Mammographic percent density (MD) is recognized as one of the strongest risk factors associated with breast cancer. This matched case-control study investigated whether MD represents an independent risk factor. Mammograms were obtained from 1025 breast cancer patients and from 520 healthy controls. MD was measured using a quantitative computer-based threshold method (0-100%). Breast cancer patients had a higher MD than healthy controls (38 vs. 32%, P<0.01). MD was significantly higher in association with factors such as age over 60 years, body mass index (BMI) of 25-30 kg/m², nulliparity or low parity (one to two births). Average MD was inversely associated with age, BMI, parity and positively associated with age at first full-term pregnancy. MD was higher in women with at least one first-degree relative affected, but only among patients and not in the group of healthy controls (P<0.01/P=0.61). In women with an MD of 25% or more, the risk of breast cancer was doubled compared with women with an MD of less than 10% (odds ratio: 2.1; 95% confidence interval: 1.3-3.4; P<0.01); in the postmenopausal subgroup, the risk was nearly tripled (odds ratio: 2.7; 95% confidence interval: 1.6-4.7; P<0.001). This study provides further evidence that MD is an important risk factor for breast cancer. These results indicate strong associations between MD and the risk of breast cancer in a matched case-control study in Germany.

!Objective: The etiology of endometriosis is still a research field in which few consistent data are available. Large case-control studies or even cohort studies are rare, and most of the published data are conflicting. The aim of the present study was therefore to examine common epidemiological and endometriosis-specific risk factors in a German case-control study. Design: From 2001 to 2010, a pool of 595 laparoscopically confirmed cases and 475 controls were recruited in a hospital-based setting. After matching for age, 298 cases and 300 controls remained in the pool. Age at menarche, menstrual cycle length, duration of menstrual bleeding, number of pregnancies, live births, miscarriages, use of contraceptive pills, body mass index (BMI), and smoking status were analyzed with logistic regression models predicting endometriosis casecontrol status. Results: Menstrual cycle length, duration of menstrual bleeding, number of pregnancies, number of miscarriages, and smoking status, as relevant predictors for endometriosis case-control status, were identified as risk factors for endometriosis. Other factors such as age at menarche, number of live births, ever having used contraceptive pills, and BMI were not predictive. Conclusions: This hospital-based case-control study reproduced most of the familiar risk factors.Comparison of this study with others reveals a wide variety of effect sizes and directions of association with risk factors and may increase the information available about the characteristics of the patient population being treated in the relevant hospital setting.

No abstract