Table 1.

Patient characteristics according to primary tumor side (PTS)

Patient characteristics	Overall ptx population		ptx with LS CRC		ptx with RS CRC		P value
	n	%	n	%	n	%
	281	100	239	85.1	42	14.9
Sex
Female	109	38.8	90	37.7	19	45.2	n.s.
Male	172	61.2	149	62.3	23	54.8
Median age at diagnosis of CRC (years)	61		61		66		0.024
Range	33-89		33-89		38-79
Stage IV at diagnosis of CRC
Yes	92	34.1	76	33.0	16	40.0	n.s.
No	178	65.9	154	67.0	24	60.0
Unknown	11 (3.9%)
RAS mutation (KRAS or NRAS)
Yes	39	79.6	33	76.7	6	100.0	n.s.
No	10	20.4	10	23.3	0	0.0
Unknown	232 (82.6%)
Visceral metastases before BM
Yes	206	78	178	78.4	28	75.7	n.s.
No	58	22	49	21.6	9	24.3
Unknown	17 (6.0%)
Liver metastases before BM
Yes	122	43.4	103	43.1	19	45.2	n.s.
No	142	50.5	125	52.3	17	40.5
Unknown	17 (6.0%)
Lung metastases before BM
Yes	177	66.5	156	68.4	21	55.3	n.s.
No	89	33.5	72	31.6	17	44.7
Unknown	15 (5.3%)
Systemic disease at diagnosis of BM
No evidence of extracranial disease and complete remission	43	16.1	36	15.7	7	18.9	n.s.
Partial remission	6	2.2	4	1.7	2	5.4
Stable disease	70	26.2	63	27.4	7	18.9
Progressive disease	126	47.2	110	47.8	16	43.2
Synchronous diagnosis of CRC and BM	22	8.2	17	7.4	5	13.5
Unknown	14 (5.0%)
Progressive systemic disease at diagnosis of BM
Yes	148	55.4	127	55.2	21	56.8	n.s.
No	119	44.6	103	44.8	16	43.2
Unknown	14 (5.0%)
Median age at diagnosis of BM (years)	65		64		69		n.s.
Range	34-89		34-89		39-81
Median KPS at diagnosis of BM	70		70		70		n.s.
Range	20-100		20-100		40-100
Median number of BM at initial BM diagnosis	1		1		1		n.s.
Range	1-3		1-8		1-5
Concomitant LC at diagnosis of BM
Yes	7	2.5	7	2.9	0	0	n.s.
No	274	97.5	232	97.1	42	100.0
First line therapy for BM
WBRT	41	14.9	36	15.5	5	11.9	n.s.
Stereotactic radiosurgery	118	42.9	98	42.1	20	47.6
Resection	109	39.6	93	39.9	16	38.1
Best supportive care	7	2.5	6	2.6	1	2.4
Unknown	6 (2.1%)
BM recurrence after initial therapy
Yes	100	40.2	91	42.3	9	26.5	n.s.
No	149	59.8	124	57.7	25	73.5
Unknown	32 (11.4%)

BM, brain metastases; CRC, colorectal cancer; KPS, Karnofsky performance status; LC, leptomeningeal carcinomatosis; LS, left-sided; n.s., non-significant; ptx, patients; RS, right-sided; WBRT, whole brain radiotherapy.

Bold value indicates difference in age at diagnosis between right and left-sided CRC.