Colorectal cancer metastasis to the brain: A scoping review of incidence, treatment, and outcomes

Table 1 Summary of literature on factors influencing incidence and prognosis of colorectal cancer brain metastases

Factor	Incidence	Prognosis	Ref.
Advanced age	Inconclusive	Inconclusive	[3,20-30]
Sex	Inconclusive	Inconclusive	[13,22,24,28,30-33]
African American race	Inconclusive	Worse	[15,25]
Poor access to health insurance	Inconclusive	Worse	[33]
Residence in urban areas	Inconclusive	Worse	[35]
Synchronicity with primary tumor	Lower	Inconclusive	[39-41]
Rectal primary tumor	Higher	Worse	[4,17,20,25,26,27,33,39,43]
Right-sided primary tumor	Higher	Worse	[4,17,25,33,43]
Tumor stage	Inconclusive	Worse	[5,25,35,44,45]
Adenocarcinoma histology	Higher	Worse	[20,22,24,25,26,46-49]
CEA levels	Higher	Inconclusive	[26,46,50]
HCMV infection	Inconclusive	Worse	[2,34,51]
Size of primary tumor	Higher	Inconclusive	[2]
Size of BM	-	Worse	[3,28,47,52,54]
Number of BMs	-	Inconclusive	[16,23,41,54]
Location of BM	-	Inconclusive	[25,30,34,56-59]
Multiple extracranial metastatic lesions	-	Worse	[60]
Concomitant lung metastasis	Higher	Worse	[18,24,22,38,44,52]
Concomitant liver metastasis	Higher	Inconclusive	[3,18,23,24,30,38,41,62,63]
Concomitant bone metastasis	Higher	Inconclusive	[5]
KPS > 70	-	Worse	[41,42,51,52,65,66,68,69]
Higher RPA score	-	Worse	[42,64]

BM: Brain metastases; CEA: Carcinoembryonic antigen; HCMV: High-grade human cytomegalovirus; KPS: Karnofsky performance status; RPA: Recursive partitioning analysis.