Personalized Breast Cancer Screening: A Risk Prediction Model Based on Women Attending BreastScreen Norway

Abstract

Background: We aimed to develop and validate a model predicting breast cancer risk for women targeted by breast cancer screening. Method: This retrospective cohort study included 57,411 women screened at least once in BreastScreen Norway during the period from 2007 to 2019. The prediction model included information about age, mammographic density, family history of breast cancer, body mass index, age at menarche, alcohol consumption, exercise, pregnancy, hormone replacement therapy, and benign breast disease. We calculated a 4-year absolute breast cancer risk estimates for women and in risk groups by quartiles. The Bootstrap resampling method was used for internal validation of the model (E/O ratio). The area under the curve (AUC) was estimated with a 95% confidence interval (CI). Results: The 4-year predicted risk of breast cancer ranged from 0.22–7.33%, while 95% of the population had a risk of 0.55–2.31%. The thresholds for the quartiles of the risk groups, with 25% of the population in each group, were 0.82%, 1.10%, and 1.47%. Overall, the model slightly overestimated the risk with an E/O ratio of 1.10 (95% CI: 1.09–1.11) and the AUC was 62.6% (95% CI: 60.5–65.0%). Conclusions: This 4-year risk prediction model showed differences in the risk of breast cancer, supporting personalized screening for breast cancer in women aged 50–69 years.

Breast Cancer Risk Factors among Women with Solid Breast Lesions

“…However, they should not be discarded as multiple studies have shown them to be linked to an increased risk of breast cancer [ 6 , 20 ]. Early menarche and late menopause (prolonged exposure to estrogen) were shown to be significant risk factors for breast cancer development [ 21 , 32 , 65 ]. On the other hand, early full-term pregnancy and prolonged breastfeeding were shown to be protective factors, decreasing the risk of breast cancer development [ 21 , 66 ].…”

“…Early menarche and late menopause (prolonged exposure to estrogen) were shown to be significant risk factors for breast cancer development [ 21 , 32 , 65 ]. On the other hand, early full-term pregnancy and prolonged breastfeeding were shown to be protective factors, decreasing the risk of breast cancer development [ 21 , 66 ]. Both in our results and in other existing published literature, smoking was not shown to be of statistical relevance regarding an increase in breast cancer risk [ 19 , 22 ].…”

“…On the other hand, protective factors against breast cancer were also identified. These include prolonged breastfeeding (>1 year), higher number of births and late menarche combined with early menopause (shortened period of exposure to estrogens) [ 3 , 21 ]. In the case of other factors, such as smoking status [ 19 , 22 ], the use of combined oral contraceptives and age at first birth, the influence is disputed [ 4 , 23 , 24 ].…”