[Radiotherapy of malignant lymphomas of the brain: Radiologic behavior in relation to radiation dose and volume].

PURPOSE

During the radiotherapy of malignant CNS-lymphomas computertomographic controls were performed as a routine. The radiologic results should give a base to define the total dose. The aim was to determine the value of such individual parameters.

PATIENTS AND METHODS

Fourteen years ago the prospectively defined treatment concept included a parallel opposed whole brain irradiation slowly increasing with 1 x 1.0 Gy, 1 x 1.5 Gy, 1 x 2.0 Gy, then 10 x 3 Gy, followed by a radiological control and whenever possible a boost to the initially involved region with 7 to 10 x 2 Gy.

RESULTS

From 1. 1. 1979 to 31. 12. 1993 28 patients with a malignant non-Hodgkin-lymphoma of the brain have been seen at the state hospital in Aarau. Fifteen cases suffered from a primary involvement of the brain, 13 showed a secondary manifestation. 20/28 (71%) presented radiologically, cytologically or at autopsy as multifocal disease. Histologic examination mainly detected intermediate or high-grade lymphomas. 25 patients have been irradiated. In 4 out of them the radiation concept couldn't be realized. CT-results were as follows: after 30 to 40 Gy: CR = 2/21 (9.5%); after 45 to 55 Gy: CR = 10/19 (53%); after 1 to 3 months: CR = 12/15 (80%). Nine local relapses occurred, 3 out of them regrowed multifocally and therefore were detected also within the boost region. Six recurrences were outside in the lower dosed areas. No severe side effects have been observed.

CONCLUSIONS

Most of the tumors disappeared radiologically not before 1 to 3 months after radiation. Recurrences are mainly seen in the lower dosed region. The incidence and the localisation of the recurrences give some reason to the idea, that the computertomography of these tumors does not detect properly there prior extensions.