Tobacco smoke also contributes to vasoconstriction and thus increased blood pressure, heart rate and cardiac workload, which reduces oxygen delivery to the tissues (Ambrose, 2004; National Centre for Smoking Cessation and Training [NCSCT], 2011).Tire subsequent rise in red blood cell production leads to increased blood viscosity, reduced oxygen supply to the body's tissues and potential thrombosis. Reduced oxygenation also decreases the efficacy of radiotherapy treatment and can possibly lead to chemo-insensitivity (Yamashita et al, 2014).