A practical molecular assay to predict survival in resected non-squamous, non-small-cell lung cancer: development and international validation studies

Summary
Background The frequent recurrence of early-stage non-small-cell lung cancer (NSCLC) is generally attributable to metastatic disease undetected at complete resection. Management of such patients depends on prognostic staging to identify the individuals most likely to have occult disease. We aimed to develop and validate a practical, reliable assay that improves risk stratifi cation compared with conventional staging.
Methods A 14-gene expression assay that uses quantitative PCR, runs on formalin-fi xed paraffi n-embedded tissue samples, and diff erentiates patients with heterogeneous statistical prognoses was developed in a cohort of 361 patients with non-squamous NSCLC resected at the University of California, San Francisco. The assay was then independently validated by the Kaiser Permanente Division of Research in a masked cohort of 433 patients with stage I nonsquamous NSCLC resected at Kaiser Permanente Northern California hospitals, and on a cohort of 1006 patients with stage I–III non-squamous NSCLC resected in several leading Chinese cancer centres that are part of the China Clinical Trials Consortium (CCTC).
Findings Kaplan-Meier analysis of the Kaiser validation cohort showed 5 year overall survival of 71·4% (95% CI 60·5–80·0) in low-risk, 58·3% (48·9–66·6) in intermediate-risk, and 49·2% (42·2–55·8) in high-risk patients
(ptrend=0·0003). Similar analysis of the CCTC cohort indicated 5 year overall survivals of 74·1% (66·0–80·6) in lowrisk, 57·4% (48·3–65·5) in intermediate-risk, and 44·6% (40·2–48·9) in high-risk patients (ptrend<0·0001). Multivariate analysis in both cohorts indicated that no standard clinical risk factors could account for, or provide, the prognostic information derived from tumour gene expression. The assay improved prognostic accuracy beyond National Comprehensive Cancer Network criteria for stage I high-risk tumours (p<0·0001), and diff erentiated low-risk, intermediate-risk, and high-risk patients within all disease stages.
Interpretation Our practical, quantitative-PCR-based assay reliably identifi ed patients with early-stage non-squamous NSCLC at high risk for mortality after surgical resection.

肺癌是中美两国以及全球导致癌病死亡的最常见原因，治疗这种疾病的挑战之一是病因往往在早期不易被发现。早期阶段通常没有症状，但却是治疗最有效的阶段。一个以加州大学旧金山分校（UCSF）科学家为首的国际研究组所开展的在肺癌分子遗传学领域的最大的两项临床研究显示，分子检测可以比传统方法更准确地预测早期肺癌所导致死亡的可能性，这项研究结果最终会有助于提高每年数以十万计的患者的生存几率。近日出版的医学期刊《柳叶刀》（The Lancet）上的研究报道了这一测算14个基因在癌组织中的活性的检测如何提高预后判断的准确性，从而有助于指导对最常见的肺癌形式--非鳞状非小细胞肺癌的患者的治疗。

该分子检测是以加州大学旧金山分校最初开发的技术为基础，其技术平台采用的是定量PCR标准实验室技术。分析程序是从一块石蜡包埋的病人癌组织样本开始的，然后确定14个特异基因的活性水平并与正常肺组织中的水平相比。这组基因中的11个基因是与肺肿瘤生物学有关的，而其他三个基因是用来标准化这些癌症基因检测的常见基因。研究人员分析了加州大学旧金山分校医学中心的361例肺癌组织样本后，开发出一个计算死亡风险的算法，而这些病人都是一种常见的称为非鳞状非小细胞肺癌的患者并接受了手术治疗的。该算法把这14个基因的活性水平与这些病人的临床结果对应起来。

为证实方法的有效性，研究人员景进行了两个独立的临床试验：一个是凯萨恒健研究所采用盲测的方法分析了433名北加州Ⅰ期肺癌患者组织样本；以及另一个由中国临床试验集团对中国1,006名Ⅰ-Ⅲ期肺癌患者的分析。这两个更大组群的临床试验结果均显示，该算法都能够非常准确地区分出死亡风险的高、中、低程度。凯萨恒健研究所的盲测显示低风险患者5年生存期为71.4%（95% CI 60.5-80.0），中等风险患者为58.3%（95% CI48.9-66.6），高风险患者为49.2%（95% CI42.2-55.8），p=0.0003。同样，中国临床试验集团的实验结果显示低风险患者5年生存期为74.1%（95% CI 66.0-80.6），中等风险患者为57.4%（95% CI48.3-65.5），高风险患者为44.6%（95% CI40.2-48.9），p＜0.0001。两群体的多元分析表明无标准的临床风险因素能提供肿瘤基因表达方面的信息。本分析方法相较传统方法，改善了预后的精确度。

该新的分子检测能够更好地识别手术后的早期死亡高危患者，因此可以成为考虑采用早期化疗的更有效的指南。