Table 2.

Metastatic breast cancer characteristics according to age groups.

	All		Age at MBC						P value between age groups
			<40 years		[40–60] years		>60 years
	N	%	N	%	N	%	N	%
Time to first metastasis									<0.0001
De novo (< 3 months)	4058	28.2%	339	31.5%	1849	28.7%	1870	27.1%
[3–24[ months	2284	15.9%	308	28.6%	1114	17.3%	862	12.5%
>= 24 months	8035	55.8%	429	39.8%	3461	53.8%	4145	60.2%
NA	26	0.2%	1	0.1%	12	0.2%	13	0.2%
Number of metastatic sites									0.02
One site	7976	55.4%	572	53.1%	3493	54.3%	3911	56.8%
Two sites	3473	24.1%	267	24.8%	1586	24.6%	1620	23.5%
Three or more sites	2954	20.5%	238	22.1%	1357	21.1%	1359	19.7%
Type of metastasis									<0.0001
Bone only	8145	65.3%	562	52.2%	3587	55.7%	3996	58.0%
Visceral	4584	15.6%	391	36.3%	2140	33.3%	2053	29.8%
Other (neither visceral nor bone)	1674	19.1%	124	11.5%	709	11.0%	841	12.2%
Tumor subtype									<0.0001
HoR + HER2-	9398	15.6%	519	48.2%	3934	61.1%	4945	71.8%
HoR-HER2-	2247	19.1%	272	25.3%	1138	17.7%	837	12.1%
HER2+	2758	65.3%	286	26.6%	1364	21.2%	1108	16.1%
De novo MBC –treatment of primary tumor <1y from diagnosis
Breast surgery	691	17.0%	90	26.5%	374	20.5%	227	12.1%	0.001
Loco-regional RT	1333	32.8%	173	51.0%	705	38.1%	455	24.3%	<0.0001