Recent progress in nanotechnology has paved the way for development of new tools for cancer imaging and treatment. Failure of early diagnosis is one of the major hurdles in cancer treatment. In addition, conventional treatment approaches suffer from problems of non-specific bio distribution of chemotherapeutic agent, low aqueous solubility, poor bioavailability, narrow therapeutic window, and rapid clearance. Nanotechnology addresses many of the aforementioned limitations and provides scope for early diagnosis, tumor-targeted delivery via passive or active targeting mechanisms, personalized treatment utilizing nanotheranostics, controlled drug release, and co-delivery of multiple therapeutic agents. This chapter summarizes various merits of nanotechnology with emphasis on different types of nanocarriers that are presently being used for drug delivery and imaging. As per these studies, the fruition of nanotechnology may make the disease curable by early diagnosis and specific drug delivery.
TopIntroduction
Cancer is one of the most dreaded diseases characterized by abnormal growth of cell with metastatic potential. As per World Health Organization (WHO) report around 7.8 million people die of this malignant disease every year, making it the second leading cause of death globally. There are around hundred different types of cancers of which, breast, colorectal, cervix, lung and stomach cancer are the most common among women, while lung, colorectal, prostate, stomach and liver cancer are the most common types in men. For over half a century cancer has been in forefront of biomedical research entailing great progress in fundamental cancer biology, however, little has been translated into clinics. This discrepancy is invariably due to cancer heterogeneity.
There are several challenges in cancer treatment, one of them being diagnosis. Despite technical advances in diagnostic radiology, early detection of neoplastic lesions remains an elusive task. In majority of the cases, tumor is detected only after it has metastasized, leaving grim chances of treatment and subsequent survival. Data from Cancer Research UK, suggests that early diagnosis results in three times higher cancer survival rate. Thus, strategies to improve diagnosis can have discernible impact on cancer morbidity and mortality.
Following diagnosis, the next gigantic challenge for cancer therapy is identification of ideal regime for elimination of cancerous cells. Oncologists have primarily depended on three treatment options viz. surgical excision, irradiation and chemotherapy. While surgery and irradiation are predominantly used for local and non-metastatic cancer, chemotherapy is the major therapeutic approach for both localized and metastatic cancer (Chidambaram, Manavalan, & Kathiresan, 2011). Chemotherapy is administration of single or multiple cytotoxic drugs to inhibit growth and division of malignant cells. Different types of chemotherapeutic agents being used are alkylating agents, neoplastic antibiotics (doxorubicin, daunorubicin, etc.), plant alkaloids (vincristine, vinblastine, paclitaxel, etc.), antimetabolites, and other miscellaneous antitumor agents. The principle idea behind using these cytotoxic agents is that they have most deleterious effect on rapidly proliferating cells. However, apart from cancer cells there are other rapidly dividing cells in the body like hair follicles, bone marrow and intestinal epithelial cells. So, these agents also have severe side effects on these tissues. This nonspecific bio distribution of existing therapeutic agents is major concern in cancer treatment. Besides, low solubility, poor bioavailability, inconsistent stability, inability to penetrate tumor cells, narrow therapeutic window, development of multi drug resistance and rapid clearance by reticuloendothelial cells are other bottlenecks in conventional chemotherapy (D. Singh, Minz, & Sahoo, 2017; Steichen, Caldorera-Moore, & Peppas, 2013) .Thus, there is an extensive need for development of new strategies which can overcome above mentioned limitations and specifically target cancer cells, thereby reducing toxicity to normal tissues.