Hormone receptor status of a first primary breast cancer predicts contralateral breast cancer risk in the WECARE study population

Table 4 Association between hormone receptor status of first breast cancer and subtype-specific contralateral breast cancer

	ER+/PR+ CBC		ER+/PR- CBC		ER-/PR- CBC
Tumor status at first diagnosis	N (cases/controls)	RR^a (95% CI)	N (cases/controls)	RR^a (95% CI)	N (cases/controls)	RR^a (95% CI)
ER status
Positive	365/421	1.0 (ref.)	123/147	1.0 (ref.)	89/241	1.0 (ref.)
Negative	95/182	0.6 (0.4, 0.9)	55/67	0.9 (0.5, 1.6)	187/112	3.9 (2.4, 6.5)
Other/unknown^b	74/80		16/42		31/55
PR status
Positive	321/386	1.0 (ref.)	109/130	1.0 (ref.)	81/214	1.0 (ref.)
Negative	106/184	0.8 (0.6, 1.1)	52/63	0.9 (0.5, 1.5)	183/115	3.8 (2.3, 6.3)
Other/unknown^b	107/113		33/63		43/79
Joint ER/PR status
ER+/PR+	307/343	1.0 (ref.)	97/112	1.0 (ref.)	64/193	1.0 (ref.)
ER+/PR-	30/50	0.7 (0.4, 1.2)	14/15	1.2 (0.5, 2.7)	20/28	2.6 (1.1, 5.7)
ER-/PR-	74/130	0.7 (0.5, 1.0)	38/48	0.8 (0.4, 1.5)	162/83	5.4 (3.0, 9.5)
Other/unknown^b,c	123/160		45/81		61/104

Abbreviations: CBC contralateral breast cancer, RR risk ratio, CI confidence interval, N number, ER estrogen receptor, PR progesterone receptor
^aAdjusted for age at first breast cancer diagnosis, first-degree family history of breast cancer, histologic assessment, menopausal status, age at menarche, parity, radiation, chemotherapy and hormone therapy at first breast cancer diagnosis. ^b“Other/unknown” category consists of women for whom no laboratory test was given, the test was given and the results are unknown or the test was given and the results were borderline; estimates not reported. ^cIncludes tumors classified as ER-/PR+

ISSN: 1465-542X