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Sensitivity to radiation and chemotherapy can be influenced by factors extrinsic to the cancer cell. For example, severely hypoxic cells require 2-3 times the radiation dose as do well-oxygenated cells to achieve similar cell killing. Apart from the tumor cells, neighboring cells such as endothelial cells may influence radiosensitivity. Irradiation can lead to expression of molecules that may increase radio/chemoresistance, for example vascular endothelial growth factor (VEGF), a secreted protein that regulates angiogenesis, or hypoxia inducible factor-1 alpha (HIF-1 alpha), a master transcription factor that regulates gene expression in hypoxia. Hence, response to cytotoxic therapy may be improved by modulating the tumor microenvironment (TME). Several agents in clinical use may do this. Some of these target vasculature, either directly or indirectly by disrupting VEGF and/or HIF-1 signaling. Many of these agents have been shown to increase radio/chemosensitivity in preclinical models. A confounding factor in terms of radiosensitization is the variable effect of these drugs on tumor oxygenation. Some of these agents ablate the vasculature, thereby increasing hypoxia. Others may normalize tumor vasculature, leading to increased blood flow and oxygenation, thereby potentially increasing radiosensitivity and the delivery of chemotherapy. Inhibitors of EGFR signaling and the PI3K/Akt pathway can also cause similar vascular changes in preclinical models, perhaps by indirectly inhibiting VEGF secretion. In summary, agents are currently available in the clinic that might modulate the TME in a way that could improve radio/chemosensitivity. The challenge is to show that this occurs in human patients and then use this information to optimize cancer therapy.

Aims: PAI-1 (plasminogen activator inhibitors-1) regulates plasminogen activation, and is related to tumour development. This study aims to test whether the promoter polymorphism in the PAI-1 gene is related to the aggressiveness of disease in prostate cancer., Materials and Methods: In the present study, Taqman SNP genotyping assay was used to detect PAI-1 4G/5G polymorphism in DNA from paraffin-embedded tissues of 98 Caucasian patients with prostate cancer., Results: The distribution of the genotypes is in Hardy-Weinberg equilibrium. The genotype had no statistically significant relationship with other prognostic factors. Similar risks for recurrence were seen in individuals with the 4G/4G and 4G/5G genotypes compared to those with 5G/5G genotype (odds ratio [OR] 2.65, 95% CI: 0.41-16.94, P = 0.30; OR = 2.19, 95% CI: 0.38-12.49, P = 0.38)., Conclusion: We concluded that PAI-1 promoter polymorphism is not associated with the aggressiveness of disease in prostate cancer.

Gene therapy involves identifying a gene of interest and then manipulating the expression of this gene through a variety of techniques. Here we specifically address gene therapy's role in cancer research. This paper will encompass thoroughly investigated techniques such as cancer vaccines and suicide gene therapy and the latest advancements in and applications of these techniques. It will also cover newer techniques such as Antisense Oligonucleotides and small interfering RNAs and how these technologies are being developed and used. The use of gene therapy continues to expand in cancer research and has an integral role in the advancement of cancer treatment.