Impact of organized and opportunistic screening on excess mortality and on social inequalities in breast cancer survival

• Published in: International journal of cancer 2025-02, Vol.156 (3), p.518-528
• Main Authors: Poiseuil, Marie, Molinié, Florence, Dabakuyo‐Yonli, Tienhan Sandrine, Laville, Isabelle, Fauvernier, Mathieu, Remontet, Laurent, Amadeo, Brice, Coureau, Gaëlle
• Format: Article
• Language: English
• Subjects: Adult; Aged; Breast cancer; Breast Neoplasms - diagnosis; Breast Neoplasms - mortality; Cohort analysis; deprivation; Early Detection of Cancer - methods; excess mortality hazard; Female; Gays & lesbians; Humans; Mammography; Mass Screening - methods; Middle Aged; Mortality; opportunistic screening; organized screening; Population studies; Registries; Socioeconomic Factors; Statistics; Survival
• ISSN: 0020-7136; 1097-0215; 1097-0215
• DOI: 10.1002/ijc.35173

In most developed countries, both organized screening (OrgS) and opportunistic screening (OppS) coexist. The literature has extensively covered the impact of organized screening on women's survival after breast cancer. However, the impact of opportunistic screening has been less frequently described due to the challenge of identifying the target population. The aim of this study was to describe the net survival and excess mortality hazard (EMH) in each screening group (OrgS, OppS, or No screening) and to determine whether there is an identical social gradient in each groups. Three data sources (cancer registry, screening coordination centers, and National Health Data System [NHDS]) were used to identify the three screening groups. The European Deprivation Index (EDI) defined the level of deprivation. We modeled excess breast cancer mortality hazard and net survival using penalized flexible models. We observed a higher EMH for “No screening” women compared with the other two groups, regardless of level of deprivation and age at diagnosis. A social gradient appeared for each group at different follow‐up times and particularly between 2 and 3 years of follow‐up for “OrgS” and “OppS” women. Net survival was higher for “OrgS” women than “OppS” women, especially for the oldest women, and regardless of the deprivation level. This study provides new evidence of the impact of OrgS on net survival and excess mortality hazard after breast cancer, compared with opportunistic screening or no screening, and tends to show that OrgS attenuates the social gradient effect. What's new? Opportunistic screening for breast cancer typically is carried out at gynecological follow‐up, unlike organized screening, where women are invited to mammography and engage in follow‐up screening. This study compared the impacts of opportunistic, organized, and no screening on breast cancer mortality within the context of social inequality. A social gradient was observed, regardless of screening practice, but with variation in timing of impact. Social inequalities most affected women with no screening, with high excess mortality observed within 1 year of diagnosis, and were relevant for opportunistic screening between 2‐ and 5‐year follow‐up. Social inequality was least significant for organized screening.