title: Women with endometriosis have a higher DNA repair capacity and diminished breast cancer risk.
abstract: BACKGROUND
  Breast cancer (BC) and endometriosis are important reproductive health diseases for women. Although endometriosis is not a malignant condition, some of its characteristics mimic that of a malignancy. Endometriosis is associated with increased risk of certain cancers; however, whether it alters BC risk is unclear. This study evaluates the association of endometriosis and BC and explores whether DNA repair capacity (DRC) plays a role in such a relationship.
  
  
  METHODS
  A case-control study of 991 women (385 with BC and 606 controls, all recruited over 5 years) was undertaken in Puerto Rico. Eighty participants with self-reported surgically diagnosed endometriosis were identified, 20 of whom also had a diagnosis of BC. Data from a structured questionnaire and DRC measurements were assessed to determine the association between BC, DRC, and endometriosis.
  
  
  RESULTS
  Participants with BC cases were 50% less likely to have history of endometriosis (OR = 0.5 95%CI: 0.3, 0.9,p= 0.038) than women without BC controls. Findings that did not reach statistical significance included the following: women with history of endometriosis had a slightly higher DRC level than those without it; BC cases and history of endometriosis were less likely to have had endometriosis diagnosis before age 38 as compared to controls with endometriosis.
  
  
  CONCLUSIONS
  Here we report an inverse association between endometriosis and BC, the former possibly conferring a protective effect on the latter. Although the mechanisms involved are unknown they may include protection provided by higher DRC and or hormonal treatments for endometriosis. A larger sample of endometriosis cases is necessary to confirm these results and answer the question of whether a higher DRC capacity may contribute to this potential protection, and to identify other factors at play.
authors.affiliation: Department of Physiology and Pharmacology, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico.
authors.forename: Jaime L
authors.initials: JL
authors.lastname: Matta
authors.affiliation: Department of Microbiology, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico.
authors.forename: Idhaliz
authors.initials: I
authors.lastname: Flores
authors.affiliation: Department of Physiology and Pharmacology, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico ; Public Health Program, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico.
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Morales
authors.affiliation: Department of Biochemistry, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico.
authors.forename: Janice
authors.initials: J
authors.lastname: Monteiro
authors.affiliation: Department of Physiology and Pharmacology, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico ; Department of Microbiology, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico ; Public Health Program, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico.
authors.forename: Carolina
authors.initials: C
authors.lastname: Alvarez-Garriga
authors.affiliation: Department of Physiology and Pharmacology, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico ; Department of Microbiology, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico ; Public Health Program, Ponce School of Medicine and Health Sciences, Ponce, Puerto Rico.
authors.forename: Manuel
authors.initials: M
authors.lastname: Bayona
keywords: DNA repair capacity; breast cancer; endometriosis; risk factors