TRAP-PCR-ELISA法检测32例膀胱癌患者尿液和膀胱冲洗液中脱落细胞、膀胱癌组织、20例正常膀胱组织及14例非膀胱肿瘤患者尿液脱落细胞中端粒酶活性，并行尿脱落细胞学检查。结果：32例膀胱癌患者尿液脱落细胞、膀胱冲洗液脱落细胞、膀胱癌组织中端粒酶活性阳性率分别为65．6％（21／32）、71．9％（23／32）和84．0％（27／32），20例正常膀胱组织端粒酶活性均为阴性，14例非膀胱肿瘤患者尿液中1例端粒酶活性阳性。端粒酶活性阳性表达与肿瘤的分级、分期之间差异无明显相关性（P〉0．05），敏感性明显高于脱落细胞病理学检查。结论：尿液、膀胱冲洗液脱落细胞端粒酶活性测定敏感性较高．可用于膀胱癌的早期诊断。     

宫颈细胞学、人乳头瘤状病毒检测及阴道镜在宫颈癌前病变诊断的应用

目的：探讨人乳头瘤状病毒DNA检测与细胞学检查及阴道镜检查对宫颈癌前病变的诊断价值。方法：2007年1月～2008年1月体检发现宫颈病变的患者173例,均进行宫颈刮片、高危型HPV检测及阴道镜检查,对一项或多项异常者行病理组织学检查,以病理结果为金标准。结果：高危型HPV—DNA检测的敏感度为83．82％;巴氏涂片以ASCUS为分界点的敏感度为49．71％;联合宫颈细胞学检查、HPV—DNA检测及阴道镜下病理检查的敏感度最高为95．95％。结论：联合采用宫颈细胞学检查、HPV—DNA检测及阴道镜下病理检查能及早发现宫颈癌前病变,提高检出率,降低假阴性。     

细胞角蛋白20对膀胱癌早期诊断的前瞻性研究

目的：评估细胞角蛋白20（CK20）标志物作为膀胱癌早期诊断及临床监测的价值。方法：对62例患者的尿液进行尿脱落细胞学及CK20标志物免疫荧光检测的前瞻性研究。分析参数包括肿瘤数目、大小及WHO分级，术前或活检前尿脱落细胞学和CK20标志物。结果：病理活检证实15例移行细胞癌中，CK20为13例阳性，2例阴性；47例非膀胱癌中，CK20标志物2例假阳性。与尿脱落细胞学比较，CK20标志物对膀胱移行细胞癌诊断的特异性和阳性预报值更高，分别为96．0％比82．5％（U＝2．18，P＜0．05），86．7％比52．4％（U＝2．16，P＜0．05）；但两者在敏感性和阴性预报值间无显著性差异（U值分别为：0．91和1．02，P＞0．05）。CK20表达与肿瘤分级间无明显相关性。结论：CK20是诊断膀胱移行细胞癌的一种良好标志物，其特异性明显优于尿脱落细胞学。     

应用荧光原位杂交技术检测膀胱癌的研究

目的应用荧光原位杂交((fluorescence in situ hybridization,FISH)技术检测膀胱癌患者尿液脱落细胞中染色体异常,评估FISH在中国人群中诊断膀胱癌的作用。方法2007年1月至2008年8月,随机留取20例良性前列腺增生症患者的新鲜尿液,用3号和7号、17号及p16位两组混合探针,通过在尿液脱落细胞标本上进行FISH检测,建立正常人群的阈值;其后随机留取30例门诊膀胱镜活检证实的膀胱癌患者的尿液,同时进行尿液脱落细胞的细胞形态学分析及FISH检测,对比检查结果。结果3号、7号和17号染色体非整倍性改变及p16位点异常正常阈值分别为8.5%、7.1%、6.8%和9.2%,FISH与细胞学检查总敏感性分别为76.6%和43.3%(P<0.05)。T_(is)及T_a、T_1患者FISH检测的敏感性分别为80.0%和64.2%,脱落细胞组织学检测显示敏感性分别为40.0%和35.7%;T_(2-3)患者FISH的敏感性为90.9%,而脱落细胞组织学检测为54.7%(P<0.05),低级别尿路上皮癌FISH及细胞学敏感性分别为68.4%和31.6%;高级别分别为90.9%和63.6%。结论与尿液脱落细胞组织学检测相比,对尿液脱落细胞进行FISH检测可以提高膀胱癌的诊断率,FISH可以作为诊断膀胱癌的一种无创伤的新方法。     

尿液中尿膀胱癌抗原和钙网蛋白联合检测对原发性膀胱癌的诊断价值

目的评价尿液中尿膀胱癌抗原（UBC）和钙网蛋白（CRT）联合检测对原发性膀胱癌的诊断价值。方法 76例膀胱癌患者、50例泌尿系统良性疾病患者均在膀胱镜检查前留取尿液,用ELISA法进行UBC、CRT定量检测,同时进行尿液中脱落细胞学检测。结果 UBC和CRT诊断膀胱癌的敏感性分别为89.47%和82.89%,高于脱落细胞学的51.32%（P〈0.05）;3种诊断方法对膀胱癌的诊断特异性分别为92.00%、78.00%和94.00%。联合检测UBC和CRT诊断膀胱癌的敏感性和特异性高达94.74%、94.00%。结论尿液中UBC和CRT是早期诊断膀胱癌较好的肿瘤标志物,而两者联合检测能进一步提高诊断效率。     

Sensitive detection of transitional cell carcinoma of the bladder by microsatellite analysis of cells exfoliated in urine.

Transitional cell carcinoma (TCC) is the most common bladder tumor. Urine cytology can identify most high-grade tumors but sensitivity is lower if one includes lesions of all grades. Microsatellite marker alterations have been found in many tumor types including bladder cancer and have been used to detect cancer cells in body fluids including urine. The aim of our study is to further evaluate feasibility and sensitivity of microsatellite analysis to detect bladder cancer cells in urine. We studied 55 individuals: 21 with symptoms suggestive of bladder cancer, 23 patients with previous history of TCC and 11 healthy subjects. Genomic DNA was extracted from blood lymphocytes, urine sediment, bladder washings and tumor or normal bladder mucosa. Twenty highly informative microsatellite markers were analyzed for loss of heterozigosity (LOH) and microsatellite instability (MIN) by polymerase chain reaction. Microsatellite analysis of urine identified 33 of 34 (97%) patients with either primary or tumor recurrence, whereas urine cytology identified 27 of 34 (79%) patients (p = 0.0001). Detection of microsatellite abnormalities improved the sensitivity of detecting low-grade and/or stage bladder tumor: from 75-95% for grades G1-G2 and from 75-100% for pTis-pTa tumors. Bladder washings from 25 patients were also analyzed, and in all cases results were identical to those obtained from voided urine. None of the 16 patients without evidence of TCC showed LOH and/or MIN in urine samples or bladder washings. Interestingly, in a patient with persistent bladder mucosa abnormalities, microsatellite alterations were demonstrated 8 months before the histopathologic diagnosis of tumor recurrence. These results further indicate that microsatellite marker analysis is more sensitive than conventional urine cytology in detecting bladder cancer cells in urine and represents a potential clinical tool for monitoring patients with low-grade/stage TCC.     

Combined morphologic and fluorescence in situ hybridization analysis of voided urine samples for the detection and follow‐up of bladder cancer in patients with benign urine cytology

BACKGROUND.

Bladder cancer is among the 5 most common malignancies worldwide. Patients with bladder cancer are closely followed with periodic cystoscopies and urine cytology analyses due to the significant risk of tumor recurrence. The UroVysion fluorescence in situ hybridization (FISH) test demonstrated higher sensitivity over urine cytology in detecting bladder cancer by most comparative studies.

METHODS.

In the current study, the diagnostic usefulness of a combined cytology and FISH analysis approach was tested using the Duet automatic scanning system in patients with benign urine cytology who were being monitored for recurrent urothelial carcinoma or being assessed for various urologic symptoms.

RESULTS.

By combining the benefits of conventional cytology with molecular diagnostics, a more sensitive detection of bladder cancer was attained. All patients who had positive cystoscopy concomitantly with urine sampling were detected by combined analysis. Additional patients that developed transitional cell carcinoma during a follow‐up period of 24 months had a previous positive result on combined analysis. Only 2 patients with a negative combined analysis result presented with late disease recurrence (20 months and 22 months, respectively, after the negative test). Therefore, negative combined analysis was found to be predictive of a lack of disease recurrence for at least 12 months. In this timeframe, the overall sensitivity, specificity, negative predictive value (NPV), and positive predictive values of the combined analysis test were 100%, 65%, 100%, and 44%, respectively.

CONCLUSIONS.

Given the absolute sensitivity and NPV of the combined analysis test, the management of patients with a negative combined analysis result might be revised and allow for more flexible assessment and management of bladder cancer patients relying more on urine bound tests. Cancer (Cancer Cytopathol) 2007. © 2007 American Cancer Society.     

Diagnostic Evaluation of Urinary Angiogenin (ANG) and Clusterin (CLU) as Biomarker for Bladder Cancer

Bladder carcinoma is an important worldwide health problem. Both cystoscopy and urine cytology used in detecting bladder cancer suffer from drawbacks where cystoscopy is an invasive method and urine cytology shows low sensitivity in low grade tumors. This study validates easier and less time-consuming techniques to evaluate the value of combined use of angiogenin and clusterin in comparison and combination with voided urine cytology in the detection of bladder cancer patients. This study includes malignant (bladder cancer patients, n?=?50), benign (n?=?20) and healthy (n?=?20) groups. The studied groups were subjected to cystoscopic examination, detection of bilharzial antibodies, urine cytology, and estimation of urinary angiogenin and clusterin by ELISA. The overall sensitivity and specificity were 66 and 75 % for angiogenin, 70 and 82.5 % for clusterin and 46 and 80 % for voided urine cytology. Combined sensitivity of voided urine cytology with the two studied biomarkers was 88 % which is higher than the combined sensitivity of both markers alone (82 %) and that of the cytology with each marker (76 and 80 %) for angiogenin and clusterin respectively. In conclusion, combined use of the cytology with the studied biomarkers can improve the sensitivity for detecting bladder cancer, and may be very useful in monitoring the effectiveness of antiangiogenic and apoptotic therapies in bladder cancer.     

膀胱癌荧光原位杂交检测及其临床意义

目的:分析膀胱移行细胞癌的染色体畸变情况,探讨荧光原位杂交(FISH)技术在膀胱癌的临床应用价值.方法:采用3、7、17号染色体着丝粒探针和9号染色体p16基因位点探针对56例膀胱移行细胞癌患者和20名健康人群的新鲜尿液进行FISH检测,统计染色体的畸变并分析其与病理分级、分期的关系.对所有病例同步进行尿细胞学分析.结果:膀胱癌患者尿脱落细胞核中3、7、17号染色体及9号染色体p16基因畸变率分别为58.9%、39.3%、58.9%和75.0%,各染色体畸变在膀胱癌不同分期之间的差异无统计学意义(P>0.05),3、7、17号染色体畸变在不同分级之间的差异具有统计学意义(P<0.05),四染色体探针组合诊断膀胱癌的总阳性率为80.4%;膀胱癌尿脱落细胞的FISH检出率明显高于尿细胞形态学.结论:膀胱癌的发生发展与染色体的畸变有关,膀胱癌尿脱落细胞的FISH检测,对膀胱癌的早期诊断、预后评估及复发监测等具有重要价值.     

尿细胞角蛋白检测与尿脱落细胞学检查在膀胱癌诊断中的价值

目的:探讨尿细胞角蛋白检测与尿脱落细胞学检查在膀胱移行细胞癌诊断中的价值。方法:136例怀疑膀胱癌者,进行尿细胞角蛋白8和18的含量(UBC值)。检测与尿细胞学检查,其中87例经组织学证实为膀胱移行细胞癌。比较两者诊断膀胱癌的敏感性和特异性。结果:尿细胞角蛋白的敏感性为70.1%,特异性为73.3%;尿细胞学的敏感性为42.5%,特异性为83.7%。尿细胞角蛋白在膀胱癌不同分级和分期中的敏感性优于尿细胞学(P<0.05)。结论:尿细胞角蛋白的检测在早期诊断膀胱癌方面优于尿细胞学检查,可作为膀胱癌的早期检测指标。     

RT-PCR法检测尿脱落细胞中XIAP的表达在膀胱癌诊断中的价值

目的：比较膀胱癌患者尿液脱落细胞中XIAP表达的RT-PCR检测法和常规尿脱落细胞病理学检测在膀胱癌诊断中的临床价值。方法：采用逆转录聚合酶链反应技术（RT-PCR）检测51例膀胱尿路上皮癌患者尿液脱落细胞中XIAP-mRNA的表达,同时行常规尿脱落细胞病理学检测,20例非肿瘤人员作为对照组。结果：实验组51例尿脱落细胞XIAP-mRNA RT-PCR检测阳性27例（53%）,尿脱落细胞学病理学检测阳性12例（24%）,对照组20例尿脱落细胞XIAP-mRNA检测阳性1例（5.0%）,对照组尿脱落细胞病理学检测阳性0例（0%）。实验组RT-PCR检测膀胱尿路上皮癌患者尿脱落细胞中XIAP表达的敏感性高于尿脱落细胞病理学检测,差异有极显著统计学意义（P〈0.01）,实验组RT-PCR检测膀胱尿路上皮癌患者尿中XIAP表达的敏感性显著高于非肿瘤对照组,差异有极显著统计学意义（P〈0.01）。结论：膀胱尿路上皮癌患者尿脱落细胞中XIAP表达的RT-PCR检测法较常规尿脱落细胞病理学检测更敏感,临床上作为膀胱癌的筛选方法,有一定的临床价值。     

Examination of Diagnostic Accuracy of UroVysion Fluorescence In Situ Hybridization for Bladder Cancer in a Single Community of Japanese Hospital Patients

Objective: UroVysion (Abbott Molecular, Inc., Illinois, USA) is based on multicolor fluorescence in situ hybridization(FISH). It has been used successfully in the USA following its Food and Drug Administration approval in 2001. However,the technology was not approved for use in Japan until 2017. Cystoscopy and urine cytology are the most frequentlyused examinations to detect bladder cancer in Japan, and there are only a few reports regarding the performance ofUroVysion. Therefore, the aim of this study is to examine the diagnostic accuracy of UroVysion FISH in Japanesepatients whose tumors are detected by cystoscopy before transurethral resection of bladder tumor (TURBT). Methods:From April 2018 to July 2018, a total of 40 patients who were diagnosed as having bladder tumors by cystoscopy, andtherefore underwent TURBT were registered in this study. One day before TURBT, urine cytology and UroVysionFISH were used in order to compare the accuracy with which they could detect bladder carcinoma, as confirmed bypathological results of TURBT. Results: The pathological results of TURBT showed urothelial carcinoma in 33 cases.Urine cytology showed positive results for 0 cases (0%), suspicious results for 10 cases (30.3%), and negative resultsfor 23 cases (69.7%). On the other hand, UroVysion FISH indicated 9 positive cases (27.3%) and 24 negative cases(72.7%). There were 19 cases of urothelial carcinoma (57.6%) that were not detected by either method. Conclusion:We conclude that UroVysion FISH alone is insufficient to detect bladder cancer and that cystoscopy is essential for theoptimum detection or follow up of bladder cancer cases in our hospital.     

Improved detection of bladder carcinoma cells in voided urine by standardized microsatellite analysis

Successful treatment of bladder cancer depends largely on early diagnosis of primary and recurrent disease. Sensitive, specific and noninvasive procedures for detection are especially needed for grade 1 and 2 bladder tumors, because of the relatively low sensitivity of cytology. Here we introduce a novel strategy to improve the sensitivity and reliability of microsatellite analyses by employing marker-specific threshold values for loss-of-heterozygosity (LOH) at 10 loci. These individual cut-offs were experimentally determined with 35 normal control tissues and subsequently validated in a retrospective study with bladder cancer biopsies from 86 patients. In a prospective analysis of voided urines samples and matched blood probes from 91 patients, LOH-analysis, UroVysion FISH and conventional urine cytology were compared with histological findings of consecutive transurethral biopsies. Whereas all samples could be analyzed by our LOH assay, only 56 samples were suitable for all 3 analyses. The highest sensitivity was obtained with our LOH-assay/cytology approach (G1-2: 72%; G3: 96%) being only surpassed by a combination of all 3 techniques (G1-2: 83%; G3: 100%). Since over 93% of the patients with recurrent disease were identified by LOH/cytology-analyses of their voided urine samples, a monitoring scheme alternating cystoscopy with LOH/cytology-examination could now be envisioned to reduce invasive interventions and consequently improve follow-up compliance, especially in patients with low grade tumors.