Table 1. Baseline characteristics.

	De novo		Recurrent all			Recurrent with MFI ⩽24 months			Recurrent with MFI >24 months
	n=154		n=661			n=176			n=485
Characteristics	No.	%	No.	%	P-value	No.	%	P-value	No.	%	P-value
Age at diagnosis of metastatic disease
Median, (range)	61	25–89	64	25–93	0.06	62	25–93	0.40	64	32–90	0.04
<40 years	10	6	18	3		12	7		6	1
40–70 years	100	65	408	62		98	56		310	64
>70 years	44	29	235	35		66	37		169	35
Primary tumour stagea
T1	9	25	240	44		38	31		202	48
T2	22	63	265	48		73	58		192	45
T3	2	6	29	5		8	6		21	5
T4	2	6	16	3		6	5		10	2
Unknown	119		111			51			60
Regional lymph node stage primary tumoura
N0	6	17	230	41		46	37		184	43
N1	13	37	187	34		32	25		155	36
N2	6	17	82	15		26	21		56	13
N3	10	29	57	10		22	17		35	8
Unknown	119		105			50			55
Histological grade of primary tumour
SBR 1	8	11	55	11	0.26	10	6	0.01	45	14	0.59
SBR 2	39	53	212	44		57	37		155	47
SBR 3	26	36	219	45		89	57		130	39
Unknown	81		175			20			155
Hormone receptor status
Positive	121	81	490	76	0.21	96	55	<0.0001	394	83	0.43
Negative	29	19	156	24		78	45		78	17
Unknown	4		15			2			13
HER2 status
Positive	34	23	122	19	0.29	37	21	0.76	85	18	0.21
Negative	116	77	524	81		137	79		387	82
Unknown	4		15			2			13
Prior (neo)adjuvant chemotherapy
Yes	—		306	46		85	48		221	46
No			355	54		91	52		264	54
Prior (neo) adjuvant endocrine therapy
Yes	—		339	51		64	36		275	57
No			322	49		112	64		210	43
Prior (neo) adjuvant anti-HER2 therapy
Yes	—		44	7		17	10		27	6
No			617	93		159	90		458	94
No. of metastatic sites
1	103	67	426	64	0.57	123	70	0.56	303	62	0.32
⩾2	51	33	235	36		53	30		182	38
Site of metastases
Bone	60	39	202	31	0.04	41	23	0.002	161	33	0.19
Visceral	37	24	188	28	0.27	58	33	0.07	130	27	0.49
Brain	0	0	26	4	0.01	18	10	<0.0001	8	2	0.11
Skin and lymph nodes	9	6	46	7	0.62	16	9	0.27	30	6	0.88
Multiple	48	31	199	30	0.80	43	25	0.17	156	32	0.82
Any palliative chemotherapy
Yes	88	57	350	53	0.35	84	48	0.09	266	55	0.62
No	66	43	311	47		92	52		219	45
Any palliative endocrine therapy
Yes	106	69	408	62	0.10	67	38	<0.0001	341	70	0.73
No	48	31	253	38		109	62		144	30
Any palliative targeted therapy
Yes	33	21	121	18	0.37	23	13	0.04	98	20	0.74
No	121	79	540	82		153	87		387	80

Abbreviation: SBR=Scarff Bloom Richardson.

^aPathological TNM according to the sixth edition of the TNM classification of malignant tumours.