Appendix A3. Quality of Studies Assessing the Association Between XRCC1 Arg194Trp Polymorphism and Breast Cancer ^a,b.

Study (year)	Source of Control	Population Ethnicity	Sample Size	Menopausal Status	HWE Reported
Duell (2001)	+	+	+	A	+
Kim (2002)	+	-	+	+	+
Han (2003)	+	B	+	C	+
Smith (2003)	+	+	+	-	+
Smith (2003)	+	+	+	-	+
Moullan (2003)	+	-	+	-	+
Forsti (2004)	+	-	+	-	+
Deligezer (2004)	-	-	+	-	+
Chacko (2005)	+	-	+	+	+
Shen (2005)	+	A	+	+	+
Patel (2005)	+	BD	+	+	+
Pachkowski (2006)	+	+	+	-	+
Thyagarajan (2006)	+	-	+	-	+
Brewster (2006)	+	+	+	C	+
Zhang (2006)	+	+	+	+	+
Silva (2007)	+	+	+	+	+
Smith (2008)	+	+	+	-	+
Sangrajrang (2008)	+	-	+	+	+
Mitra (2008)	E	+	+	D	+
Loizidou (2008)	E	+	+	-	+
Sobczuk (2009)	-	-	+	+	+
Zipprich (2010)	+	D	+	C	+
Ming-Shiean (2010)	+	-	+	-	+
Sterpone (2010)	E	+	+	-	+
Liu (2011)	+	+	+	-	+
Przybylowska-Sygut (2013)	+	-	+	-	+
Al Mutairi (2013)	+	D	+	-	+
Ding (2014)	+	+	+	-	+
McCullough (2014)	+	B	+	+	+
Ramadan (2014)	+	-	+	A	+
Smolarz (2014)	+	-	+	-	+
Macias-Gomez (2015)	-	-	+	-	+

^a Definitions:Year, year of publication; positive sign (+), mentioned in the articles; negative sign (-), not mentioned in the article; Source of control means clinic (or hospital) based or population based; Population ethnicity means Caucasian, African-American and other ethnicity; sample size means calculable sample size; Menopausal status means adjustment of menopausal status (post, pre or both) for final measure of association using methods such as adjustment inregression models, restriction, stratification etc; HWE (Hardy Weinberg equilibrium) means calculated or reported HWE equilibrium.

^b A, Calculated OR for different strata, but data not shown; B, Only mentioned to ethnicity without adjustment; C, Adjusted, but no detail presented; D, Matched controls, but no detail presented; E, Source of controls: volunteers.