The impact of lifecourse socio-economic position and individual social mobility on breast cancer risk

Eloïse Berger (1) , Noële Maitre (2) , Francesca Romana Mancini (2) , Laura Baglietto (2, 3) , Vittorio Perduca (2, 4) , Hélène Colineaux (1, 5) , S. Sieri (6) , Salvatore Panico (7) , Carlotta Sacerdote (8) , Rosario Tumino (9) , Paolo Vineis (10, 11) , Marie Christine Boutron-Ruault (2) , Gianluca Severi (2, 12) , Raphaële Castagné (1) , Cyrille Delpierre (1)

1 LEASP - Epidémiologie et analyses en santé publique : risques, maladies chroniques et handicaps
2 CESP - Centre de recherche en épidémiologie et santé des populations
3 University of Pisa - Università di Pisa
4 MAP5 - UMR 8145 - Mathématiques Appliquées Paris 5
5 Service Epidémiologie clinique et santé publique [CHU Toulouse]
6 IRCCS Istituto Nazionale dei Tumori [Milano]
7 University of Naples Federico II = Università degli studi di Napoli Federico II
8 A.O.U - Città della Salute e della Scienza di Torino
9 Ragusa Cancer Registry
10 Imperial College London
11 IIGM - Italian Institute for Genomic Medicine
12 UniFI - Università degli Studi di Firenze = University of Florence = Université de Florence

Background: Women with an advantaged socioeconomic position (SEP) have a higher risk of developing breast cancer (BC). The reasons for this association do not seem to be limited to reproductive factors and remain to be understood. We aimed to investigate the impact of lifecourse SEP from childhood and social mobility on the risk of BC considering a broad set of potential mediators. Methods: We used a discovery-replication strategy in two European prospective cohorts, E3N (N = 83,436) and EPIC-Italy (N = 20,530). In E3N, 7877 women were diagnosed with BC during a median 24.4 years of follow-up, while in EPIC-Italy, 893 BC cases were diagnosed within 15.1 years. Hazard ratios (HR) were estimated using Cox proportional hazard models on imputed data. Results: In E3N, women with higher education had a higher risk of BC (HR [95%CI] = 1.21 [1.12, 1.30]). This association was attenuated by adjusting for reproductive factors, in particular age at first childbirth (HR[95%CI] = 1.13 [1.04, 1.22]). Health behaviours, anthropometric variables, and BC screening had a weaker effect on the association. Women who remained in a stable advantaged SEP had a higher risk of BC (HR [95%CI] = 1.24 [1.07; 1.43]) attenuated after adjustment for potential mediators (HR [95%CI] = 1.13 [0.98; 1.31]). These results were replicated in EPIC-Italy. Conclusions: These results confirm the important role of reproductive factors in the social gradient in BC risk, which does not appear to be fully explained by the large set of potential mediators, including cancer screening, suggesting that further research is needed to identify additional mechanisms.

Mots clés: Breast cancer; Lifecourse socio-economic position; Prospective cohorts; Social mobility

Domaines: Cancer

Eloïse Berger, Noële Maitre, Francesca Romana Mancini, Laura Baglietto, Vittorio Perduca, et al.. The impact of lifecourse socio-economic position and individual social mobility on breast cancer risk. BMC Cancer, 2020, 20 (1), ⟨10.1186/s12885-020-07648-w⟩. ⟨hal-03109196⟩