Background: Whole brain radiotherapy (WBRT) is the most common treatment for brain metastases. Survival of patients with cancer of unknown primary (CUP) presenting with brain metastases is extremely poor. A radiation program with a short overall treatment time (short-course RT) would be preferable to longer programs if it provides similar outcomes. This study compares short-course RT with 20 Gy in 5 fractions (5 x 4 Gy) given over 5 days to longer programs in CUP patients.
Patients and methods: Data regarding 101 CUP patients who received either short course WBRT (n=34) with 5 x 4 Gy or long-course WBRT (n=67) with 10 x 3 Gy given over 2 weeks or 20 x 2 Gy given over 4 weeks for brain metastases were analyzed retrospectively. Six additional potential prognostic factors were investigated: age, gender, Karnofsky performance score (KPS), number of brain metastases, extracranial metastases, RPA-(Recursive Partitioning Analysis-)class.
Results: On univariate analysis, the radiation program was not associated with survival (p=0.88) nor intracerebral control (p=0.36). Improved survival was associated with KPS >or= 70 (p<0.001), absence of extracranial metastases (p<0.001), and RPA-class 1 (p<0.001). On multivariate analyses, KPS (risk ratio [RR]: 4.55; p<0.001), extracranial metastases (RR: 1.70; p=0.018), and RPA-class (RR: 2.86; p<0.001) maintained significance. On univariate analysis, KPS (p<0.001) and RPA-class (p<0.001) were significantly associated with intracerebral control. On multivariate analyses, KPS (RR: 2.72; p<0.001) and RPA-class (RR: 2.09; p<0.001) remained significant.
Conclusion: Short-course WBRT with 5 x 4 Gy provided similar intracerebral control and survival as longer programs for the treatment of brain metastases in CUP patients. 5 x 4 Gy appears preferable because it is more convenient for patients.