Appendix A1. Details of Electronic Search Strategy ^a.

Database	Search Strategy	N
PubMed/NLM	(“Polymorphism”) AND (“Breast Neoplasms” OR “Breast Tumor” OR “Human Mammary Neoplasm” OR “Human Mammary Carcinoma” OR “Cancer of Breast” OR “Breast cancer” OR “Mammary Cancer” OR “Malignant Neoplasm of Breast” OR “Malignant Tumor of Breast” OR “Breast Carcinoma” OR “Cancer of the Breast” OR “Ductal carcinoma of breast” OR “Lobular Carcinoma of breast” OR “Medullary breast cancer” OR “Breast tumor” OR “In Situ breast cancer”)	5345
PMC/NLM	(“Polymorphism”[ti]) AND (“Breast Neoplasms” [ti] OR “Breast Tumor” [ti] OR “Human Mammary Carcinoma” [ti] OR “Cancer of Breast”[ti] OR “Breast cancer”[ti] OR “Mammary Cancer”[ti] OR “Malignant Neoplasm of Breast”[ti] OR “Malignant Tumor of Breast”[ti] OR “Breast Carcinoma”[ti] OR “Cancer of the Breast”[ti] OR “Ductal carcinoma of breast”[ti] OR “Lobular Carcinoma of breast”[ti] OR “Medullary breast cancer”[ti] OR “Breast tumor”[ti] OR “In Situ breast cancer”[ti])	138
ISI Web of Science/Thomson Reuters	(Polymorphism a breast cancer) Refined by: LANGUAGES: ( ENGLISH ) AND Databases: ( WOS ) AND RESEARCH AREAS: ( ONCOLOGY OR GENETICS HEREDITY OR BIOCHEMISTRY MOLECULAR BIOLOGY OR GERIATRICS GERONTOLOGY ) AND DOCUMENT TYPES: ( ARTICLE OR REVIEW OR CORRECTION ) Timespan: All years.	1501

^a Calculated OR for different strata, but data not shown.