Survival benefit in women with BRCA1 mutation or familial risk in the MRI screening study (MRISC)
Menée aux Pays-Bas auprès de 2 308 femmes présentant un risque héréditaire de cancer du sein ou une mutation du gène BRCA1 ou BRCA2 et incluses dans un programme de dépistage, cette étude évalue l'intérêt d'ajouter une IRM à une mammographie annuelle pour améliorer la survie sans métastase ou la survie globale des patientes pour lesquelles un cancer du sein a été détecté (93 cas ; durée médiane de suivi : 9 ans)
Adding MRI to annual mammography screening improves early breast cancer detection in women with familial risk or BRCA1/2 mutation, but breast cancer specific metastasis free survival (MFS) remains unknown. We compared MFS of patients from the largest prospective MRI Screening Study (MRISC) with 1:1 matched controls. Controls, unscreened if<50 years, and screened with biennial mammography if ≥50 years, were matched on risk category (BRCA1, BRCA2, familial risk), year and age of diagnosis. Of 2,308 MRISC participants, breast cancer was detected in 93 (97 breast cancers), who received MRI <2 years before breast cancer diagnosis; 33 BRCA1 mutation carriers, 18 BRCA2 mutation carriers, and 42 with familial risk. MRISC patients had smaller (87% vs. 52% <T2, p < 0.001), more often node negative (69% vs. 44%, p = 0.001) tumors and received less chemotherapy (39% vs. 77%, p < 0.001) and hormonal therapy (14% vs. 47%, p < 0.001) than controls. Median follow-up time was 9 years (range 0–14). Breast cancer metastasized in 9% (8/93) of MRISC patients and in 23% (21/93) of controls (p = 0.009). MFS was better in MRISC patients overall (log-rank p = 0.008, HR 0.36, 95% CI 0.16–0.80), with familial risk (log-rank p = 0.024, HR: 0.21, 95% CI 0.04–0.95), and in BRCA1 mutation carriers (log-rank p = 0.055, HR 0.30, 95% CI 0.08–1.13). MFS remained better in MRISC patients after lead time correction (log-rank p = 0.020, HR 0.40, 95% CI 0.18–0.90). Overall survival was non-significantly better in MRISC patients (log-rank p = 0.064, HR 0.51, CI 0.24–1.06). Annual screening with MRI and mammography improves metastasis free survival in women with BRCA1 mutation or familial predisposition.
International Journal of Cancer , résumé, 2014