Breast cancer risks in individuals testing negative for a known  family mutation in BRCA1 or BRCA2.
Genetic testing for BRCA1 and BRCA2 mutations in family members of individuals with known deleterious mutations can distinguish between patients at high risk of disease and those who are not. Some studies have suggested that individuals testing negative for known familial mutations (true negatives), may still have a higher risk of breast cancer (BC) than the general population. We have examined a prospectively followed cohort of true negative women in the US. Subjects were close relatives of known BRCA1 and BRCA2 mutation carriers who had undergone genetic testing, were negative for the known familial mutation, and were unaffected at the time of genetic testing. Standardized incidence ratios (SIR) and 95% confidence intervals (CI) were calculated using SEER incidence rates. Among 375 true negatives, two invasive and two in situ BC and no ovarian cancers were diagnosed with mean follow up of 4.9 years (total of 1,962 person years).Four invasive BC were expected, whereas two were observed, for an age-adjusted SIR of 0.52 (95% CI 0.13-2.09). We observed more cases of in situ BC (n = 2) than were expected (n = 0.9; SIR = 2.30; 95% CI 0.57-9.19).There were no cases of ovarian cancer observed; 0.4 case was expected. In this prospective study of women who were unaffected at the time of genetic testing and who were negative for the known familial mutation in BRCA1/2, no excess risk of invasive BC was observed. Our data suggest that such women in the US should adhere to population based guidelines for breast cancer screening.
Domchek
S M
SM
Abramson Cancer Center, University of Pennsylvania, 3 West Perelman Center, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA. susan.domchek@uphs.upenn.edu
Gaudet
M M
MM
Stopfer
J E
JE
Fleischaut
M H
MH
Powers
J
J
Kauff
N
N
Offit
K
K
Nathanson
K L
KL
Robson
M
M
D000328:Adult; D051017:Apoptosis Regulatory Proteins; D019313:BRCA1 Protein / Q000235:genetics*; D024682:BRCA2 Protein / Q000235:genetics*; D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D019983:Guideline Adherence; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009154:Mutation; D009361:Neoplasm Invasiveness; D010375:Pedigree; D010641:Phenotype; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D051017:Apoptosis Regulatory Proteins; C118024:BLID protein, human; D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D024682:BRCA2 Protein; C551750:BRCA2 protein, human; D014408:Biomarkers, Tumor