The tumor is found only in the vulva or perineum (area between the rectum and the vagina). Stage I is divided into stages IA and IB. In stage IA, the tumor is 2 centimeters or smaller and has spread 1 millimeter or less into the tissue of the vulva. Cancer has not spread to the lymph nodes. In stage IB, the tumor is larger than 2 centimeters or has spread more than 1 millimeter into the tissue of the vulva. Cancer has not spread to the lymph nodes.