Table 1.

Incidence and common sites of multiple primary malignancies after the first primary breast cancer

Authors	Years	Country	People count	Incidence rate(%)	Common sites
Ramin et al. [6]	2023	USA	16,004	9.7	Peritoneal cancer (SIR = 3.44), soft tissue sarcoma (SIR = 3.32), contralateral breast cancer (SIR = 3.44), myelodysplastic syndrome (SIR = 3.25), acute myeloid leukemia (SIR = 2.11)
Macq et al. [1]	2023	Belgium	149,530	10.1	Contralateral breast cancer (SIR = 2.14), esophageal cancer (SIR = 1.87), colorectal cancer (SIR = 1.4), lung cancer (SIR = 1.37), and renal cancer (SIR = 1.34)
Li et al. [8]	2020	USA	250 764	12	Contralateral breast cancer (5.2%), gastrointestinal tumors (1.7%), lung cancer (1.3%), female reproductive tract tumors (1.2%), and skin cancer (0.6%)
Parhizgar et al. [28]	2022	22 countries	91,678	NA*	Non-melanoma skin cancer (SIR = 2.87), bone and soft tissue sarcoma (SIR = 2.25), uterus (SIR = 1.98), ovary (SIR = 1.64), and thyroid (SIR = 1.56)
Zheng et al. [9]	2018	Sweden	87,752	17	Contralateral breast cancer (9.9%), colorectal cancer (1.8%), lung cancer (1.0%), endometrial cancer (0.8%), and melanoma (0.5%)
Baos et al. [7]	2021	USA	8616	NA*	Contralateral breast cancer (30%), lung cancer (13.4%), uterine corpus cancer (5.8%), thyroid cancer (5.6%), and cutaneous melanoma (4.5%)
Qian et al. [29]	2020	USA	208,474	8.9%	Contralateral breast cancer (3.0%), lung and bronchial cancer (1.2%), uterine corpus cancer (0.5%), cutaneous melanoma (0.4%), and thyroid cancer (0.3%)
Allen et al. [20]	2023	Global	NA**	NA*	Thyroid cancer (SIR = 1.89), endometrial cancer (SIR = 1.84), ovarian cancer (SIR = 1.53), kidney cancer (SIR = 1.43), and cutaneous melanoma (SIR = 1.34)

*NA: not explicitly mentioned in the literature

**NA: the paper is a meta-analysis with a wide range of inclusion