Two common genetic variants increase susceptibility to breast cancer in the Spanish population.

11092 Background: Breast cancer is the most common cause of death by cancer in women in Spain. Epidemiology clearly shows that genetic factors are significant components of risk even in women without detectable BRCA1 or BRCA2 germline mutations. We aim to detect genetic variants associated with breast cancer susceptibility in Spain.,Within a multinational genome-wide association study conducted in collaboration with Decode genetics, including 4,554 consenting patients diagnosed with breast cancer and 17,577controls, Spain contributed with 455 patients and 1,002 controls. >300,000 polymorphisms have been assessed with the Infinium II method (Illumina platform).,Two common genetic variants associated to breast cancer have been identified. One of them (rs 13387042A) is located in 2q35. Frequency in Spain (cases/controls/relative risk/2-tailed p) is 58.1%/53.3%/1.21/0.01. In the whole multinational study, relative risk/2-tailed p is 1.20/1.3×10-13. A second variant is located in 16q12 (rs3803662T). Frequency in Spain (cases/controls/relative risk/2-tailed p) is 34.8%/30.8%/1.20/0.03. In the whole multinational study, relative risk/2-tailed p is 1.28/5.9×10-19. Taken together, the estimated populational attributtable risk is 25.4%. The second variant is located adjacent to the TNRC9 gene. Both variants are associated with estrogen-positive breast cancer. The implications of these findings will be presented.,Two frequent genetic variants are associated with susceptibility to estrogen receptor positive breast cancer in the Spanish population. They are involved in 25.4% of all cases of this neoplasm in Spain. No significant financial relationships to disclose.