Parenchymal pattern in women with dense breasts. Variation with age
and impact on screening outcomes: observations from a UK
Received: 11 December 2017 /Revised: 21 February 2018 /Accepted: 8 March 2018
European Society of Radiology 2018
Objectives To assess patterns of parenchymal tissue on mammographyinwomenwithdensebreastsandtodetermine
how this varies with age and affects recall to assessment and cancer diagnosis.
Method Breast density data was obtained in women attending routine mammographic screening from April 2013 to
March 2015 using automated breast density assessment software. Women with the densest breasts were selected for
visual interpretation of parenchymal pattern (PP). One hundred non-assessed women, aged 50, 55, 60, 65 and 69-71
years (total = 500), provided controls. Cases included women recalled for assessment (mastectomy or implants
excluded) (total = 280). Mammograms reviewed by ten readers and PP classified as: (1) very smooth; (2) mainly
smooth; (3) mixed; (4) mainly nodular; (5) very nodular. The ratio of women in each category at each age and
screening outcomes were compared by Pearson’s chi-squared test.
Results Reader agreement for scoring PP was good (intraclass correlation = 0.6302). Proportions of women in each PP category
were similar at all ages for controls (p = 0.147) and cases (p = 0.657). The ratio of PP categories did not vary significantly with
age in those who underwent biopsy (p = 0.484). Thirty-four cancers were diagnosed. There was a significant correlation between
a diagnosis of cancer and nodular PP compared to not nodular PP (p =0.043).
Conclusions The ratio of smooth to nodular pattern in women with the densest breasts did not vary with age. The PP of the breast
tissue did not affect likelihood of recall to assessment or biopsy. There was a significant relationship between a nodular
parenchymal pattern and diagnosis of cancer.
• This paper shows that there is good agreement between mammogram readers when classifying mammographic PP on a five-
point scale from very smooth to very nodular.
• In non-assessed women with the densest breasts, there is no significant change in the proportions of smooth to nodular patterns
with increasing age.
• The likelihood of recall for further assessment or biopsy at assessment is not related to PP in women with highest breast density.
• When recalled for further assessment, significantly more women are diagnosed with cancer in the group with nodular PP on
mammography when compared with smooth and mixed patterns.
Keywords Breast cancer
ICC Interclass correlation
NBSS National Breast Screening System
PP Parenchymal pattern
VGd Volpara Grade d
* Laura Ward
Department of Radiology, St George’s University Hospitals NHS
Foundation Trust, Blackshaw Road, London SW17 0AP, UK
New York University School of Medicine, New York, NY, USA