中国单中心肺腺癌患者基因突变特征及与欧美肺腺癌人群比较分析

目的 探讨肺腺癌的基因突变特征及其意义,为靶向用药提供依据。方法 利用高通量测序平台靶向捕获测序技术,检测昆山市第一人民医院2017年5月至2018年8月确诊的104例肺腺癌患者的56个癌相关基因突变情况。分析肺腺癌基因突变特征并与欧美肺腺癌人群基因突变特征进行比较,分析基因突变与临床特征相关性并筛查靶向用药位点。结果 104例肺腺癌患者中,84例(81%)检测到34种基因突变,前4位高频突变基因包括表皮生长因子受体(EGFR)(49%,51/104)、TP53(21%,22/104)、KRAS(13%,14/104)、BRAF(6%,6/104)。检测到的187个突变中,76%(142个)为错义点突变,13%(24个)为小片段缺失,6%(12个)为拷贝数扩增,3%(5个)为小片段插入,2%(4个)为无义突变。104例肺腺癌患者中,68例(65%)检测到涉及13个基因的34种靶向用药相关基因的突变,其中19例(18%)检测到≥2种靶向用药相关基因突变。女性患者比男性患者更容易发生EGFR基因突变[62%(34/55)比35%(17/49),χ2=7.629,P=0.006],男性患者比女性患者更容易发生KRAS基因突变[22%(11/49)比5%(3/55),χ2=6.424,P=0.011]。EGFR、TP53、KRAS、CDKN2A基因在昆山市第一人民医院与欧美肺腺癌人群中的突变率差异均有统计学意义(均P<0.05)。结论 肺腺癌的基因突变特征较为复杂,且在不同人群中的差异较大。基于高通量测序技术的多基因联合检测可相对全面地揭示患者肿瘤相关基因突变特征,对个体化的靶向用药指导、耐药监测及预后评估有一定的意义。     

消化道恶性肿瘤高通量基因测序的生物统计分析

目的:观察TP53、KRAS、KDR、APC、MLH1及PIK3CA等56个基因在消化道恶性肿瘤中的突变情况,探讨驱动基因的诊疗意义。方法:选择胃食管癌15例、结直肠癌21例患者组织石蜡标本,运用高通量基因测序技术检测56个肿瘤突变高频基因,并进行生物统计分析。结果:36例标本检出34例有已知基因突变,突变基因为TP53、KRAS、MLH1、PIK3CA、KDR、APC、SMARCB1、KIT、EGFR、NRAS、STK11、SMO、SMAD4、CDH1、ERBB2、JAK2和RET共17种。其突变率由高到低依次为:TP53（75.00%）,KRAS（33.33%）,MLH1、PIK3CA、KDR（均为13.89%）,APC（11.76%）,SMARCB1（8.82%）,KIT、EGFR及NRAS（均为2.78%）。KRAS在结直肠癌中的突变率（47.62%）显著高于在胃食管癌中的突变率（13.33%）。TP53的突变率明显高于其他突变基因。在结直肠癌中KRAS的突变率显著高于KDR、APC、MLH1,未发现有统计学关联。结论:消化道恶性肿瘤TP53突变率较高,可能与病理组织分化程度低及淋巴结转移有关。KRAS在结直肠癌中较在胃食管癌中更易发生突变,存在部位差异。同时KRAS与KDR、APC、MLH1,在结直肠癌患者中存在共突变现象,提示结直肠癌的酪氨酸激酶通路和血管内皮生长因子受体基因在致癌过程中可能存在协同作用,导致肿瘤在结直肠中更易发生发展,选择靶向药物治疗时需考虑协同作用,以便科学精准用药。     

754例Ⅰ期-Ⅲa期可手术切除非小细胞肺癌患者EGFR和KRAS基因突变状态及其临床意义

背景与目的 表皮生长因子受体(epidermal growth factor receptor,EGFR)和KRAS基因是非小细胞肺癌(non-small cell lung cancer,NSCLC)重要的分子靶点,但目前研究主要集中在晚期NSCLC组织和血浆标本的EGFR检测,早期NSCLC组织样本中EGFR和KRAS突变特征尚不清楚.本研究将探讨Ⅰ期-Ⅲa期NSCLC EGFR和KRAS基因突变与相关临床病理特征的关系.方法 采用突变扩增系统(amplification refractory mutation system,ARMS)PCR方法检测北京协和医院病理科提供的754例Ⅰ期-Ⅲa期NSCLC组织样本的EGFR和KRAS基因突变状况,分析基因突变率及其与临床病理特征的关系.结果 EGFR和KRAS基因热点突变的突变率分别为34.5％和13.1％,其中有3例样本具有EGFR和KRAS基因的双突变.EGFR基因在女性中的突变率高于男性(39.5％vs 29.4％,P=0.076),在腺癌中的突变率(38.7％)高于鳞癌、腺鳞癌、大细胞癌(P＜0.01),但仍明显低于其他研究报道的亚裔晚期腺癌突变率(-50％).KRAS基因突变在男性中的突变率高于女性(16.6％vs 9％,P=0.048),且在腺癌中的突变率也高于其他类型,但差异不显著(P=0.268).与KRAS基因突变阳性组相比,EGFR基因突变阳性组在年龄分布上有年轻化的趋势(P=0.031,5),在性别分布上有显著性差异(P＜0.01).结论 Ⅰ期-Ⅲa期NSCLC EGFR基因突变率较晚期患者低,且EGFR和KRAS基因双突变的发生率为0.9％.     

NSCLC原发肿瘤和转移瘤中EGFR基因突变、基因扩增及KRAS基因突变的Meta分析

目的：检测NSCLC原发肿瘤和转移瘤中EGFR基因突变、基因扩增及KRAS基因突变情况,为临床靶向治疗提供更多的循证医学证据。方法：计算机文献检索中英文数据库,收集国内外公开发表的有关EG-FR-TKI靶向治疗预测性生物标记的文献研究,采用Cochrane协作网提供Review Manager 5.2软件进行Meta分析。结果：筛选文献,共11篇纳入研究。Meta分析结果显示,EGFR基因突变组、基因扩增组及KRAS基因突变组RR值分别为0.86（0.65-1.15）、0.73（0.44-1.20）及1.39（0.95-2.03）。结论：联合检测EGFR基因和KRAS基因在原发肿瘤中的突变情况,可作为EGFR-TKIs一线治疗较好的预测性生物标记。检测转移瘤中EGFR基因的扩增情况能够帮助进一步筛查哪些患者对靶向治疗更加敏感。     

肺腺癌EGFR、KRAS基因突变、ALK融合蛋白状态分析

目的 分析肺腺癌中EGFR、KRAS、ALK三种肿瘤驱动基因的突变状态及与其临床病理特征、肿瘤分期的关系.方法 85例肺腺癌EGFR,KRAS基因突变采用ARMS法检测,ALK融合蛋白用特异性抗ALK单克隆抗体(克隆号:D5F3)采取免疫组织化学法检测.结果 EGFR,KRAS,和ALK融合蛋白检测阳性率分别是62％,15％,和14％.EGFR基因突变更常见于女性.KRAS基因突变更常见于男性及有吸烟史患者.ALK融合蛋白更常见于年轻及肿瘤分期Ⅲ/Ⅳ患者.检测中发现了8例双突变病例.结论 结果 进一步证实了EGFR、KRAS基因突变与ALK融合蛋白并非完全互斥.对于肺腺癌患者进行全面的基因检测非常重要,在选择靶向治疗时更应考虑到多种变异同时存在的情况.     

晚期胃癌患者血液ctDNA水平与组织学基因检测的一致性比较

目的:比较晚期胃癌患者外周血循环肿瘤DNA（circulating tumor DNA,ctDNA）与组织学基因检测的一致性,讨论ctDNA的临床应用价值。方法:根据纳排标准最终收集30例晚期初诊初治胃癌患者的实体组织标本及血浆标本,并用二代测序(next generationg sequencing,NGS)技术分别检测68个基因在其中的表达状况。对比ctDNA与组织学检测基因的检出一致性及差异,评估其用于诊断胃癌的敏感度、特异度。并按胃癌突变基因分层进一步评估ctDNA的检出率。结果:30例患者中检出的基因突变总共138个,其中组织学标本中总共检出71个,ctDNA中总共检出67个。ctDNA对比组织学检测基因诊断胃癌的灵敏度为31.5%,特异度为63.6%,一致率为43.3%。单基因检测分析突变最多的基因前三位为TP53、PIK3CA、HER-2。其中对PIK3CA的检测,组织学和ctDNA两种方法差异有统计学意义（P＜0.05）。TP53、PIK3CA、HER-2、EGFR、KRAS在组织学中检出丰度大于1,但在ctDNA中小于1。有PIK3CA突变的患者中,共存的其他致癌基因突变位点包括KRAS 2例、BRAF 2例、EGFR 4例。有HER-2突变的患者中,共存PIK3CA突变者4例,共存KRAS突变者3例。结论:ctDNA检测虽然在晚期胃癌患者的诊断中敏感度、特异度低于组织标本基因检测,但其标本易获、接受度高,可作为基因检测的补充、备选。实体组织检出相同基因的突变丰度总体高于ctDNA。TP53、PIK3CA、HER-2、EGFR等基因在ctDNA中的检出有利于指导胃癌治疗及预后评估,尤其PIK3CA在ctDNA中高于组织中的检出率。ctDNA检测可为胃癌患者的精准靶向治疗提供依据。     

晚期非小细胞肺癌患者KRAS基因状态与一线化疗疗效关系探讨

目的 鼠类肉瘤病毒癌基因(kirsten rat sarcoma viral oncogene,KRAS)是非小细胞肺癌(non-small cell lung cancer,NSCLC)的重要驱动基因之一,KRAS基因状态在晚期NSCLC患者一线化疗疗效中的预测作用尚未明确.本研究旨在探讨晚期NSCLC患者KRAS基因状态和一线化疗疗效的关系.方法 回顾性分析郑州大学第一附属医院2014-07-10-2015-12-01收治经组织病理学确诊的205例表皮生长因子受体(epidermal growth factor receptor,EGFR)阴性的晚期NSCLC患者临床资料.随访至2015-12-31,排除随访丢失的患者,185例患者纳入本研究.分析KRAS基因状态、临床特征、化疗疗效及无疾病进展生存期(progression-free survival,PFS)之间的关系.结果 185例患者均进行了KRAS基因检测,KRAS基因突变患者44例(23.8％),野生型为141例(76.2％).KRAS基因突变类型分别为G12D(36.4％)、G12A(25.0％)、G12C(15.9％)、G12V(13.6％)、G12R(6.8％)和G13D(2.3％).全部患者均接受一线铂类为基础的化疗,客观缓解率(objective response rate,ORR)为24.3％,疾病控制率(disease control rat,DCR)为62.2％.KRAS野生型患者的DCR为63.8％,略高于突变型患者的56.8％,差异无统计学意义,x2 =0.701,P=0.477.KRAS突变患者培美曲塞化疗组中男性的ORR为52.2％,高于女性的12.5％,差异有统计学意义,x2=6.454,P=0.011;男性的DCR为82.6％,明显高于女性的31.2％,差异有统计学意义,x2=10.516,P=0.001.KRAS基因野生型患者的中位PFS为4.3个月,显著长于突变组患者的3.7个月,差异有统计学意义,x2 =21.982,P＜0.01;而KRAS各突变亚型之间的PFS相比较,差异无统计学意义,x2 =5.110,P=0.403.Cox回归多因素分析显示,KRAS基因突变是影响PFS的预后因素,HR=2.152,95％CI:1.513～3.062,P＜0.01.结论 KRAS突变是晚期NSCLC患者一线化疗PFS的负性预后因素,KRAS突变患者中男性对以培美曲塞为基础的化疗反应更好.     

非小细胞肺癌患者血清EGFR基因突变循环DNA检测

目的:探讨循环DNA测定表皮生长因子受体(epidermal growth factor receptor,EGFR)突变的可行性;旨在提供更方便、快捷、无创的分子生物检测手段,指导晚期非小细胞肺癌(non-small cell lung cancer,NSCLC)患者靶向治疗。方法:收集石河子大学医学院第一附属医院2011-09-21-2012-09-30接受靶向治疗(吉非替尼或厄洛替尼)的48例晚期NSCLC患者血清及相应石蜡组织标本DNA,采用直接测序法检测EGFR基因19和21外显子的突变情况,应用SPSS17.0软件进行统计学分析。结果:48例患者循环DNA中EGFR基因突变检出率为14.583%(7/48),且与组织DNA检测出EGFR突变类型一致,即19外显子突变型为19DelK746~A750、19DelK745~E749和19DelK745~A750;21外显子突变类型分别为21L858R和21L861Q。EGFR突变主要发生在女性及不吸烟的患者中;且EGFR基因突变型者PFS明显优于野生型患者,χ2=11.287,P=0.001。以组织DNA检测为准,循环DNA中EGFR基因突变检测的特异性为97%,并且与组织DNA检测EGFR基因突变具有一定的一致性,Kappa=0.433。结论:血清循环DNA可用于EGFR基因突变检测,为肺癌靶向治疗提供实验依据。     

疫情之下晚期肺癌的靶向治疗

在疫情期间,肿瘤患者是免疫力低下的弱势群体,面临着疾病与疫情的双重考验。那么具有敏感突变的晚期肺腺癌患者,应该如何治疗?晚期肺腺癌基因检测结果解读目前晚期肺腺癌有靶向治疗药物的基因突变包括EGFR突变、ALK融合、ROS1融合、BRAF突变、NTRK融合、C-MET扩增、C-MET14外显子跳跃突变,而KRAS突变是目前已知靶向治疗耐药的标志。     

骨髓增生异常综合征患者基因突变情况分析

目的 分析骨髓增生异常综合征(MDS)患者的基因突变情况.方法 选择2016年1月至2017年7月中国中医科学院西苑医院初诊的47例MDS患者,采用NGS 127-gene panel检测基因突变,分析基因突变与临床特征的关系.结果47例MDS患者中,31例(66.0％)检测到基因突变,涉及有临床意义的突变基因23个,检出率>5％的基因共7个,由高到低依次为U2AF1(23.4％)、SF3B1(12.8％)、ASXL1(10.6％)、TET2(8.5％)、BCOR(8.5％)、TP53(8.5％)、DNMT3A(6.4％).31例基因突变患者中,16例(51.6％)存在2个以上基因协同突变,其中12例患者的协同基因突变存在于不同基因功能组内,高于单一基因功能组内的基因协同突变(4例).IDH2-KRAS、IDH2-SRSF2、IDH2-STAG2、KRAS-SRSF2、KRAS-STAG2、RUNX1-PHF6、EZH2-ASXL1、EZH2-ZRSR2、NPM1-NRAS基因之间有共存关系(均P<0.05).JAK2、KRAS、NRAS、SH2B3四个信号通路相关的变异等位基因频率(VAF)较低,处于亚克隆地位.1例JAK2突变见于MDS-U患者;1例SH2B3基因突变见于核型预后极高危患者;2例SETBP1以及2例EZH2突变均见于修订的国际预后评分系统(IPSS-R)预后高危患者.结论 MDS患者常见突变基因为U2AF1、SF3B1、ASXL1、TET2.不同基因功能组内的基因倾向于协同突变.基因突变可用于判断MDS患者预后,作为其治疗的靶点.     

Mutations of KRAS and TP53 in a Minor Proportion of Opisthorchis Viverrini-Associated Cholangiocarcinomas in a Hamster Model.

Background/Aims KRAS oncogene and TP53 tumor suppressor gene have been known as common genesinvolving in many cancers including cholangiocarcinoma (CCC). Activation of these genes could lead touncontrolled proliferation and cancer ultimately. The aim of this study was to investigate mutation of KRASexon 1 and TP53 exon 5-8 in Opisthorchis viverrini (OV)-induced cholangiocarcinoma (CCA) in a hamster model.Methods: Twenty-seven CCAs were obtained from Syrian golden hamsters induced by OV infection and Nnitrosodimethylnitrosamine(N-NDDM) administration. The tumor tissues were processed for histopathology.Genomic DNA extracted from paraffin sections by microdissection was amplified for KRAS exon 1 and TP53exon 5-8 mutations by PCR-direct sequencing. Results Histopathologically, the tumors were classified into tubular(81.5%, 22/27), papillary (3.7%, 1/27), mucinous (3.7%, 1/27) and mixed types (11.1%, 3/27). Of the 27 CCAs,PCR-direct sequencing of KRAS showed G‡A transition at codon 37 exon 1 in one CCA sample (3.70%). Pointmutations of p53 exon 6 (G‡C transversion at codon 119 and 218 and A‡C transversion at codon 217) werefound in 3 CCA samples (11.1%). Conclusions: The results suggest that mutation of TP53 particularly at exon 6may be involved in cholangiocarcinogenesis and a novel mutation of KRAS exon 1 was firstly reported in OVinducedhamster CCA.     

西妥昔单抗联合伊立替康为主方案治疗转移性结直肠癌

目的：观察西妥昔单抗联合伊立替康治疗晚期结直肠癌的疗效、安全性及KRAS基因突变与疗效的相关性。方法：对经西妥昔单抗联合伊立替康为主方案治疗且可评价疗效的15例晚期结直肠癌患者进行疗效分析,并对其中12例患者进行KRAS基因测定,分析KRAS基因突变与疗效的相关性。结果：（1）疗效分析：15例患者治疗后取得部分缓解4例,病情稳定7例,疾病进展4例,客观有效率26.7％,疾病控制率73.3％,中位疾病进展时间16周。主要的不良反应是痤疮样皮疹、腹泻和骨髓抑制。痤疮样皮疹发生率为80％（12 /15）,腹泻发生率为46.7％（7/15）,骨髓抑制发生率为60％（9/15）。在出现痤疮样皮疹的12例患者中,客观有效率为33.3％,疾病控制率为83.3％。（2）KRAS基因突变与疗效的相关性：12例患者进行KRAS基因检测中,KRAS基因野生型的患者7例,客观有效率为28.6％,疾病控制率为85.7％,中位疾病进展时间18周;KRAS基因突变的患者5例,疗效为部分缓解1例,客观有效率为20％,疾病控制率为60％,中位疾病进展时间为12周。因纳入病例数较少,两者比较差异无统计学意义。结论：西妥昔单抗联合CPT-11为主方案对晚期结直肠癌患者有效。除痤疮样皮疹外,不良反应无明显增加。对于出现痤疮样皮疹患者提示获益可能。对于KRAS基因野生型的患者,预示西妥昔单抗联合CPT-11能获得良好的疗效,对于KRAS基因突变型的患者,预示西妥昔单抗联合CPT-11未能增加疗效。     

High Frequency of KRAS Codon 146 and FBXW7 Mutations in Thai Patients with Stage II-III Colon Cancer

Background: KRAS, NRAS, and BRAF gene mutations are the most clinically relevant and frequently reported incolorectal cancer (CRC). Although data on these genes are frequently reported in several counties, data specific to thesegenes among Thai population are scarce. The aim of this study was to investigate and identify molecular alterationsassociated with colon cancer in Thai population, and to determine the impact of these genetic aberrations on clinicaloutcome. Methods: DNA from 108 archived formalin-fixed, paraffin-embedded (FFPE) tissue samples that histologicallyconfirmed adenocarcinoma of stage II-III colon cancer between 2010 and 2012 at Siriraj Hospital (Bangkok, Thailand)were extracted. Gene mutational analysis was performed by next-generation sequencing (NGS) using an OncomineSolid Tumor DNA kit (Thermo Fisher Scientific, Inc., Waltham, MA, USA). Results: A total of 22 somatic genemutations were detected. The mutation frequency observed in KRAS, NRAS, BRAF, PIK3CA, and FBXW7 mutationswas 47.2%, 1.9%, 1.9%, 12%, and 14.8%, respectively. KRAS mutation codon 12, 13, 59, 61, 117, and 146 mutationswere identified in 29.6%, 8.3%, 1.8%, 0.9%, 0.0%, and 8.3%, respectively. KRAS Exon 4 had better DFS comparedwith Exon 2 and 3. Conclusions: This study is the first to comprehensively report hotspot mutations using NGS in Thaicolon cancer patients. The most commonly identified gene mutation frequencies among Thai patients (KRAS, NRAS,BRAF, TP53, and PIK3CA) were similar to the gene mutation frequencies reported in Western population, except forsubgroup of KRAS codon 146 and FBXW7 mutations that had a slightly higher frequency.     

二代测序在家族遗传性高危胃肠肿瘤筛查中的应用

  目的  探索二代测序技术对家族遗传性高危胃肠肿瘤患者进行遗传筛查的意义及高危因素在筛选患者中的价值。  方法  选取2016年3月至2016年4月收治于北京大学肿瘤医院的322例结直肠癌及胃癌患者,筛选出25例遗传性胃肠肿瘤高危患者,运用二代测序技术对患者的外周血白细胞DNA进行42个遗传性肿瘤综合征相关基因的胚系检测。  结果  24%（6/25）患者检测出遗传性肿瘤相关基因的病理性胚系突变,其中50%（3/6）患者肿瘤组织的免疫组织化学检测表现为错配修复蛋白表达缺失,83%（5/6）患者发病年龄≤50岁且具有恶性肿瘤家族史。发生胚系突变的6例遗传性肿瘤相关基因分别为MYH基因错义突变1例,APC基因缺失突变1例和遗传性非息肉病性结直肠癌（hereditary nonpolyposis colorectal cancer,HNPCC）相关基因的突变4例（包括MLH1、MLH3、TGFBR2的错义突变和MSH6的无义突变各1例）,且提供了MLH3的胚系致病突变的家系验证。  结论  通过二代测序技术对本研究入组的25例患者进行家族遗传性肿瘤综合征的筛查,检测出遗传性肿瘤相关基因的胚系致病突变6例,提示运用二代测序技术对家族遗传性高危消化道肿瘤患者进行遗传筛查具有提高检测阳性率的临床应用价值。      

DNA修复基因及其TP53共突变在肺腺癌免疫治疗疗效预测中的价值

目的 基于二代测序技术,探索DNA修复基因(DRGs)对肺腺癌免疫治疗疗效的预测价值.方法 选取癌症基因组图谱中肺腺癌两个独立数据集(分别为测试集和验证集).测试集中,依据肿瘤突变负荷评分15为阈值,分为低突变负荷组和高突变负荷组,分析不同肿瘤突变负荷与肺腺癌总生存的关系,并以KRAS/TP53共突变作为标准参照,分析...     

Impact of GSTT1, GSTM1, GSTP1 and NAT2 genotypes on KRAS2 and TP53 gene mutations in colorectal cancer

Which carcinogens are of influence in the development of human colorectal cancers remains a question; one answer could be the finding that specific polymorphisms in xenobiotic metabolizing enzymes are related to particular mutations in cancer genes. KRAS2 and TP53 gene mutations as well as genotypes for GSTM1, GSTP1, GSTT1 and NAT2 were determined in an exploratory series of 165 stable colorectal cancers. Mutations in KRAS2 and TP53 were found in 34% and 57.5% of cases, respectively. The KRAS2 mutation frequency was significantly lower in patients with a GSTT1 null genotype than in those with a GSTT1 non-null genotype (18% vs. 38%, p = 0.03). The overall risk of KRAS2 mutation for patients with distal colorectal cancer and GSTT1 null genotype was 0.3 (95% CI 0.1-0.9) compared to patients with distal colorectal cancer and non-null GSTT1 genotype. The overall risk of KRAS2 mutation was similarly reduced (OR = 0.4, 95% CI 0.2-0.9) for patients with distal colorectal cancer and GSTP1 mutated genotypes compared to patients with distal colorectal cancer and wild-type genotype. Patients with GSTP1 wild-type genotype appeared to be at significantly lower risk for TP53 mutation compared to patients with mutated genotypes (p = 0.023). Our results suggest that GSTT1 and GSTP1 could play a role in the occurrence of KRAS2 and TP53 mutations in colorectal cancer and generate a hypothesis on the dietary factors that could be incriminated.     

TP53 and KRAS2 mutations in plasma DNA of healthy subjects and subsequent cancer occurrence: a prospective study

In cancer patients, plasma often contains mutant DNA released by cancer cells. We have assessed the significance of plasma DNA mutations for subsequent cancer development in healthy subjects in a large longitudinal prospective study. The European Prospective Investigation into Cancer and Nutrition study was analyzed with a nested case-control design. Cases were nonsmokers or ex-smokers for >10 years and newly diagnosed with lung, bladder, or upper aerodigestive tract cancers or leukemia accrued after a median follow-up of 6.3 years. Controls were matched 2:1 for follow-up, age, sex, area of recruitment, and smoking status. KRAS2 mutations were detected by mutant-enriched PCR and sequencing (n = 1,098). TP53 mutations were detected by denaturing high-performance liquid chromatography, temporal temperature gradient electrophoresis, and sequencing (n = 550). KRAS2 or TP53 mutations were detected in 13 of 1,098 (1.2%) and 20 of 550 (3.6%) subjects, respectively, 16 of whom developed cancer on average after 18.3 months of follow-up. Among 137 subjects who developed bladder cancer, 5 had KRAS2 mutations [odds ratio (OR), 4.25; 95% confidence interval (95% CI), 1.27-14.15] and 7 had TP53 mutations (OR, 1.81; 95% CI, 0.66-4.97). There was a nonsignificant trend for association between TP53 mutations and bulky adducts in lymphocyte DNA (OR, 2.78; 95% CI, 0.64-12.17). This is the first report of TP53 or KRAS2 mutations in the plasma of healthy subjects in a prospective study, suggesting that KRAS2 mutation is detectable ahead of bladder cancer diagnosis. TP53 mutation may be associated with environmental exposures. These observations have implications for monitoring early steps of carcinogenesis.     

BRAF,KRAS and PIK3CA Mutation and Sensitivity to Trastuzumab in Breast Cancer Cell Line Model

Studies show that approximately 20% of all breast cancer patients have a breast tumor that tests positive for Human Epidermal Growth Factor Receptor 2, otherwise known as the HER2 gene. As such, treatments for breast cancer usually include drugs that target HER2. The drug Trastuzumab is a recombinant antibody that has been approved by the FDA for the treatment of these HER2 positive breast cancers. However, researchers have found that mutations in associated genes, PIK3CA and KRAS, can cause the tumor to become resistant to Trastuzumab. The purpose of this article is to evaluate the sensitivity of the cancer cell lines to the drug Trastuzumab and investigate how this sensitivity is compromised by the PIK3CA, KRAS and BRAF gene mutations. Trastuzumab responsiveness was evaluated in breast cancer cell lines by treating the lines with an optimal concentration of the drug followed by a proliferation assay of the cell lines in the presence of monoclonal antibodies. We determined the optimum concentration of Trastuzumab to be 7 μg/well. The BRAF and KRAS mutated cell line, MDA-MB-231, showed the least sensitivity after being treated with trastuzumab when compared to the sensitivity of the PIK3CA mutated cell lines, MCF-7 and MDA-MB-361, and the KRAS/ BRAF/ PIK3CA cell line, MDA-MB-453. Clinical observations show that mutations in BRAF and KRAS genes in breast cancer cells do lower the responsiveness of Trastuzumab drug treatments.