Cancer is a non-infectious disease and yet it is a major cause of death all over the globe. Cancer cells are dead-opposite of normal cells, i.e., they lack cristae in mitochondria, has abnormal cell cycle, are immortal, etc.
The cancer cells present in a patient will continuously divide without maturation of cells, forming a large mass of cells called ‘tumours’. As there is the presence of oxygen and food-particles within the host cell, the cancer cells sucks out the food-particles and will be affecting the normal cells.
As this continues, the tumours will spread all over the body, besides it makes the patient to suffer.
As the tumour spreads, the quantity of normal cells will be less as compared to infected cells. Hence, as a person can not withstand the pain (underarm pain, weakening of body, etc), the person will die.
Thanks. Hope you are clear.