Brain Metastasis in Colorectal Cancer Patients: Survival and Analysis of Prognostic Factors.

Background: The purpose of the study was to characterize the rare cohort of patients (pts) with metastatic colorectal cancer (mCRC) and brain metastasis (BM) and to identify prognostic subgroups.

Patients And Methods: In collaboration with the Munich Cancer Registry, pts with mCRC and BM who were diagnosed between 1998 and 2011 were identified. Survival from the time of first diagnosis of colorectal cancer (CRC) (OS-1), from the time of diagnosis of metastatic disease (OS-2) and of BM (OS-3) was calculated regarding (1) the temporal occurrence of extra- and intracranial metastasis (meta- vs. synchronous) and (2) tumor and patient characteristics. For survival analysis the Kaplan-Meier estimator and Cox regression models were used.

Results: A total of 228 pts (134 male [59%], 94 female [41%]) were identified. The median age was 63 years (142 pts [62%] were 65 years of age or younger). Most pts presented with primary tumors staged T3/4, N+, Grade 2. The primary tumor was located predominantly in the left colon (155 pts; 68%), especially in the rectum (95 pts; 42%). Median OS-1 was 35.6 months (95% confidence interval [CI], 30.1-41.1 months), OS-2 was 16.5 months (95% CI, 13.9-19.1 months), and OS-3 was 2.0 months (95% CI, 1.5-2.5 months). Median time from first CRC diagnosis to BM was 29.2 months. Subsequent BM after extracranial metastasis were observed in 184 pts (80.7%), whereas 31 pts (13.6%) presented with solitary BM. Univariate analysis did not reveal a prognostic variable for overall survival after diagnosis of BM.

Conclusion: This study presents the largest number of pts with mCRC and BM analyzed to date. The results show that most mCRC pts develop BM as a late step in the course of disease. Median time from first CRC diagnosis to BM is 29.2 months. Only a few pts were diagnosed with BM early in the disease or with solitary BM. When BM is present survival is poor.