Mariëtte Lokate, Petra HM Peeters,Linda M Peelen, Gerco Haars, Wouter B Veldhuis and Carla H van Gils. Mammographic density and breast cancer risk: the role of the fat surrounding the fibroglandular tissue. Breast Cancer Research, 2011 Dec 3;13(5):R103. Publisher full text
Study population [CLEAR SUBHEADING]
The study population comprises participants of the Prospect-EPIC study , which is a part of the EPIC-NL study . EPIC-NL is the Dutch contribution to the European Prospective Investigation into Cancer and Nutrition (EPIC) study [30,31]. The Prospect-EPIC participants were recruited through the breast cancer screening programme in Utrecht and vicinity... All participants gave their informed consent and the study was approved by The Institutional Review Board of the University Medical Centre Utrecht.
Mammographic density assessment [CLEAR SUBHEADING]
Mammographic density was assessed on the left mediolateral oblique mammograms (MLO) taken at the time of recruitment into the cohort...
For assessing the mammographic density, Cumulus software (University of Toronto, ON, Canada) was used . With this software, two thresholds were set by the reader; one to distinguish the breast area from the background and a second to distinguish the dense from the non-dense area... [ESTABLISHED METHOD]
Statistical analysis [CLEAR SUBHEADING]
Patient characteristics were described within quintiles of dense area and non-dense area among controls. For continuous variables we used means with standard deviations if normally distributed and medians with interquartile ranges of not normally distributed data (number of children). For categorical variables, we show proportions...
Correlations between density measures with BMI and each other are calculated using the Pearson correlation coefficient. The non-linear density measures were transformed using natural logarithm in order to get normally distributed measures...
All P-values are two-sided and if below 0.05 the results were considered statistically significant. Analyses were conducted using PASW Statistics 17.0 (SPSS, Inc., Chicago, IL, USA). [STATISTICAL TESTS AND PARAMETERS]