BACKGROUNDCurrent surgical practice for nephron sparing surgery allows at least 1 cm margin of normal tissue around the tumour. However, recent studies show that the width of the margin is not important, even simple enucleation is as effective as partial nephrectomy. We explored whether margin size has significant impacts on clinical outcomes in nephron sparing surgery for renal cell carcinoma of 4 cm or less.

METHODSBetween 1998 and 2006, 115 patients with sporadic, pathologically confirmed, renal cell carcinoma 4 cm or less (T1a) and normal contralateral kidney were treated by nephron sparing surgery using a margin less than 5 mm. The surgical margin status was evaluated from frozen and permanent paraffin sections.

RESULTSMean and median tumour diameter were 3.3 cm and 3.5 cm (range 1.0-4.0). The mean margin width was 2.2 mm (median 2.0, range 0-6). In addition, 114 cases had margins 5 mm or less (99.1%), 97 cases (84.3%) had margin 3 mm or less, and 26 cases had margin zero (22.6%). None of the patients had positive surgical margins. No patients died during follow-up (mean 65 months). There were no any major surgical complications and no distant metastasis was detected. Local recurrence was detected in one case (0.9%) at a different site of the kidney.

CONCLUSIONSFor early localized renal cell carcinoma of 4 cm or less, as long as tumour is completely excised, the size of margin in nephron sparing surgery is not important. Nephron sparing surgery with 5 mm margin is enough for tumour control. It provides excellent renal function preservation, favourable long term progression free survival and is not associated with an increased risk of local recurrence.