The perirenal fat may alter renal function by secreting fibrotic inflammatory agents when accumulates during obesity. Nephrectomy for renal tumor is a model that would provide tissue samples to test this hypothesis. Renal tumor could itself be responsible for inflammation and fibrosis in its environment. This study aims to measure the influence of the tumor on his kidney Environment and fat and define molecular markers not influenced by renal tumor. The main objective is to compare the inflammation of the perirenal fat taken in two locations in the same patient, in contact and 4 cm from the outer edge of the tumor, each patient as his own control. The secondary objective is to compare the degree of interstitial fibrosis of the renal cortex in the same sampling methods.

Inclusion Criteria:

• Age 18 years or more
• Indication nephrectomy for kidney tumor
• Stadium T1a, T1b or T2 and M0 according to the TNM (Tumor Nodes Metastasis) classification of tumors

Exclusion Criteria:

• Nephrectomy indication for chronic pyelonephritis
• Asian topic because of the difference threshold values used to characterize the metabolic syndrome in this population
• Diabetes type I or II due to a high score of renal interstitial fibrosis
• Infection with HIV (Human immunodeficiency virus)
• Partial nephrectomy (a part of the kidney on the side of the tumor is left in place)

Recruitment is in hospital, all patients being hospitalized in case of nephrectomy for kidney cancer. The treatment will be done like habitually and fat will be sample.