Screening is associated with lower mastectomy rates in eastern Switzerland beyond stage effects

Breast cancer in Switzerland: a comparison between organized-screening versus opportunistic-screening cantons

BACKGROUND

Switzerland is one of the few remaining European countries without a uniform national breast cancer screening program. Most Swiss cantons have initiated mammography screening programs, with the notable exceptions of the cantons of central Switzerland. The aim of this study is to compare the TNM (tumor-node-metastasis) status in woman diagnosed with screen- and non-screen-detected breast cancers. We compare TNM of breast cancers of cantonal screening cantons (Or-SC) with organized mammographic screening and opportunistic-screening cantons (Op-SC) without organized mammographic screening.

MATERIALS AND METHODS

We compared the TNM documented in cantons with organized screening (Or-SC) in the national cancer registry with those in the cantons of central Switzerland without organized screening (Op-SC) between 2014 and 2020. Since 2014, a total of 19 236 patients from Or-SC and 2282 from Op-SC with breast cancer were compared. Age groups were defined as younger than 50 years, between 50 and 69 years, and older than 70 years.

RESULTS

By comparison, women aged 50-69 years in the cantons of the Op-SC group exhibited significantly larger tumors T1-3 [point estimate of the difference with 95% confidence interval (CI) for T1: -7.7% (95% CI -11.0% to -4.4%); T2: 5.3% (95% CI 2.2% to 8.5%); T3: 2.5% (95% CI 0.8% to 4.2%)] and significantly fewer proportion of N0 [-5.7% (95% CI -9.0% to -2.5%)] without significant difference in the M status (P = 0.97).

CONCLUSION

Our study shows that patients aged 50-69 years from Op-SC have significantly larger tumors and higher incidence of lymph node metastases than women in the corresponding Or-SC group. This globally unique case within one single small country with very high living standards, but with different screening strategies, indicates the benefits of organized breast screening programs.

[The possible benefit of artificial intelligence in an organized population-related screening program : Initial results and perspective]

BACKGROUND

Mammography screening programs (MSP) have shown that breast cancer can be detected at an earlier stage enabling less invasive treatment and leading to a better survival rate. The considerable numbers of interval breast cancer (IBC) and the additional examinations required, the majority of which turn out not to be cancer, are critically assessed.

OBJECTIVE

In recent years companies and universities have used machine learning (ML) to develop powerful algorithms that demonstrate astonishing abilities to read mammograms. Can such algorithms be used to improve the quality of MSP?

METHOD

The original screening mammographies of 251 cases with IBC were retrospectively analyzed using the software ProFound AI® (iCAD) and the results were compared (case score, risk score) with a control group. The relevant current literature was also studied.

RESULTS

The distributions of the case scores and the risk scores were markedly shifted to higher risks compared to the control group, comparable to the results of other studies.

CONCLUSION

Retrospective studies as well as our own data show that artificial intelligence (AI) could change our approach to MSP in the future in the direction of personalized screening and could enable a significant reduction in the workload of radiologists, fewer additional examinations and a reduced number of IBCs; however, the results of prospective studies are needed before implementation.

Comparison of the differential effect of participation in breast cancer screening program versus opportunistic screening or symptomatic detection on tumour characteristics

OBJECTIVES

The success of a breast cancer screening program is highly dependent on adherence. We aimed to compare the differential effect of participation in breast cancer screening program versus opportunistic screening or symptomatic detection on tumour characteristics.

METHODS

We included women referred to our Breast Centre in 2015-2021: 321 from the breast cancer screening group (group 1) and 422 through opportunistic screening or due to symptomatic detection (group 2). We compared data on sociodemographics, breast cancer detection, clinical features and tumour characteristics.

RESULTS

A total of 10.6% of women in group 1 had breast symptoms and 63.8% had breast signs, with group 2 presenting higher proportions (57.6 and 77.8%, respectively, P < 0.001). The median tumour size in group 1 was smaller compared with group 2 (14 vs 17 mm, P < 0.001). A total of 8.7% of women in group 1 had nodal involvement whereas in group 2 the proportion corresponded to 19.0% (P < 0.001). No women in group 1 were diagnosed with metastasis, while metastases were found in 2.4% of those from group 2 (P = 0.005). There were no significant differences in molecular subtype of invasive tumours between the two groups.

CONCLUSION

The tumour characteristics of women who participated in the breast cancer screening program showed in almost all characteristics more favourable results in comparison with the group who underwent opportunistic screening or sought care due to symptoms. The lower clinical stage observed in those referred from the organised program reaffirms that it is an effective measure for early detection, diagnosis, and treatment.

Breast cancer patients enrolled in the Swiss mammography screening program "donna" demonstrate prolonged survival

STUDY GOAL

We compared the survival rates of women with breast cancer (BC) detected within versus outside the mammography screening program (MSP) "donna".

METHODS

We merged data from the MSP with the data from corresponding cancer registries to categorize BC cases as within MSP (screen-detected and interval carcinomas) and outside the MSP. We analyzed the tumor stage distribution, tumor characteristics and the survival of the women. We further estimated hazard ratios using Cox-regressions to account for different characteristics between groups and corrected the survival rates for lead-time bias.

RESULTS

We identified 1057 invasive (ICD-10: C50) and in-situ (D05) BC cases within the MSP and 1501 outside the MSP between 2010 and 2019 in the Swiss cantons of St. Gallen and Grisons. BC within the MSP had a higher share of stage I carcinoma (46.5% vs. 33.0%; p < 0.01), a smaller (mean) tumor size (19.1 mm vs. 24.9 mm, p < 0.01), and fewer recurrences and metastases in the follow-up period (6.7% vs. 15.6%, p < 0.01). The 10-year survival rates were 91.4% for women within and 72.1% for women outside the MSP (p < 0.05). Survival difference persisted but decreased when women within the same tumor stage were compared. Lead-time corrected hazard ratios for the MSP accounted for age, tumor size and Ki-67 proliferation index were 0.550 (95% CI 0.389, 0.778; p < 0.01) for overall survival and 0.469 (95% CI 0.294, 0.749; p < 0.01) for BC related survival.

CONCLUSION

Women participating in the "donna" MSP had a significantly higher overall and BC related survival rate than women outside the program. Detection of BC at an earlier tumor stage only partially explains the observed differences.

Marrying Story with Science: The Impact of Outdated and Inconsistent Breast Cancer Screening Practices in Canada

Behind the science of breast cancer in Canada, as well as globally, are the stories of thousands of women, their families, and their communities. These include stories from those who have died or those suffering from the realities of stage III and stage IV breast cancer due to late detection, misinformation, and dismissal. The reality for these women is that, whilst grateful for the latest developments in cancer research, much of this knowledge is not reflected in policy and practice. Canadian guidelines do not reflect the recommended screening by experts within the field and inequities in screening practices and practitioner knowledge exist in different areas within Canada. Told through the stories of women with lived experiences of late-stage breast cancer and supported by scientific evidence, this paper explores the impact of outdated breast cancer screening practices on the lives of women. Recent patient advocacy is driving changes, such as notifying women of their breast density in a few jurisdictions in Canada, but we call for the whole medical community to take responsibility and ensure breast screening is optimised to save more lives.