Chemotherapy circulates throughout your body within the bloodstream. therefore it can treat cancer cells almost any place in the body. This is known as systemic treatment. Antimetabolites are cell cycle specific. Antimetabolites are most effective during the S-phase of cell division as a result of they primarily bear on cells undergoing synthesis of recent DNA for formation of recent cells. The toxicities related to these medicine are seen in cells that are growing and dividing quickly.