Clinical features and prognostic factors of brain metastases from colorectal cancer: a single center experience
Authors: Gao Zhao , Jin Xuan , Wu Shikai 
Published: April 2023

Abstract
Purpose: The study aimed to investigate the clinical characteristics, prognostic factors, survival times, and therapy outcomes of brain metastases (BM) from colorectal cancer (CRC).
Methods: The clinical characteristics of 25 patients with BM from CRC were retrospectively analyzed. The time of the occurrence of BM after diagnosis of CRC was recorded. Meanwhile, the time from the occurrence of lung, bone, liver, and other extracranial metastases to the occurrence of BM was also recorded. We evaluate the time factors affecting the length of the occurrence of BM and the potential prognostic factors after BM diagnosis. The influences of patients undergoing surgery-based comprehensive treatment, radiotherapy-based comprehensive treatment, and co-medication were also assessed.
Results: In patients with BM from CRC, lung metastases (13/25) occurred at a higher frequency than liver metastases (8/25) and bone metastases (6/25). The median time to the development of BM was much shorter (3.7 vs. 25.3 months, p=0.027), with the brain being the origin site for the metastasis. The median overall survival reached 9.9 months. The interval between diagnosis of BM and bone, liver, and lung metastasis remains 3, 6.5, and 11 months, respectively. The brain lesions of patients with BM alone had higher rates in supratentorial (88.9%), while those with extracranial metastasis had a 62.5% incidence of infratentorial metastasis. The difference was statistically significant (p<0.05). The time of occurrence of BM in patients aged 67 years and younger was 16.1 and 30.1 months, respectively. The differences between them were statistically significant (p=0.043). The BM time for left- and right-sided colon cancer were 26.5 and 7.8 months, representing a statistically significant difference (p=0.015). The time to onset of BM for patients with and without the resection of primary lesions was 25.4 and 4.5 months. Statistically significant differences are shown (p=0.007). Univariate analysis demonstrated that the prognosis of patients was related to the KPS score, the number of BM, treatment methods, and the occurrence of lung metastasis (p<0.05). The multivariate analysis revealed that the treatment modality and lung metastasis were independent prognostic factors for CRC patients with BM. Right-sided CRC patients with BM have poor prognosis (8.1vs10.2months, p=0.31). Although median survival time was not significantly different between patients with and without bevacizumab combination therapy, bevacizumab therapy is associated with a better survival time (9.9 vs. 7.1 months, p = 0.27).
Conclusion: Patients with left-sided CRC, especially those with lung metastases, are prone to brain metastases, and patients with brain metastases as the first metastatic site have a higher rate of supratentorial metastases. Young patients with right hemicolon cancer, and patients who have not undergone primary lesion resection have a shorter time for the occurrence of BM. Patients with colorectal lung metastases, especially those young with right-sided CRC, require close imaging surveillance of BM. The prognosis of CRC patients with BM and lung metastases is poor, and comprehensive treatment based on surgery could significantly prolong patients' survival time.