This is because the chemotherapy may be absorbed slowly through the muscular tissues and into the bloodstream. Certain forms of cancer have a tendency to spread to the nervous system. To treat cancer that spreads to the spinal cord or brain, doctors may perform a spinal tap and inject chemotherapy into the spinal fluid. This is known as the intrathecal method of administration. For some patients, IV insertions can eventually damage the veins in the arm.
Some patients have small veins and some have very few accessible veins.
Frequent IV insertions and too small or too few veins may prompt the doctor to recommend a permanent type of IV catheter. Permanent catheters allow patients to go home and receive chemotherapy without needing other IV's placed. Along with receiving chemotherapy and IV fluids through this catheter, patients can receive blood products and even have their blood drawn without painful needle sticks. All work in similar ways. Care of these catheters may be a little different, but the principle of insertion is similar.