Emerging Roles of Gold Nanoparticles in Lung Cancer Diagnosis and Imaging: A Promising yet Underexplored Frontier.

Cancer is known to be a major cause of death worldwide, with lung cancer responsible for the maximum number of deaths. There is an urgent need for early and effective diagnosis of lung cancer to improve the overall survival rate, which is extremely low to date. Studies have shown that 57% of lung cancers are detected only after metastasis of the tumor. Economic restraints in hospitals are resulting in decreased early diagnosis of lung cancer and an increase in aggressive, incurable grades. Traditional imaging modalities like ultrasound, x-ray, CT, and MRI scans are often unable to precisely locate the extent of metastasis of lung cancer, paving the way for better, more sophisticated diagnostic tools. Nuclear medicine techniques help in better understanding of the metabolic extent of cancer cells using radioactive isotopes. PET/SPECT scans help provide more precise grading and better understanding of tumor morphology. However, the lack of distinction between inflammatory and malignant lesions remains a diagnostic challenge. Gold nanoparticles (GNPs) have been studied as effective contrast agents, enhancing the diagnostic efficiency of lung cancer. Formulation and tagging of GNPs have improved efficacy and biodistribution of cancer drugs; however, no such gold nanoformulation is available for diagnosis to date. The use of different shapes of GNPs functionalized with specific lung cancer biomarkers can potentially increase the specificity of lung tumor diagnosis. In this review, we address the lacunae and provide a strategic roadmap for the effective development of GNP-based diagnostics, from benchtop to high-fidelity biomaterials with clinical applications for efficient lung cancer management.