Cancer is the one of the deadliest diseases and takes the lives of millions of people every year across the world. Due to disease heterogeneity and multi-factorial reasons, traditional treatment such as radiation therapy, immunotherapy, or chemotherapy are effective only among a small population of the patients. Tumors can have different fundamental genetic causes and protein expressions that differ from one patient to another. This variability among individual lends itself to the field of precision and personalized medicine. Following the completion of human genome sequencing, significant progress has been observed in the characterization of human epigenome, proteome, and metabolome. Pharmacogenetics and pharmacogenomics use this sequence to study the genetic causes of individual variations in drug response and the simultaneous impact of change in genome that decide the patient's response to drug respectively. On summation, identify the subpopulation of patient and provide them tailored therapy thus increasing the effectiveness of treatment. All these evolved the field of precision or personalized medicine that plays a crucial role in cancer prevention, prognosis, diagnosis, and therapeutics. These tailored therapies are characterized by increased efficiency and reduced toxicity. Not all cancers have genetic variability; some are also influenced by polymorphism of gene encoding enzymes that play an important role in pharmacokinetics of drug. The discoveries of cancer predisposition genes allow diagnosis of a patient at risk of cancer development and let them make the decision on précised individual risk modification characteristic. The use of CYP2D6 genotyping for breast cancer, mutation in KRAS in colorectal cancer, genomic variation in EGFR in small lung cancer, melanoma are some of the examples of importance of cancer predisposition genes. In recent times, distinct molecular subtypes of cancers have been identified with requirement of different treatment for each subtype. Precision medicine shifts the trend from reaction to prevention and forestalls disease progression.

Self-renewal is the most important property of stem cells. Parallel to this, cancer stem cells (CSCs) have an indefinite proliferative ability that drives tumorigenesis. The conventional treatment of cancer includes chemotherapy, radiotherapy, and surgery, which decreases the tumour size. Contrary, targeted therapy against CSCs initially does not shrink the tumour but ultimately causes tumour degeneration. Nanobiotechnology, RNA interference, microRNA are emerging fields with a vital role in targeted therapy against CSCs. The non-protein encoding microRNAs has a major role in cancer treatment since they regulate gene expression during post-transcription. RNAi technology can silence the gene of interest with potency and specificity inhibiting tumour growth. In nanoparticles-based RNA interference, nanocarriers protect RNAi molecules from immune recognition and enzymatic degradation. The cancer cell gene expression profiling using next-generation sequencing helps in understanding the underlying cancer cell mechanisms. The current chapter deals with novel concepts in the treatment of cancer.