TUMOR-RELATED PROGNOSTIC FACTORS FOR REMISSION OF BRAIN METASTASES AFTER RADIOTHERAPY

Purpose: To study CT determined response to external beam radiotherapy as well as influence of tumor-related factors, especially of tumor vo lume, on remission and to evaluate whether particular subgroups of met astases are controlled by low-dose radiotherapy, Methods and Materials : Contrast enhanced CT scans before and after radiotherapy were analyz ed, Inclusion criteria: brain metastases treated with whole-brain radi otherapy (10 fractions of 3 Gy over 2 weeks) since 1983; no additional treatment, for example, surgery or chemotherapy; at least one follow- up CT, Three hundred thirty-six metastases from 108 patients were eval uated with regard to their volume, extent of necrosis, histology of pr imary tumor, and interval between radiotherapy and follow-up CT. All p arameters were correlated with best local result and progression-free survival by uni-and multivariate tests, Volume-response curves were ca lculated, Results: In univariate analysis local result was significant ly influenced by each of the four parameters mentioned above, Complete remission was observed in 37% of metastases from small-cell carcinoma , 35% of those from breast cancer, 25% of those from squamous-cell car cinoma, and 14% of those from nonbreast adenocarcinoma, The rate was 5 2% for metastases <0.5 cm(3) and 0% for those >10 cm(3). In multivaria te analysis, small volume and no necrosis were the most important prog nostic factors for complete remission, Progression-free survival was i nfluenced by best local result, Conclusion: With radiotherapy to a tot al dose of 30 Gy even small metastases had a complete remission rate o f 52% only, Therefore, patients should be treated,vith locally more ef fective dose and fractionation schedules when local control is the aim , However, partial remission rate was remarkable even for large and ne crotic metastases, This should be considered when palliation is the ai m of treatment, (C) 1997 Elsevier Science Inc.