Table 2.

n-3 PUFA and breast cancer risk: Case-control studies.

Year	Country	Subjects Characteristics	Method of Assessment	n-3/n-6 PUFA Source	BC Risk	Reference
2007	Japan	103 incident BC cases 309 controls	erythrocyte membrane FFQ	dietary food intake including soy and meat products, fish and other seafood, vegetables	↑ dietary intake of n-3 fatty acids ↓ BC risk ↑ long chain n-3 PUFA in erythrocyte ↓ BC risk ↑ saturated fatty ↑ BC risk	[46]
2007	China	322 incident BC cases 1030 controls	erythrocyte membrane		↑ total n-3 fatty acids and EPA ↓ BC risk	[47]
2009	China	155 NPFC 1 185 PFC 2 241 BC, 1030 controls	erythrocyte membrane FFQ	dietary food intake	↑ EPA ↓ risk of NPFC ↓ progression of PFC to BC ↑ γ-linolenic acid ↑ risk of NPFC, PFC and BC	[38]
2002	US	73 BC patients 74 controls	breast adipose tissue		↑ EPA and DHA ↓ n-6/n-3 PUFA ratio ↓ BC risk ↑ n-6 PUFA ↑ BC risk	[18]
2003	US	565 incident BC 554 controls	FFQ	daily fat intake	↓ n-6/n-3 PUFA ratio ↓ BC risk (premenopausal) ↑EPA, DHA ↓ BC risk (21% and 18%, respectively)	[41]
2009	Denmark	463 BC cases 1098 controls	Gluteal adipose tissue biopsy	dietary food intake	No association between total or individual marine n-3 PUFA in adipose tissue and risk of BC	[44]
2002	France	241 invasive BC cases 88 controls-benign breast disease	breast adipose tissue		↑ ALA ↑ DHA ↓ n-6/n-3 PUFA ratio ↓ BC risk	[45]
2012	Mexican	1000 incident BC cases 1074 controls	Interview and FFQ	dietary food intake	↑ n-3 PUFA ↓ BC risk (obese women) ↑ n-6 PUFA ↑ BC risk (premenopausal)	[19]
2009	South Korea	358 incident BC patients 360 controls	FFQ	fatty and lean fish	↑ fatty fish consumption ↓ BC risk ↑EPA and DHA derived from fish ↓ BC risk	[39]

¹ Benign proliferative fibrocystic conditions (PFC); ² non-proliferative fibrocystic conditions (NPFC); ↑: increase; ↓: decrease.