Choudhury Partha, Gupta Manoj
Department of Nuclear Medicine, Rajiv Gandhi Cancer Institute & Research Centre, Delhi, India.
Curr Radiopharm. 2017 Nov 10;10(3):166-170. doi: 10.2174/1874471010666170728094008.
There are many challenges in the execution of targeted therapy in cancer due to tumor heterogeneity between individuals. In case of solid tumors this is one of the reasons as to why genomic analysis from single tumor biopsy specimens underestimate the mutational burdens in such heterogeneous tumors thus contributing to treatment failure and drug resistance. Molecular characteristics redefine tumor classification for molecular targeted therapies ensuring the best patient specific therapies with better specificity and cost effective ratio. Functional imaging like Positron Emission Tomography & Computed Tomography (PET-CT) with 18-F Fluorodeoxyglucose (FDG) has been extensively used in oncology to assess the glucose metabolism in tumor cells since long. It has been further redefined to use other radiopharmaceutical targets capable of tumor characterization, microenvironment, angiogenesis, proliferation, apoptosis, receptor expression and few others. Among these the receptor expression in tumors have been studied in detail and specific imaging probes have been developed for imaging with either Single Photon Emission Computed Tomography (SPECT-CT) or PET-CT. Combination of these diagnostic tool with the same vector has permitted an easy switch from diagnosis to therapy using a therapeutic radionuclide when such expression is documented. Thus in Nuclear Medicine the concept of Theranostics have been utilized with ease and successfully implemented the theranostic concept and has become a valid example of personalized and precision medicine. Imaging and therapy of thyroid cancer, neuroendocrine tumors and castration resistant prostate cancer are current examples of this concept.
Molecular imaging has high potential to link target identification with therapy and thus to personalize it. It also has a very high potential for in-vivo tissue characterization, to improve prediction, prognostication, road map for biopsy and monitoring of therapy.
由于个体间肿瘤的异质性，癌症靶向治疗的实施面临诸多挑战。对于实体瘤而言，这是导致从单肿瘤活检标本进行基因组分析会低估此类异质性肿瘤的突变负担，进而导致治疗失败和耐药的原因之一。分子特征重新定义了分子靶向治疗的肿瘤分类，确保为患者提供具有更好特异性和性价比的最佳个体化治疗。正电子发射断层扫描与计算机断层扫描（PET-CT）结合18氟脱氧葡萄糖（FDG）等功能成像技术长期以来一直在肿瘤学中广泛用于评估肿瘤细胞的葡萄糖代谢。它已被进一步重新定义，以使用能够对肿瘤特征、微环境、血管生成、增殖、凋亡、受体表达等进行表征的其他放射性药物靶点。其中，肿瘤中的受体表达已得到详细研究，并开发了用于单光子发射计算机断层扫描（SPECT-CT）或PET-CT成像的特异性成像探针。当记录到这种表达时，使用相同载体将这些诊断工具与治疗性放射性核素相结合，就可以轻松地从诊断转向治疗。因此，在核医学中，治疗诊断学的概念已被轻松应用并成功实施，成为个性化和精准医学的一个有效范例。甲状腺癌、神经内分泌肿瘤和去势抵抗性前列腺癌的成像与治疗就是这一概念的当前实例。
分子成像具有将靶点识别与治疗联系起来从而实现个性化治疗的巨大潜力。它在体内组织表征、改善预测、预后、活检路线图制定及治疗监测方面也具有很高的潜力。
