الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Cancer is a huge public health problem worldwide, as it considered to be the second leading cause of death (Siegel et al. 2017). It was estimated that cancer caused 8.2 million cancer deaths worldwide in 2012 and this number increased to be 9.6 million cancer deaths worldwide in 2018 (Torre et al. 2015, Bray et al. 2018). Cancer rates may increase by 50% to reach 15 million new cases per year in 2020. Sincce, it develops due to several lifestyle behaviors such as smoking, overweight, physical inactivity, poor diet, and reproductive changes (Sanjoy et al. 2004, Sarkar et al. 2013). Unlike normal cells tumor originates from an excessive uncontrolled growth of structurally and biologically abnormal differentiated cells which could be found at any tissue of the body (Weinberg 1989).Tumors could be classified according to the anatomical origin of the primary tumor, microscopic appearance, and the cause of initiation (Tanaka 2009). Furthermore, tumor can also be classified into two major types’ cancerous tumor and non-cancerous tumor. The first is called malignant tumor which is a cancerous tumor which composed of cells with abnormal structures and functions, grow rapidly, spread progressively to adjacent tissues, and can metastasize (the process in which cancer cells can spread from the site of primary tumor to one or more other places in the body) (Tanaka 2009). Metastasis is the property by which tumor become more dangerous it consists of a long series of sequential, interrelated steps and depends on intrinsic properties of the cells and factors derived from the
microenvironment of the tumor (Mantovani 2008). On the other hand the second type is called benign tumor which is a non-cancerous tumor that appears in a morphological structure that resembles the morphology of the tissue of origin, grows slowly, forms encapsulated masses, do not leave the tissue it has been originated in (do not metastasize) and they are rarely fatal (Li et al. 2014).