Liver, renal, and retroperitoneal tumors: stereotactic radiotherapy.

Stereotactic body radiation therapy (SBRT) is currently under active study at numerous centers for clinical application in the management of patients with primary or metastatic tumors of the liver, primary or metastatic tumors of the kidney, and selected other retroperitoneal tumors. Accurate patient positioning and tumor relocalization are essential for SBRT use in the liver and other abdominal and retroperitoneal sites, as at other tumor sites. In a phase I clinical trial at the University of Colorado, patients with liver metastases have received SBRT. Eligible patients had 1-3 discrete liver metastases and no prior radiotherapy to the liver. The aggregate tumor diameter (sum of diameters) was <6 cm. Respiratory control was used. Normal liver volume to be preserved was determined prior to therapy. Dose was prescribed to a planning target volume that included the gross tumor volume plus at least a 5-mm radial and 10-mm superior-inferior margin. SBRT was administered with 6- to 15-MV beams through either dynamic conformal arcs or a combination of multiple noncoplanar static beams. The dose was safely escalated to 60 Gy in 3 fractions. After SBRT to hepatic lesions, it is extremely difficult to radiographically evaluate tumor response within the first few months, and radiographic response analysis may require 4-6 months after SBRT. Care must be taken to avoid focal high-dose therapy to the gastrointestinal mucosa, where the maximum point dose is likely to be the major limitation rather than the mean dose. SBRT has a potential role in the management of renal cell carcinoma, either as an alternative to surgery to the primary site or as cytoreductive therapy directed toward metastatic sites, and in the management of selected retroperitoneal tumors.

Extracranial stereotactic radiotherapy for primary and metastatic renal cell carcinoma.

BACKGROUND AND PURPOSE: We investigated the results of using stereotactic radiotherapy (SRT) for 58 patients with renal cell carcinomas (RCC) who were evaluated restrospectively for response rates, local control rates and side effects. PATIENTS AND METHODS: From October 1997 to January 2003, 50 patients suffering from metastatic RCC and eight patients with inoperable primary RCC received high-dose fraction SRT while placed in a stereotactic body-frame. The most common dose/fractionation schedules used were 8 Gyx4, 10 Gyx4 and 15 Gyx3 during approximately 1 week. RESULTS: SRT-treated tumor lesions regressed totally in 30% of the patients at 3-36 months, whereas 60% of the patients had a partial volume reduction or no change after a median follow-up of 37 months (SD 17.4) for censored and 13 months (SD 12.9) for uncensored patients. Side effects were generally mild. Of 162 treated tumors, only three recurred, yielding a local control rate of 90-98%, considering the 8% non-evaluable sites as defined here. For patients with one to three metastases, the time to new spread was 9 months. CONCLUSIONS: Our use of SRT for patients with primary and metastatic RCC yielded a high local control rate with low toxicity. Patients with one to three metastases, local recurrences after nephrectomy or inoperable primary tumors benefited the most, i.e. had fewer distant recurrences (13/23) and longer survival times compared to patients with >3 metastases (24/27 recurrences).