Another example of the precision of lasers is in the removal of otherwise inoperable tumors of the brain and spinal cord, where surrounding tissue must be left undisturbed. With conventional surgery it is usually impossible to remove all the malignant cells, which often spread to other parts of the body. Although such operations are still in the experimental stage, it is hoped that before long even the most inaccessible tumor will be within reach of a laser’s cutting beam.