Treatment of Ductal Carcinoma in situ: A Register-Based Study of Norwegian Women Diagnosed between 1995 and 2018

Helle Kristine Skjerven; Anders Skyrud Danielsen; Ellen Schlichting; Kristine Kleivi Sahlberg; Solveig Hofvind

doi:10.1159/000524564

Treatment of Ductal Carcinoma in situ: A Register-Based Study of Norwegian Women Diagnosed between 1995 and 2018

Breast Care (Basel). 2022 Oct;17(5):486-494. doi: 10.1159/000524564. Epub 2022 Apr 21.

Authors

Helle Kristine Skjerven^{1

2}, Anders Skyrud Danielsen^{3

4}, Ellen Schlichting⁵, Kristine Kleivi Sahlberg⁶, Solveig Hofvind^{3

7}

Affiliations

¹ aSection for Breast and Endocrine Surgery Department, Vestre Viken Hospital Trust, Drammen, Norway.
² bSection for Breast Surgery, Vestfold Hospital Trust, Tonsberg, Norway.
³ cSection for Breast Cancer Screening, Cancer Registry of Norway, Oslo, Norway.
⁴ dDepartment of Microbiology, Oslo University Hospital, Oslo, Norway.
⁵ eSection for Breast and Endocrine Surgery, Oslo University Hospital, Oslo, Norway.
⁶ fDepartment of Research and Innovation, Vestre Viken Hospital Trust, Drammen, Norway.
⁷ gDepartment of Health and Care Sciences, The Arctic University, UiT, Tromsø, Norway.

Abstract

Introduction: The incidence of ductal carcinoma in situ (DCIS) has increased after implementation of mammographic screening. The lesion represents management challenges due to its undetermined growth pattern. We aimed to explore treatment of women aged 48-71 years diagnosed with DCIS between 1995 and 2018, by detection mode and histopathological characteristics.

Material and methods: Data on surgical treatment and radiation therapy (RT) of 4,995 women diagnosed with DCIS were retrieved from the Cancer Registry of Norway. We described the percentage and frequency of breast-conserving treatment (BCT) for participants in BreastScreen Norway (screen-detected) and nonparticipants. We estimated the relative risk (RR) of BCT, using log-binomial regression models.

Results: Use of BCT increased from about 40% in 1995 to 85% in 2018. Use of BCT was more common among older than younger women and more commonly used for screen-detected versus tumors detected outside the screening program. Nine out of ten women with tumors ≤10 mm were treated with BCT and two out of ten with tumors >50 mm. RT was given to 89.3% of the women with tumors ≤10 mm, 34.1% of those with tumors classified as van Nuys' grade 1 and <10 mm and 96.0% of the tumors >50 mm. Use of BCT was less common for tumors >50 mm compared to <10 mm (RR adjusted for age, detection mode, van Nuys' grade, and localization: 0.26, 95% CI: 0.19-0.36).

Conclusion: BCT was increasingly used among women diagnosed with DCIS in Norway during the period from 1995 to 2018, particularly for screen-detected, small lesions with low van Nuys' grade.

Keywords: Breast-conserving treatment; Ductal carcinoma in situ; Mastectomy; Oncoplastic surgery; Surgery.

Grants and funding

H.K.S. is partly funded by the Norwegian Women's Public Health Association (NKS), project #40109. The study is performed as a part of the other authors' regular work. The study did not receive any support from industry.