Table 1. Clinical characteristics of patients with bilateral breast cancer and metastatic breast cancer.

Patient ID	Tumor 1				Tumor 2				Diagnosis
	Age (years)	Anatomical site	Subtype	TNM stage	Time since cancer 1	Anatomical site	Subtype/histologic type	TNM stage
1	55	Breast	Luminal	T2N0M0	1 month	Contralateral breast	Luminal	T3N0M0	Synchronous BBC
2	55	Breast	HER2-enriched	T2N1Mx	1 month	Contralateral breast	Luminal	T1N0Mx	Synchronous BBC
3	45	Breast	Basal-like	T3N0M0	2 years	Contralateral breast	Basal-like	T1N0Mx	Metachronous BBC
4	46	Breast	HER2-enriched	T2N1M0	3 years	Contralateral breast	Basal-like	T2N0Mx	Metachronous BBC
5	41	Breast	Basal-like	T3N1M0	4 years	Liver	Mucinous adenocarcinoma	/	Metastatic breast cancer
6	49	Breast	HER2-enriched	T2N2M0	6 months	Liver	Adenocarcinoma	/	Metastatic breast cancer

BBC, bilateral breast cancer.