Further developments for improving response and tolerance to irradiation for advanced renal cancer: concurrent (mTOR) inhibitor RAD001 and helical tomotherapy.

Purpose: Radiotherapy remains marginal in the treatment of renal cell carcinoma (RCC), due to radioresistance and risks of acute toxicity. However, recent data have shown that the m-TOR inhibitors could decrease the tumor resistance to ionizing radiation. At the same time, new highly conformal irradiation modalities may significantly improve the tolerance to radiation.

Methods: Here, we report the first case of concurrent use of mTOR antagonist, rapamycin and Helical Tomotherapy and its potential in critical organs sparing in a patient with retroperitoneal relapse from a RCC. He was treated with Everolimus, 10 mg/d and concurrent Helical Tomotherapy to the region of the recurrence (45 Gy, 1.8 Gy per fraction).

Results: Helical Tomotherapy allowed very sharp dose distributions around the target volumes, while sparing critical organs from useless radiation. No radiotherapy related acute toxicity was observed. At last follow-up (6 months later), the patient remains in partial remission at the irradiated region.

Conclusions: While targeted agents might find applications for radiosensitizing purposes, this report highlights the potential of Helical Tomotherapy for reducing the doses delivered to the critical organs, thus improving tolerance to irradiation.