Association of type and location of BRCA1 and BRCA2 mutations with risk of breast and ovarian cancer

Rebbeck, Timothy R., Mitra, Nandita and Wan, Fei et al. , CIMBA Consortium (2015) Association of type and location of BRCA1 and BRCA2 mutations with risk of breast and ovarian cancer. JAMA, 313 (13), 1347-1361. (doi:10.1001/jama.2014.5985). (PMID:25849179)

Abstract

IMPORTANCE:
Limited information about the relationship between specific mutations in BRCA1 or BRCA2 (BRCA1/2) and cancer risk exists.

OBJECTIVE:
To identify mutation-specific cancer risks for carriers of BRCA1/2.

DESIGN, SETTING, AND PARTICIPANTS:
Observational study of women who were ascertained between 1937 and 2011 (median, 1999) and found to carry disease-associated BRCA1 or BRCA2 mutations. The international sample comprised 19,581 carriers of BRCA1 mutations and 11,900 carriers of BRCA2 mutations from 55 centers in 33 countries on 6 continents. We estimated hazard ratios for breast and ovarian cancer based on mutation type, function, and nucleotide position. We also estimated RHR, the ratio of breast vs ovarian cancer hazard ratios. A value of RHR greater than 1 indicated elevated breast cancer risk; a value of RHR less than 1 indicated elevated ovarian cancer risk.

EXPOSURES:
Mutations of BRCA1 or BRCA2.

MAIN OUTCOMES AND MEASURES:
Breast and ovarian cancer risks.

RESULTS:
Among BRCA1 mutation carriers, 9052 women (46%) were diagnosed with breast cancer, 2317 (12%) with ovarian cancer, 1041 (5%) with breast and ovarian cancer, and 7171 (37%) without cancer. Among BRCA2 mutation carriers, 6180 women (52%) were diagnosed with breast cancer, 682 (6%) with ovarian cancer, 272 (2%) with breast and ovarian cancer, and 4766 (40%) without cancer. In BRCA1, we identified 3 breast cancer cluster regions (BCCRs) located at c.179 to c.505 (BCCR1; RHR?=?1.46; 95% CI, 1.22-1.74; P?=?2?×?10(-6)), c.4328 to c.4945 (BCCR2; RHR?=?1.34; 95% CI, 1.01-1.78; P?=?.04), and c. 5261 to c.5563 (BCCR2', RHR?=?1.38; 95% CI, 1.22-1.55; P?=?6?×?10(-9)). We also identified an ovarian cancer cluster region (OCCR) from c.1380 to c.4062 (approximately exon 11) with RHR?=?0.62 (95% CI, 0.56-0.70; P?=?9?×?10(-17)). In BRCA2, we observed multiple BCCRs spanning c.1 to c.596 (BCCR1; RHR?=?1.71; 95% CI, 1.06-2.78; P?=?.03), c.772 to c.1806 (BCCR1'; RHR?=?1.63; 95% CI, 1.10-2.40; P?=?.01), and c.7394 to c.8904 (BCCR2; RHR?=?2.31; 95% CI, 1.69-3.16; P?=?.00002). We also identified 3 OCCRs: the first (OCCR1) spanned c.3249 to c.5681 that was adjacent to c.5946delT (6174delT; RHR?=?0.51; 95% CI, 0.44-0.60; P?=?6?×?10(-17)). The second OCCR spanned c.6645 to c.7471 (OCCR2; RHR?=?0.57; 95% CI, 0.41-0.80; P?=?.001). Mutations conferring nonsense-mediated decay were associated with differential breast or ovarian cancer risks and an earlier age of breast cancer diagnosis for both BRCA1 and BRCA2 mutation carriers.

CONCLUSIONS AND RELEVANCE:
Breast and ovarian cancer risks varied by type and location of BRCA1/2 mutations. With appropriate validation, these data may have implications for risk assessment and cancer prevention decision making for carriers of BRCA1 and BRCA2 mutations.

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Contributors

Author: Diana Eccles

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