Stage I 
TNM T1, N0, M0 
T2, N0, M0
In Robson's staging system, Stage I means the tumor is confined within the renal capsule and is either less than 3/4 in. (2 cm) (T1) or more than 3/4 in. (2 cm) (T2) and with no lymph node or distant metastases.
    About one-third of cases present with Stage I disease, many of which are Grade I (very well-differentiated) to Grade II (moderately well-differentiated). Almost one-third of Stage I cases are found to have micrometastases or microscopic disease after surgery.

Standard Treatment  Simple or radical nephrectomy. It can be partial in selected cases, for low-grade small masses less than 1 1/4 in. (3 cm) in the cortex or outer area of the kidney, for tumors within one kidney and for tumors in both kidneys.
    As long as tumor-free surgical margins are obtained, partial nephrectomy can be performed either with the kidney in place but isolated from the normal blood supply or by using an ex vivo technique, in which the kidney is removed from the body (so-called bench surgery). Bench surgery is needed for tumors in the middle portion of the normal kidney. After excision of the tumor, the remaining normal kidney is autotransplanted back into an appropriate area.