【原】手持笔式设备可在外科医生指尖实时做出癌症无创诊断

　　虽然外科医生的目标是彻底清除癌症，但是在有限的手术期间实现阴性切缘存在挑战。手术后如果有癌症组织残留，可使患者肿瘤复发风险增加，然而大多数病理科实验室需要几天时间才能对手术获取标本是否仍然含有肿瘤细胞做出评估。

病理检查首先需要将切下的病变组织器官作一系列技术处理，包括固定、取材、脱水、浸蜡、包埋、切片和染色等，一般需花费24小时方可完成全部制片过程，然后由病理医生用显微镜观察，并做出诊断。这种检查方法称为常规石蜡切片，是病理检查中最常用的方法。但是，这种方法从外科医生将病变组织切下，到做出病理诊断，前后通常需要3天的时间。有时外科医生希望在手术过程中马上了解病变的性质，以便及时确定手术范围，并做出相应的处理，就要求病理医生在手术过程中做出病理诊断，此时就必须快速切片诊断，快速冰冻切片是目前应用的最广泛的方法。快速冰冻切片是用于手术中病理诊断的一种方法，病理医生在收到手术标本后约l5分钟之内做出诊断，马上电话告诉手术医生，以便迅速作出下一步治疗决策。病理诊断的正确与否直接关系到手术台上处理患者的下一个步骤，如乳腺肿块切除后的冰冻报告是良性的纤维腺瘤，则可宣告手术结束；如冰冻报告是乳腺癌，就需要进一步扩大手术范围，切除整个乳房及腋窝淋巴结；肢体的恶性肿瘤如骨肉瘤，通常需截肢。冰冻切片病理诊断对手术治疗有重大帮助和指导意义，诊断要力求正确、迅速和可靠。然而，快速冰冻切片要在如此之短的时间内做出诊断，难度相当高，取材有局限性，制作切片的质量也不如常规石蜡切片高。因此，冰冻切片的确诊率比常规切片低，有一定的延迟诊断率和误诊率。目前，冰冻切片诊断尚不能广泛应用，即使选择性应用，事后仍需用常规石蜡切片对照和存档。

　　2017年9月6日，美国科学促进会《科学》旗下《转化医学》在线发表奥斯汀德克萨斯大学、贝勒医学院、德克萨斯大学MD安德森癌症中心的研究报告，研发出一种手持笔式探头（质谱笔）能在10秒钟内以自动化无创方式区别肿瘤组织和健康组织，从而能快速地诊断癌症，帮助外科医生在手术期间清除所有癌症。

　　用于组织病理学诊断的传统方法通常需要花费大量人力和时间，并且可能延误诊断和治疗决策。为了寻找能实时进行更有效的组织良恶性分析方法，作者发明了一种手持笔式探头（质谱笔），能用极少量水（10微升，大约一滴水的五分之一大小）与组织表面轻柔物理接触3秒以有效提取生物分子，随后通过一根柔性管将标本自动转移至质谱分析仪，计算标本所含蛋白质、脂质、代谢产物的分子质量进行诊断。该研究对253例患者的乳腺、肺、甲状腺、卵巢、健康组织标本进行分析后，制定了快速识别组织的分子谱，识别癌症的敏感度、特异度、准确度分别高达96.4%、96.2%、96.3%。最后，质谱笔还能够可靠地在肿瘤小鼠活体手术期间诊断癌症，且不会对健康组织造成任何伤害。与现有的质谱分析工具（需要特异标记、造影成像、苛性溶剂、加压气体或高电压）不同，质谱笔仅用水采集需要分析的分子。此外，质谱笔尖是3D打印的聚二甲基硅氧烷（二甲基硅油），安全且有生物相容性。分析更大的标本组可使质谱笔更为精准，能对来自范围更广的不同类型组织肿瘤进行诊断。

　　因此，该研究结果表明，质谱笔（MasSpec Pen）可被作为临床和术中技术用于体外和体内癌症诊断。

Sci Transl Med. 2017 Sep 6;9(405):eaan3968.

Nondestructive tissue analysis for ex vivo and in vivo cancer diagnosis using a handheld mass spectrometry system.

Jialing Zhang, John Rector, John Q. Lin, Jonathan H. Young, Marta Sans, Nitesh Katta, Noah Giese, Wendong Yu, Chandandeep Nagi, James Suliburk, Jinsong Liu, Alena Bensussan, Rachel J. DeHoog, Kyana Y. Garza, Benjamin Ludolph, Anna G. Sorace, Anum Syed, Aydin Zahedivash, Thomas E. Milner, Livia S. Eberlin.

University of Texas at Austin, Austin, TX, USA; Baylor College of Medicine, Houston, TX, USA; University of Texas MD Anderson Cancer Center, Houston, TX, USA.

Is the pen mightier than the scalpel?

Although a surgeon's goal is to remove cancer in its entirety during excision surgery, achieving negative margins (absence of cancer cells at the outer edge of the excised tumor specimen) can be challenging. To facilitate intraoperative diagnosis, Zhang et al. developed a handheld pen-like device that rapidly identifies the molecular profile of tissues using a small volume water droplet and mass spectrometry analysis. After 3 s of gentle physical contact with a tissue surface, the water droplet is transported to a mass spectrometer, which characterizes diagnostic proteins, lipids, and metabolites. The pen could be used to rapidly distinguish tumor from healthy tissue during surgery in mice, without requiring specific labeling or imaging and without evidence of tissue destruction.

Conventional methods for histopathologic tissue diagnosis are labor- and time-intensive and can delay decision-making during diagnostic and therapeutic procedures. We report the development of an automated and biocompatible handheld mass spectrometry device for rapid and nondestructive diagnosis of human cancer tissues. The device, named MasSpec Pen, enables controlled and automated delivery of a discrete water droplet to a tissue surface for efficient extraction of biomolecules. We used the MasSpec Pen for ex vivo molecular analysis of 20 human cancer thin tissue sections and 253 human patient tissue samples including normal and cancerous tissues from breast, lung, thyroid, and ovary. The mass spectra obtained presented rich molecular profiles characterized by a variety of potential cancer biomarkers identified as metabolites, lipids, and proteins. Statistical classifiers built from the histologically validated molecular database allowed cancer prediction with high sensitivity (96.4%), specificity (96.2%), and overall accuracy (96.3%), as well as prediction of benign and malignant thyroid tumors and different histologic subtypes of lung cancer. Notably, our classifier allowed accurate diagnosis of cancer in marginal tumor regions presenting mixed histologic composition. Last, we demonstrate that the MasSpec Pen is suited for in vivo cancer diagnosis during surgery performed in tumor-bearing mouse models, without causing any observable tissue harm or stress to the animal. Our results provide evidence that the MasSpec Pen could potentially be used as a clinical and intraoperative technology for ex vivo and in vivo cancer diagnosis.

DOI: 10.1126/scitranslmed.aan3968