title: Positive predictive values by mammographic density and screening mode in the Norwegian Breast Cancer Screening Program.
abstract: OBJECTIVE
  To investigate the probability of breast cancer among women recalled due to abnormal findings on the screening mammograms (PPV-1) and among women who underwent an invasive procedure (PPV-2) by mammographic density (MD), screening mode and age.
  
  
  METHODS
  We used information about 28,826 recall examinations from 26,951 subsequently screened women in the Norwegian Breast Cancer Screening Program, 1996-2010. The radiologists who performed the recall examinations subjectively classified MD on the mammograms into three categories: fatty (<30% fibroglandular tissue); medium dense (30-70%) and dense (>70%). Screening mode was defined as screen-film mammography (SFM) and full-field digital mammography (FFDM). We examined trends of PPVs by MD, screening mode and age. We used logistic regression to estimate odds ratio (OR) of screen-detected breast cancer associated with MD among women recalled, adjusting for screening mode and age.
  
  
  RESULTS
  PPV-1 and PPV-2 decreased by increasing MD, regardless of screening mode (p for trend <0.05 for both PPVs). PPV-1 and PPV-2 were statistically significantly higher for FFDM compared with SFM for women with fatty breasts. Among women recalled, the adjusted OR of breast cancer decreased with increasing MD. Compared with women with fatty breasts, the OR was 0.90 (95% CI: 0.84-0.96) for those with medium dense breasts and 0.85 (95% CI: 0.76-0.95) for those with dense breasts.
  
  
  CONCLUSIONS
  PPVs decreased by increasing MD. Fewer women needed to be recalled or undergo an invasive procedure to detect one breast cancer among those with fatty versus dense breasts in the screening program in Norway, 1996-2010.
authors.affiliation: Cancer Registry of Norway, Oslo, Norway. Electronic address: Nataliia.Moshina@kreftregisteret.no.
authors.forename: Nataliia
authors.initials: N
authors.lastname: Moshina
authors.affiliation: Cancer Registry of Norway, Oslo, Norway; Institute of Basic Medical Sciences, Medical Faculty, University of Oslo, Oslo, Norway; Department of Preventive Medicine, University of Southern California, CA, USA. Electronic address: Giske.Ursin@kreftregisteret.no.
authors.forename: Giske
authors.initials: G
authors.lastname: Ursin
authors.affiliation: Cancer Registry of Norway, Oslo, Norway; Department of Women and Children's Health, Oslo University Hospital, Oslo, Norway. Electronic address: Marta.Roman@kreftregisteret.no.
authors.forename: Marta
authors.initials: M
authors.lastname: Roman
authors.affiliation: Cancer Registry of Norway, Oslo, Norway. Electronic address: Sofie.Sebuodegard@kreftregisteret.no.
authors.forename: Sofie
authors.initials: S
authors.lastname: Sebuødegård
authors.affiliation: Cancer Registry of Norway, Oslo, Norway; Oslo and Akershus University College of Applied Sciences, Faculty of Health Science, Oslo, Norway. Electronic address: Solveig.Hofvind@kreftregisteret.no.
authors.forename: Solveig
authors.initials: S
authors.lastname: Hofvind
mesh_terms: D000367:Age Factors; D000368:Aged; D000071060:Breast Density; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D042361:Mammary Glands, Human / Q000002:abnormalities*; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009664:Norway; D011237:Predictive Value of Tests; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results
keywords: Breast cancer screening; Mammographic density; Positive predictive value; Screening mode