Stereotactic Radiotherapy Group Research Articles

Treatment of Portal Vein Tumor Thrombosis of Hepatoma Patients with Either Stereotactic Radiotherapy or Three-Dimensional Conformal Radiotherapy

Patients with hepatocellular carcinoma (HCC) often have unresectable tumors. Transcatheter arterial chemoembolization (TACE) is one of the limited alternative treatments that can prolong these patients' survival. However, the presence of portal vein tumor thrombosis (PVTT) is a contraindication for TACE and, therefore, HCC patients with PVTT would be depleted of the advantage of TACE. The purpose of this study was to analyze the recanalization rate of thrombosed portal vein and treatment toxicities after stereotactic radiotherapy (SRT) or three-dimensional conformal radiotherapy (3DCRT). From March 2002 to November 2004, 43 patients were enrolled in this prospective study. Twenty-two patients were in the SRT group and 21 in the 3DCRT group. For SRT, 3 Gy per fraction, 3 fractions per week, was given to a total dose of 45 Gy. For 3DCRT, a daily dose of 1.8 Gy, 5 fractions per week, was given to a total dose of 45 Gy. Of the 43 patients, 16 completed the planned radiotherapy. Eventually, 14 patients received evaluation for portal vein recanalization, 8 in the SRT and 6 in the 3DCRT group, respectively. For all patients, the crude response rate was 26%. For 14 evaluable patients, the crude response rate was 79%. It was 75% in the SRT group and 83% in the 3DCRT group (P = 0.71). The median survival time was 6.0 and 6.7 months for the SRT and 3DCRT group, respectively (P = 0.911). Image-based radiotherapy, either SRT or 3DCRT, can recanalize the PVTT in unresectable HCC patients. Responders also had better 1 year and 2 year survivals. A more strict patient selection criterion may maximize the potential benefits of radiotherapy for hepatoma patients with PVTT.

Stereotactic radiosurgery and fractionated stereotactic radiotherapy for the treatment of acoustic schwannomas: comparative observations of 125 patients treated at one institution

Background: Stereotactic radiosurgery (SRS) and, more recently, fractionated stereotactic radiotherapy (SRT) have been recognized as noninvasive alternatives to surgery for the treatment of acoustic schwannomas. We review our experience of acoustic tumor treatments at one institution using a gamma knife for SRS and the first commercial world installation of a dedicated linac for SRT. Methods: Patients were treated with SRS on the gamma knife or SRT on the linac from October 1994 through August 2000. Gamma knife technique involved a fixed-frame multiple shot/high conformality single treatment, whereas linac technique involved daily conventional fraction treatments involving a relocatable frame, fewer isocenters, and high conformality established by noncoplanar arc beam shaping and differential beam weighting. Results: Sixty-nine patients were treated on the gamma knife, and 56 patients were treated on the linac, with 1 NF-2 patient common to both units. Three patients were lost to follow-up, and in the remaining 122 patients, mean follow-up was 119 ± 67 weeks for SRS patients and 115 ± 96 weeks for SRT patients. Tumor control rates were high (≥97%) for sporadic tumors in both groups but lower for NF-2 tumors in the SRT group. Cranial nerve morbidities were comparably low in both groups, with the exception of functional hearing preservation, which was 2.5-fold higher in patients who received conventional fraction SRT. Conclusion: SRS and SRT represent comparable noninvasive treatments for acoustic schwannomas in both sporadic and NF-2 patient groups. At 1-year follow-up, a significantly higher rate of serviceable hearing preservation was achieved in SRT sporadic tumor patients and may therefore be preferable to alternatives including surgery, SRS, or possibly observation in patients with serviceable hearing.

Comparison between observation policy and fractionated stereotactic radiotherapy (SRT) as an initial management for vestibular schwannoma

Purpose: To compare the use of an observation policy with that of stereotactic radiotherapy (SRT) for treatment of vestibular schwannoma.Methods and Materials: The study group consisted of 27 patients who underwent observation as an initial treatment (observation group) and 50 who received SRT (SRT group). The mean follow-up period was 35 months and 31 months, respectively. Stereotactic radiotherapy consisted of small-field fractionated radiotherapy (36–44 Gy in 20–22 fractions over 6 weeks) with or without a subsequent 4-Gy single irradiation boost.Results: Actuarial tumor control rate of the SRT group was significantly better than that of the observation group (p < 0.0001). The mean growth was 3.87 mm/year in the observation group and −0.75 mm/year in the SRT group (p < 0.0001). Eleven patients (41%) in the observation group and 1 (2%) in the SRT group received salvage therapy (p < 0.001). There was no difference in the actuarial Gardner and Robertson’s class preservation curves for 5 years after the initial presentation.Conclusion: Stereotactic radiotherapy using a fractionated schedule provides a better tumor control rate and a similar rate of deterioration for hearing levels compared to an observation policy. Initial SRT may be a reasonable alternative to a wait-and-see policy.