Stereotactic Radiotherapy for Renal Cancers

Stereotactic radiotherapy is a technique that allows the delivery of a high dose of radiation over few fractions (3-6) with great precision. It thus allows "tumor ablation" and optimal preservation of healthy tissues. Initially developed in small-sized (\<5 cm) lung cancers this technique it gives results very close and or even equivalent to those of surgery. Stereotactic radiotherapy of brain metastases of renal cancers has shown that high doses of radiation allows local control in 90 to 98% of cases. A study conducted in Sweden (Wersall et al.) underline the interest to develop stereotactic radiotherapy in primary renal tumors. In Cleveland (USA) two phase I studies are already underway. The investigators propose to develop a phase I study for tumors of less than 4 cm. As found in lung cancers, stereotactic radiotherapy can provide a non-invasive, painless and rapid (4 to 5 fractions) method for the treatment of renal cancers with a high rate of local control. The primary objective is to define the maximal tolerated dose for one fraction in stereotactic mode of renal tumors ≤ 4 cm in length using an a four-step dose increase: * Step 1: 4 x 8 Gy. * Step 2: 5 x 8 Gy. * Step 3: 4 x 10 Gy. * Step 4: 4 x 12 Gy. The patients will be followed during treatment with evaluation of acute toxicities before each session, then at 15 days, 6 weeks, 3 months, 9 months, 12 months, and then every 6 months for a total duration of 5 years after treatment.