Stage
This cross section of the female pelvis shows the bones and muscles at the sides of the diagram.  The uterus, cervix, and vagina are represented by the dashed lines in the center of the drawing.  The solid black area represents a cervical cancer limited to the cervix and, therefore, categorized as a Stage 1 process.
This diagram shows a Stage 2B cervical cancer.   The cancer has spread into the tissue located immediately outside of the cervix (parametria).
This cervical cancer has spread to the muscles forming the boundary of the pelvis.  By definition this is categorized as a Stage 3B process.
This cross section of the female pelvis shows the sacrum on the right and the pubic bone on the left.  The dashed lines represent the bladder, uterus, vagina and rectum.  This cervical cancer is eroding into the rectum and is classified as Stage 4A.