Can population breast screening programs be leveraged to reduce the burden of breast cancer?

Abstract

Breast cancer (BC) is the most common cancer in women. A study of the temporal trends (1998–2012) in the age-standardised incidence rate in 41 countries showed that increased BC incidence rates had occurred in pre- and post-menopausal women [[1]Heer E. Harper A. Escandor N. Sung H. McCormack V. Fidler-Benaoudia M.M. Global burden and trends in premenopausal and postmenopausal breast cancer: a population-based study.Lancet Global Health. 2020; 8: e1027-e1037Abstract Full Text Full Text PDF PubMed Scopus (207) Google Scholar]. However, increases exclusively in premenopausal ages were observed mainly in high-income countries, whereas the largest increases in the incidence of postmenopausal BC were observed predominantly in countries undergoing socioeconomic transitions. These findings probably reflect changes in the prevalence of various lifestyle factors that are known to increase BC risk, many of which are inherent in the social and economic circumstances of a population. Although many of these factors, such as reproductive history, alcohol, and (lack of) physical activity, are associated with BC risk across the lifespan, some, for example body fat/obesity and weight gain in adulthood, are associated with post-menopausal BC [[2]World Cancer Research Fund/American Institute for Cancer ResearchDiet, nutrition, physical activity and cancer: a global perspective. Continuous update project expert report 2018.2018Google Scholar]. Mammography screening reduces the risk of BC death through detection and treatment of early-stage disease. Population-based programs have been providing mammography screening to women aged ≥40 years for decades, but screening represents secondary prevention so cannot curb the growing incidence of BC. The interplay of BC risk factors throughout an individual's lifetime renders primary prevention difficult at a population level. Therefore, prevention efforts have focused on subgroups at substantially increased BC risk in whom effective strategies, such as risk-reducing surgery or chemoprevention, may be appropriate. Neither of these strategies can be recommended to the majority of women who are at average BC risk or thereabouts, who routinely present for screening. Contemplation of a new approach to screening, namely risk-stratified screening, has progressed to formal trialling and includes an element of prevention for those at increased BC risk [[3]Pashayan N. Antoniou A.C. Ivanus U. et al.Personalized early detection and prevention of breast cancer: ENVISION consensus statement.Nat Rev Clin Oncol. 2020; 17: 687-705Crossref PubMed Scopus (76) Google Scholar,[4]Esserman L.J. WISDOM Study and Athena InvestigatorsThe WISDOM Study: breaking the deadlock in the breast cancer screening debate.NPJ Breast Cancer. 2017; 3: 34Crossref PubMed Google Scholar]. While results from risk-stratified screening trials are awaited, BC screening programs could be leveraged from now to explore primary prevention in the broader female population participating at periodic intervals and starting screening at an age potentially amenable to lifestyle-related prevention. The development, evaluation, and uptake of lifestyle-related (prevention) interventions will prove to be challenging and would require additional investments to be integrated into existing screening programs, however this approach has the potential to be offered to all screening program participants. Most BC screening programs have data collection and follow-up processes to monitor outcomes which could be expanded to capture data on lifestyle-related risk factors (eg BMI). Program-embedded pilot studies could be established as a first step to investigate the feasibility of integrating primary prevention strategies alongside mammography screening and to assess specific interventions. Consensus on meaningful surrogate outcomes would be needed because changes in incidence, or mortality outcomes, require 10–20 years or longer to be observed. Essential to this proposed approach is funding and a broadly collaborative approach between population screening programs, BC stakeholders including consumers and researchers, and co-designed interventions to ensure acceptability to women and cultural appropriateness. None to declare. I receive research funding via the NBCF Chair in Breast Cancer Prevention (grant #EC-21-001).