Breast carcinoma detection modes and death in a female population in relation to population-based mammography screening

Comprehensive Inherited Risk Estimation for Risk-Based Breast Cancer Screening in Women

PURPOSE

Family history (FH) and pathogenic variants (PVs) are used for guiding risk surveillance in selected high-risk women but little is known about their impact for breast cancer screening on population level. In addition, polygenic risk scores (PRSs) have been shown to efficiently stratify breast cancer risk through combining information about common genetic factors into one measure.

METHODS

In longitudinal real-life data, we evaluate PRS, FH, and PVs for stratified screening. Using FinnGen (N = 117,252), linked to the Mass Screening Registry for breast cancer (1992-2019; nationwide organized biennial screening for age 50-69 years), we assessed the screening performance of a breast cancer PRS and compared its performance with FH of breast cancer and PVs in moderate- (CHEK2)- to high-risk (PALB2) susceptibility genes.

RESULTS

Effect sizes for FH, PVs, and high PRS (>90th percentile) were comparable in screening-aged women, with similar implications for shifting age at screening onset. A high PRS identified women more likely to be diagnosed with breast cancer after a positive screening finding (positive predictive value [PPV], 39.5% [95% CI, 37.6 to 41.5]). Combinations of risk factors increased the PPVs up to 45% to 50%. A high PRS conferred an elevated risk of interval breast cancer (hazard ratio [HR], 2.78 [95% CI, 2.00 to 3.86] at age 50 years; HR, 2.48 [95% CI, 1.67 to 3.70] at age 60 years), and women with a low PRS (<10th percentile) had a low risk for both interval- and screen-detected breast cancers.

CONCLUSION

Using real-life screening data, this study demonstrates the effectiveness of a breast cancer PRS for risk stratification, alone and combined with FH and PVs. Further research is required to evaluate their impact in a prospective risk-stratified screening program, including cost-effectiveness.

Proportion of women with self-reported opportunistic mammography before organized screening

BACKGROUND

In Finland, organized nationwide breast cancer (BC) screening is biennially offered for women aged 50-69 years. The aim was to estimate, for the first time in Finland, the proportion of women having opportunistic mammography at age less than 50 years and to investigate the role of BC family history and educational level for having opportunistic mammography.

MATERIAL AND METHODS

The study material comprises two self-administered, population-based questionnaires from altogether 9845 healthy women; 4666 women in Women's Health and Use of Hormone-study (WHH survey), and 5179 in Breast Cancer Screening, Lifestyle and Quality of Life-study (EET survey). We report the estimated proportions of women with self-reported opportunistic mammography at age <50 years in percentages.

RESULTS

The response percentages were 53% in the WHH survey and 52% in the EET survey. The percentage of women with self-reported opportunistic mammography was 66.7% and 60.4% in the two questionnaires, respectively. Regarding family history of BC, 76.5% and 68.5% of women with BC family history in a first degree relative reported having had a mammography, in contrast to that of 65.5% and 59.4% of women without BC family history. Opportunistic mammography was also more common in women with >12 years of education than women with ≤12 years of education.

DISCUSSION AND CONCLUSIONS

Overall, some two thirds of the women reports of having had a mammography before organized screening started. Opportunistic mammography was more likely among women with a positive family history of BC in a first degree relative as well as more than 12 years of education. Regardless of low response activity, the observed popularity of opportunistic mammography before organized screening gives ground for further evaluation of the related health care practices. Screening activity before organized screening also influences the evaluation of the screening program, as women have different, indeterminate histories of pre-organized screening.