ESMO Congress 2024 | OncologyPRO

Abstract 497P

Background

The primary site of colorectal cancer (CRC) influences survival outcomes when metastasized to the liver or lung, with left-sided CRC being associated with longer survival than right-sided CRC. Additionally, the timing of metastasis, whether synchronous or metachronous, has been suggested as a factor for survival, with synchronous metastasis generally considered more aggressive than metachronous CRC with brain metastasis (BM). We investigated the effect of both CRC’s primary location and metastatic timing on overall survival (OS) upon metastasis to the brain.

Methods

We systematically searched PubMed, Embase, and the Cochrane Library. We included studies that described patients diagnosed with BM from CRC, with reports on survival outcomes based on different primary tumor sites (left vs right) or metastatic timing (synchronous vs metachronous). Within the eligible studies, we extracted hazard ratios (HR) for OS and conducted a meta-analysis by using the random-effect model.

Results

Out of 5836 studies identified through our search, 7 studies met the inclusion criteria for the meta-analysis. Similar to lung and liver metastasis of CRC, left-sided primary CRC exhibits better OS than right-sided CRC (multivariate HR = 0.71, 95% CI: 0.54-0.94, univariate HR = 0.75, 95% CI: 0.57-0.99) when metastasized to the brain. Regarding the timing of metastasis, we found no significant difference in OS between synchronous and metachronous metastasis (HR = 0.83, 95% CI: 0.48-1.43). Table: 497P

Hazard ratio of the included studies

Study	HR	95% CI
Right colon vs left colon (reference = right), multivariate analysis
Bergen 2021	0.65	0.46-0.92
Chen 2022	0.94	0.56-1.57
Chen 2023	0.49	0.18-1.34
Total	0.71	0.54-0.94	I²: 0%
Right colon vs left colon (reference = right), univariate analysis
Bergen 2021	0.63	0.44-0.89
Bonadio 2021	1.14	0.80-1.62
Chen 2022	0.74	0.48-1.14
Chen 2023	0.37	0.17-0.81
Michl 2015	0.79	0.57-1.09
Total	0.75	0.57-0.99	I²: 58%
Synchronous vs metachronous (reference = metachronous), univariate analysis
Chen 2023	0.83	0.44-1.58
Mege 2013	0.50	0.10-2.60
Tanriverdi 2014	1.14	0.31-4.13
Total	0.83	0.48-1.43	I²: 0%

Abbreviations: HR, hazard ratio; CI, confidence interval

Conclusions

Left-sided colon cancer exhibited higher OS compared to right-sided colon cancer, consistent with findings in lung and liver metastasis. However, OS did not differ between synchronous and metachronous metastasis. Further studies comparing the genotypes and mutations of CRC with BM based on their primary location and metastatic timing are warranted.