At present, there is an ongoing conflict about the usefulness of breast cancer detection programmes and campaigns against breast cancer-attributed mortality. Breast cancer is one of the most frequent cancers in women in Europe1, and is also one of the most common causes of cancer mortality. Approximately 10,500 new cases of female breast cancer were diagnosed in Belgium in 20202.
The Flemish breast cancer screening programme was started in 2001 due to mounting evidence that breast cancer mammography screening reduces breast cancer-associated mortality as reported by many randomised controlled trials, such as the study by Nyström and colleagues3. As a result of the predominantly positive results arising from these studies, breast cancer screening programmes were established in many countries across the world. However, while the majority of these studies report a significant decrease in breast cancer-associated mortality in women that attended mammographic screening programmes (MSP), the impact ranges of these screening programmes vary drastically. For example, a study which assessed the efficacy of attendance at organised MSPs on breast cancer-associated mortality found a reduction in this mortality of between 12 and 58% in Western European women4. A recent Belgian study carried out by De Troeyer and colleagues examined the link between breast cancer-specific death and MSP participation. This study concluded that women who participated in breast cancer screening programmes had a 51% lower risk of breast cancer-specific mortality5.
In Belgium, the impact of breast cancer MSPs on breast cancer-specific mortality has not been assessed to date. Thus, this Belgian study by De Troeyer and colleagues published in Cancer Epidemiology in February 2023 aimed to address this gap in current knowledge. The benefit of this case-referent study over other observational studies was that the authors were able to assess additional impacts of MSP participation that went beyond routine care including opportunistic detection and clinical diagnosis, given the high opportunistic mammography rate in the population assessed in Flanders.
This study investigated the impact of participation in MSPs on 1571 breast cancer-attributed mortality cases from 2005 to 2017 as compared to 6284 randomly selected referents. Following multiple logistic regression model analysis, the correlation between breast cancer-attributed mortality and MSP participation in the four years prior to (pseudo)diagnosis was assessed. Data were stratified for age and adjusted for confounders including socio-economic position and calendar year of diagnosis. Of note, a large proportion of these cases had advanced disease at the time of diagnosis with 35% of cases reported as being stage IV.
Following adjustment, this study reported a 51% lower risk of breast cancer-attributed mortality in women who had participated in the Flemish MSP versus those who had not, and sensitivity analyses did not significantly change these estimated associations.
The authors conclude that participation in MSPs significantly reduces the risk of breast cancer-attributed mortality in this Flemish cohort with high opportunistic screening rates. However, the potential caveats of overdiagnosis and overtreatment should also be balanced with the findings of this study. This study supports existing evidence of potential benefit of attending an MSP on breast cancer-attributed mortality.
1: Dyba T, Randi G, Bray F, et al. The European cancer burden in 2020: Incidence and mortality estimates for 40 countries and 25 major cancers. Eur J Cancer. 2021 Nov;157:308-347. doi: 10.1016/j.ejca.2021.07.039. Epub 2021 Sep 21. PMID: 34560371; PMCID: PMC8568058.
3. Nyström L, Rutqvist LE, Wall S, et al. Breast cancer screening with mammography: overview of Swedish randomised trials. Lancet. 1993 Apr 17;341(8851):973-8. doi: 10.1016/0140-6736(93)91067-v. Erratum in: Lancet 1993 Nov 27;342(8883):1372. PMID: 8096941.
4. Zielonke N, Gini A, Jansen EEL, et al; EU-TOPIA consortium. Evidence for reducing cancer-specific mortality due to screening for breast cancer in Europe: A systematic review. Eur J Cancer. 2020 Mar;127:191-206. doi: 10.1016/j.ejca.2019.12.010. Epub 2020 Jan 10. PMID: 31932175.
5. De Troeyer K, Silversmit G, Rosskamp M, et al. The effect of the Flemish breast cancer screening program on breast cancer-specific mortality: A case-referent study. Cancer Epidemiol. 2023 Feb;82:102320. doi: 10.1016/j.canep.2022.102320. Epub 2023 Jan 4. PMID: 36608495.