Table 2.

Familial risk for second primary cancers among breast cancer patients

Site of second primary cancer	Breast cancer patients						P‐Trend
	Negative family history			Positive family history
	N	RR	95%CI	N	RR	95%CI
UAT	138	1.38	1.16‐1.64	5	2.31	0.96‐5.56	0.17
Esophagus	44	1.56	1.15‐2.11	0	‐	‐	‐
Stomach	93	1.37	1.11‐1.69	8	3.14	1.57‐6.28	0.003
Small intestine	46	1.54	1.14‐2.07	0	‐	‐	‐
Colorectum	683	1.17	1.08‐1.26	112a	1.50	1.25‐1.81	<0.001
Colon	499	1.16	1.06‐1.27	45	1.35	1.01‐1.81	<0.001
Rectum	233	1.15	1.01‐1.32	18	1.90	1.19‐3.01	<0.001
Anus	37	1.38	0.99‐1.92	0	‐	‐	‐
Liver	139	1.25	1.06‐1.49	7	2.54	1.21‐5.32	0.007
Pancreas	176	1.20	1.03‐1.39	9	2.35	1.22‐4.52	0.02
Nose	9	1.29	0.66‐2.51	0	‐	‐	‐
Lung	744	1.54	1.43‐1.66	96	2.93	2.40‐3.58	<0.001
Breast	6744	3.90	3.80‐4.00	1909b	4.89	4.67‐5.12	<0.001
Cervix	95	1.07	0.87‐1.31	2	1.58	0.39‐6.32	0.16
Endometrium	627	1.42	1.31‐1.54	37	3.32	2.40‐4.58	<0.001
Uterus	1	2.38	0.32‐17.49	0	‐	‐	‐
Ovary	364	1.49	1.34‐1.65	35	6.28	4.50‐8.75	<0.001
Other female genitals	53	1.09	0.83‐1.44	0	‐	‐	‐
Kidney	180	1.44	1.24‐1.68	7	2.12	1.01‐4.44	0.24
Bladder	189	1.30	1.12‐1.51	14	2.21	1.31‐3.74	0.005
Melanoma	423	1.32	1.19‐1.45	26	1.97	1.34‐2.89	<0.001
Skin (SCC)	339	1.35	1.21‐1.51	79c	3.47	2.78‐4.33	<0.001
Eye	25	1.42	0.95‐2.12	0
Nervous system	204	1.01	0.88‐1.17	6	1.16	0.52‐2.57	0.10
Thyroid gland	90	1.72	1.39‐2.12	1	2.73	0.38‐19.42	0.31
Endocrine gland	172	1.17	1.01‐1.37	8	3.50	1.75‐6.99	0.004
Bone	10	1.83	0.96‐3.48	0	‐	‐	‐
Connective tissue	66	2.15	1.67‐2.76	0	‐	‐	‐
Non‐Hodgkin lymphoma	224	1.21	1.05‐1.38	10	2.03	1.09‐3.77	0.01
Hodgkin lymphoma	15	1.29	0.77‐2.17	0	‐	‐	‐
Myeloma	79	1.06	0.85‐1.33	2	2.08	0.52‐8.31	0.15
Leukemia	222	1.38	1.20‐1.57	5	1.32	0.55‐3.17	0.18
CUP	253	1.37	1.21‐1.55	10	1.82	0.98‐3.38	0.01
All cancersd	4672	3.00	2.91‐3.09	10280	3.54	3.46‐3.62	<0.001
All cancerse	1905	1.25	1.19‐1.31	4394	1.53	1.49‐1.58	<0.001

For specific cancer as SPC, the reference group is the general population in the database had neither a family history of SPC nor BC (except for risk estimation of second BC), which is used to calculate the incidence of this specific cancer as first primary cancer.

UAT, upper aerodigestive tract; SCC, squamous cell carcinoma; CUP, cancer of unknown primary.

Bolding, italic and underlining indicate that the 95%CI, 99%CI and 99.9%CI did not overlap with 1.00 respectively.

^a12 of the 112 cases had only family history of in situ colorectal cancer.

^b100 of the 1909 cases had only family history of in situ BC.

^c41 of the 79 cases had only family history of in situ skin cancer.

^dBreast cancer is included into all cancers.

^eBreast cancer is excluded from all cancers.