ABSTRACT
According to the World Health Organization (WHO), cancer is the number one cause of mortality worldwide, accounting for 7.6 million deaths, or 13% of all deaths, across the globe in 2008 [1]. The toll is expected to rise continuously to over 11 million in 2030. Environmental factors are believed to be a primary contributor to the pathogenesis. The hazards range from physical agents such as ionizing and ultraviolet radiations, chemical agents such as dioxins and arsenic, to biological agents such as human papillomavirus and hepatitis B virus. Other risk factors include smoking, alcoholism/diet, obesity, ageing and genetics. Cancer cells, with mutated genomes, share three characteristics: uncontrolled cell multiplication, invasion of adjacent tissues, and migration to non-adjacent sites [2]. Metastasis of cancer, usually via bloodstream or lymphatics, to other vital organs
such as lungs, liver, brain and bones adds to the malignancy and worsens the prognosis of the disease.
