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.

Table 2 Summary of the literature on molecular mutations influencing incidence and prognosis of colorectal cancer brain metastases

Mutation	Incidence	Prognosis	Ref.
CMS3	Higher	Inconclusive	[75]
KRAS	Higher	Inconclusive	[75,80-91]
HER2	Higher	Inconclusive	[91-94,96,98]
HER2 & NT-3	Inconclusive	Worse	[98]
20q11.1 gain	Higher	Inconclusive	[100]
MGMT methylation	Higher	Inconclusive	[102]
V600E BRAF	Higher	Inconclusive	[103,104]

BRAF: B-rapidly accelerated fibrosarcoma; HER2: Human epidermal growth factor 2; KRAS: Kirsten rat sarcoma viral oncogene homolog; MGMT: O6-methylguanine-DNA methyltransferase; NT-3: Neurotrophin-3.

Table 3 Analysis of surgical resection compared with other treatment modalities in patients with brain metastases from colorectal carcinoma

Ref.	Group 1	Group 2	Outcome	HR/OR	95%CI	Statistical significance	Analysis method
Chang et al[126], 2022	Surgery	Radiotherapy	Survival outcomes	HR = 0.53	0.47-0.6	I2 = 0%	Univariate analysis
Gui et al[130], 2025	Surgical resection	No resection	Overall survival	HR = 0.58	0.39-0.86	P = 0.006	Univariate analysis
Gui et al[130], 2025	Surgical resection	No resection	Overall survival	HR = 0.81	0.52-1.25	P = 0.3	Multivariate analysis
Suzuki et al[131], 2014	Surgical resection	No resection	Overall survival	HR = 0.26	0.17-0.41	P < 0.0001	Multivariate analysis
Kye et al[132], 2012	Conservative management	Treatment modality	Overall survival	HR = 7.973	1.487-42.761	P = 0.015	Multivariate analysis
Bonadio et al[13], 2021	Surgery alone	No local therapy	Overall survival	HR = 0.56	0.34-0.90	P = 0.018	Multivariate analysis
Bonadio et al[13], 2021	Surgery + radiotherapy	No local therapy		HR = 0.27	0.16-0.43	P < 0.001	Multivariate analysis
Wong et al[137], 2024	Surgery	WBRT	Overall survival	OR = 0.540	0.233-1.250	P = 0.150	Multivariate analysis
Wong et al[137], 2024	Surgery + WBRT	WBRT		OR = 0.232	0.107-0.504	P < 0.001	Multivariate analysis

CI: Confidence interval; HR: Hazard ratio; OR: Odds ratio; WBRT: Whole-brain radiotherapy.