Table A2.

Summary of studies included in breast carcinoma

Estimates	Studies	Ref. No.	Design		Country		Quality
Ever vs. Never
98	98	(38–135)	Cohort	12	HIC	72	AQ	66
			Case–control	86	LMIC	26	IQ	32
<6 months vs. Never
39	39	(39,40,42,48,51,53,56,57,59,60,62,66,69,71,74,78,80,83,85,88,92,93,95,96,98,99,105,107,110,112,114–116,119–121,135,211,212)	Cohort	7	HIC	33	AQ	32
			Case–control	32	LMIC	6	IQ	7
6–12 months vs. Never
36	36	(39,42,48,51,56,57,59,60,62,63,66,69,71,74,78,80,83,85,88,93,95,96,98,99,105,107,110,112,114–116,119–121,135,211)	Cohort	7	HIC	31	AQ	31
			Case–control	29	LMIC	5	IQ	5
>12 months vs. Never
50	50	(38–40,42,48,51,56,57,59–67,69,71,74,78–80,82,83,85,88,93,95,96,98,99,101,105,107,110,112–116,119–121,125–127,131,135,211)	Cohort	8	HIC	43	AQ	41
			Case–control	42	LMIC	7	IQ	9

HIC, high-income country; LIC, low-income country; AQ, adequate quality; IQ, inadequate quality.