由于前期国内外不同单位的多项不良临床实践结果,以及高级别循证医学证据的缺乏,单独实施放疗、化疗或放疗联合化疗的方案,对胆道恶性肿瘤的辅助治疗价值未得到广泛共识 [1] 。对于术后辅助性放疗在胆道肿瘤临床价值的研究显示,已实施规则性手术切除的胆囊癌患者术后进行术区范围放疗并不能得到生存获益 [2] 。
随着治疗技术的进步,近期陆续有放疗对肝内胆管癌的治疗价值的正面研究结果报道 [3,4] 。对无法手术治疗的肝内胆管癌实施质子放疗的Ⅱ期临床研究显示,治疗2年内肿瘤局部控制率可达到95%的乐观数据 [5] 。
对放疗联合卡培他滨或吉西他滨化疗方案在肝外胆管癌和胆囊癌Ⅱ期治疗价值的临床研究也有积极的数据报道 [6] 。
在对直肠癌、肺癌等进行放疗的研究发现, KRAS 突变型肿瘤较野生型的放疗效果不佳,这一临床发现提示 KRAS 基因突变可能是肿瘤耐受放射治疗的机制 [7] 。因此,依据胆道恶性肿瘤的 KRAS 基因突变的情况进行个体化放疗研究可能是一个方向。此外,基于部分肿瘤放疗后可由对免疫治疗低应答转为高应答的研究和临床实践 [8,9] ,胆道肿瘤放疗联合程序性死亡蛋白-1(PD-1)抑制剂等免疫治疗也已成为临床探讨的方向。
由于受限于胆道恶性肿瘤发病率较低但恶性程度高、研究病例较少的临床现实因素,对胆道恶性肿瘤化疗标准方案的循证医学研究历史并不长久,氟嘧啶(5-FU/卡培他滨)、吉西他滨和铂类药物是研究的焦点 [10] 。目前,胆道恶性肿瘤还缺乏有效的生物标志物来预测对化疗方案的响应情况,所谓的胆道恶性肿瘤“一线化疗方案”,主要是指吉西他滨单药或联合铂类的方案 [11-15] 。此外,以S1为基础的联合化疗方案,也得到相关研究报道的推荐 [10,16-19] 。
但对于实施吉西他滨方案辅助治疗胆管癌患者的价值,尚待更多的循证医学证据支持。2018年的一项研究发现,基于Cochrane系统肝胆组对照试验登记资料、Central、Medline、EMBASE、Lilac、科学引文索引、会议记录引文索引及文献报道等(截至2017年6月)的数据,采用Cochrane系统的标准分析方法(预先设定偏倚风险域的定义;评估纳入试验的偏倚风险;结合研究结果的临床应用等级等),对吉西他滨单药、或以吉西他滨为基础的化疗方案,纳入7个治疗成人进展期胆管癌的临床随机试验项目(共600名受试者),由于研究的循证医学证据确定度低(均存在偏倚风险;缺乏充分的信息;可能存在的出版期刊的文章发表偏见等,导致研究质量较低等),尚无法准确评价吉西他滨单药或联合化疗放疗对研究人群死亡率的影响,或得出治疗是否使患者获益的结论 [20] 。
卡培他滨对胆管癌化疗的临床价值,近年来逐渐引起关注。Primrose JN等在美国临床肿瘤学会(American Society of Clinical Oncology,ASCO)2017年会报道了卡培他滨术后辅助治疗胆管癌有效性和安全性的Ⅲ期临床试验(BILCAP研究),研究人群包括肝内胆管癌、肝门部胆管癌、肿瘤侵犯至肌层的胆囊癌(T1b期以上)和远端胆管癌,涵盖肿瘤根治性切除(R0)及肉眼完整切除者(R1)共447例受试者(英国地区胆管癌人群)。研究病例随机分配入观察组和卡培他滨治疗组(共24周、8个疗程),随访持续2年以上,比较两组人群的总生存(overall survival,OS)情况。研究结果表明,术后卡培他滨辅助化疗方案可以改善可切除性胆管癌患者预后,术后总生存期由对照观察组的36.4个月延至卡培他滨化疗组的51.1个月(虽然两组间差异尚未达到统计学意义),并证明研究周期内患者可以耐受卡培他滨的不良反应 [21] 。对受试者进行分类统计发现,除肝门部胆管癌组术后卡培他滨辅助化疗未体现治疗获益外,肝内胆管癌、胆囊癌、远端胆管癌受试人群研究期内生存期均优于对照组人群 [22] 。
新近韩国学者报道的一项开放、随机、非劣效性研究的Ⅲ期试验,随机选择转移性晚期胆管癌患者接受Gemox方案(第1天和第8天为吉西他滨1 000mg/m 2 ,第1天为奥沙利铂100mg/m 2 )或Xelox方案(第1~14天为卡西他滨1 000mg/m 2 ,第1天为奥沙利铂130mg/m 2 )作为一线化疗方案(每3周为1疗程、共8疗程)。对比Xelox方案和Gemox方案治疗6个月的疾病无进展生存(progression-free-survival,PFS)方面,Xelox方案疗效不劣于Gemox方案。Gemox方案组的中位PFS为5.3个月,Xelox方案组为5.8个月;Gemox方案组6个月时达到PFS的受试者比例为44.5%,Xelox方案组为46.7% [23] 。据此研究者认为,Xelox方案亦有望成为胆管癌一线化疗方案。
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