1996 Volume 5 Issue 1 Pages 25-28
In a retrospective study of patients who underwent metastatic brain tumor surgery, we have evaluated the efficacy of intraoperative radiotherapy (IOR) for the preventlon of a local recurrence. This study consisted of 78 cases with a metastatic brain tumor that were surgically treated between 1986 to 1992. These cases were classified into three groups : patients who underwent surgery without radiotherapy (S : 36 cases), patients who underwent surgery and post-operative conventional radiotherapy (S+ R : 27 cases) , patients who underwent surgery with IOR (S+I0R : 15 cases) . Of the 78 cases, 77 involved a total resection, and the remaining case involved a subtotal resectlon. In the S+ R group, a total dose of 40-56.5 Gy (mean 45.6 Gy) was delivered by using a 10 MeV Iinear accelerator. In the S+ IOR group, a total dose of 20-25 Gy was delivered by using a betatoron. The IOR cone diameter was adjusted to include a 5 mm perimeter of normal brain tissue, and the 80% isodose line was set to penetrate 5-10 mm below the deepest aspect of the tumor. Our analysis revealed that the respective overall local relapsing-free rates for the S, S+R and S+I0R groups were : 46.2%, 88.0%, and 79.9% at 6 months : and 36.4%, 70.7%, and 79.9% at 12 months. For the lung cancer cases, the respective values were as follows : 37.5%, 82.6%, and 84.6% at 6 months ; 30.2%, 67.6%, and 84.6% at 12 months. Further, no significant differences were seen in local recurrence rates between the S+R and the S + IOR groups. The mean number of hospitalization days in all 3 groups were : 43.0 days, 75.9 days, and 37.4 days, respec-tively. Thus, the number of hospitalization days in the S+I0R group was half that of the S+R group. Based on these findings, it appears that IOR treatment resulted in as good localized tumor control as is achieved by conventional radiotherapy and that the number of days of hospitalization is shortened. These findings thus confirm that IOR therapy contributes to improving the quality of life of mestastatic brain tumor patients.
