An evaluation of common breast cancer gene mutations in a population of Ashkenazi Jews

A new scoring system for the chances of identifying a BRCA1/2 mutation outperforms existing models including BRCAPRO

PURPOSE

To develop a simple scoring system for the likelihood of identifying a BRCA1 or BRCA2 mutation.

METHODS

DNA samples from affected subjects from 422 non-Jewish families with a history of breast and/or ovarian cancer were screened for BRCA1 mutations and a subset of 318 was screened for BRCA2 by whole gene screening techniques. Using a combination of results from screening and the family history of mutation negative and positive kindreds, a simple scoring system (Manchester scoring system) was devised to predict pathogenic mutations and particularly to discriminate at the 10% likelihood level. A second separate dataset of 192 samples was subsequently used to test the model's predictive value. This was further validated on a third set of 258 samples and compared against existing models.

RESULTS

The scoring system includes a cut-off at 10 points for each gene. This equates to >10% probability of a pathogenic mutation in BRCA1 and BRCA2 individually. The Manchester scoring system had the best trade-off between sensitivity and specificity at 10% prediction for the presence of mutations as shown by its highest C-statistic and was far superior to BRCAPRO.

CONCLUSION

The scoring system is useful in identifying mutations particularly in BRCA2. The algorithm may need modifying to include pathological data when calculating whether to screen for BRCA1 mutations. It is considerably less time-consuming for clinicians than using computer models and if implemented routinely in clinical practice will aid in selecting families most suitable for DNA sampling for diagnostic testing.

Risk assessment and management of high risk familial breast cancer

The demand for genetic services by women with a family history of breast cancer has increased exponentially over the last few years. It is important that risks to women are accurately assessed and that processes are in place for appropriate counselling and management. The classification of risk into average, moderate, and high, depending upon the assessed lifetime risk of breast cancer, allows for the management of moderate risk women within cancer units and high risk women within the regional genetic centres. Management of high risk women includes discussion of options including screening, chemoprevention, and preventive surgery. The majority of these options are still unproven in the long term and continuing research is needed for their evaluation. Mutation screening and predictive testing are now a reality for a minority of families, allowing for a more informed basis for decisions regarding management options.

p53 and WAF1 polymorphisms in Jewish-Israeli women with epithelial ovarian cancer and its association with BRCA mutations

OBJECTIVE

To investigate whether polymorphic p53 and WAF1 alleles are associated with clinical, demographic and histopathological features and BRCA mutation in women with ovarian cancer.

DESIGN

A cross-sectional study.

POPULATION

Two hundred and twenty-one nonselected Israeli women with epithelial ovarian cancer.

METHODS

DNA was analysed for known polymorphisms in intron 3 (a 16 nucleotide single repeat) and intron 6 (a G to A change at nucleotide 13,494) of the p53 gene, the S31R polymorphism in the WAF1 gene, and for three predominant Jewish mutations in the BRCA genes (185delAG and 5382insC in BRCA1, and 6174delT in BRCA2).

MAIN OUTCOME MEASURE

The rate of polymorphic p53 and WAF1 alleles and their association with BRCA mutation, ethnic origin, age and stage at diagnosis, and family history of cancer.

RESULTS

Of the tested women, 72 (32.6%) were either BRCA1 (n = 57) or BRCA2 (n = 15) mutation carriers. Sixty-eight of 213 (31.9%) were heterozygous for intron 3 polymorphism, 67/193 (34.7%) for intron 6 polymorphism, and 22/154 (14.3%) for S31R of the WAF1 gene. The p53 and WAF1 polymorphism rate did not differ between BRCA mutation carriers and noncarriers. No significant association between specific p53 or WAF1 genotypes, and clinical, histopathological or demographic variables was observed.

CONCLUSION

In Jewish-Israeli women with sporadic and familial ovarian cancer, p53 or WAF1 polymorphisms do not seem to affect the phenotype.

Guidelines for a genetic risk based approach to advising women with a family history of breast cancer. UK Cancer Family Study Group (UKCFSG)

A family history of breast cancer has long been recognised as a significant risk factor for breast cancer. Quantifying that risk has been approached in publications and practically in a number of different ways. Increasingly regional genetics departments are called upon to help clarify guidelines for referral of women with a family history of breast cancer for genetic testing and to clarify breast cancer risk for women seeking early mammographic screening. This paper represents the current consensus guidelines from the UK Cancer Family Study Group and discusses some of the difficulties surrounding genetic risk estimation.

Risk factors for detecting germline BRCA1 and BRCA2 founder mutations in Ashkenazi Jewish women with breast or ovarian cancer

We ascertained 184 Ashkenazi Jewish women with breast/ovarian cancer (171 breast and 13 ovarian cancers, two of the former also had ovarian cancer) in a self-referral study. They were tested for germline founder mutations in BRCA1 (185delAG, 5382insC, 188del11) and BRCA2 (6174delT). Personal/family histories were correlated with mutation status. Logistic regression was used to develop a model to predict those breast cancer cases likely to be germline BRCA1/BRCA2 mutation carriers in this population. The most important factors were age at diagnosis, personal/family history of ovarian cancer, or breast cancer diagnosed before 60 years in a first degree relative. A total of 15.8% of breast cancer cases, one of 13 ovarian cancer cases (7.7%), and both cases with ovarian and breast cancer carried one of the founder mutations. Age at diagnosis in carriers (44.6 years) was significantly lower than in non-carriers (52.1 years) (p<0.001), and was slightly lower in BRCA1 than BRCA2 carriers. Thirty three percent of carriers had no family history of breast or ovarian cancer in first or second degree relatives. Conversely, 12% of non-mutation carriers had strong family histories, with both a first and a second degree relative diagnosed with breast or ovarian cancer. The predicted values from the logistic model can be used to define criteria for identifying Ashkenazi Jewish women with breast cancer who are at high risk of carrying BRCA1 and BRCA2 mutations. The following criteria would identify those at approximately 10% risk: (1) breast cancer <50 years, (2) breast cancer <60 years with a first degree relative with breast cancer <60 years, or (3) breast cancer <70 years and a first or second degree relative with ovarian cancer.