[Clinical and molecular diagnosis of inherited breast-ovarian cancer].
OBJECTIVE
The aim of this work was to pinpoint familial breast and/or ovarian cancer risk. Clinical cancer genetics include: diagnostic cancer genetics, cancer genetic counseling and management of women at high risk of developing breast and/or ovarian cancer.


METHODS
An update of documented data was performed in order to assess our current knowledge about inherited breast-ovarian cancer.


RESULTS
Most breast cancers (BC) are sporadic while 5-10% are estimated to be due to an inherited predisposition. Rare autosomal dominant alteration in two genes, BRCA1 and BRCA2, which confer a high risk of developing BC and ovarian cancer (OC), are likely to account for most families with multiple cases of early-onset BC and OC, but only 3-4% of all BC. The estimations of their prevalence and penetrance vary greatly, depending on the population studied, the study design, statistical methods and the sensitivity of technical methods for detection of mutations. Penetrance can be very high, but incomplete (maximum 80%). Penetrance and age at onset of the same mutation show great variability within and between BC families. This could be due to the effects of other genetic as well as non-genetic factors that are being studied. The heterogeneity of families makes the identification of other high-risk genes difficult. Additive effects of several susceptibility genes could explain much more BC in the general population (polygenic models). Molecular diagnoses have become feasible. Specific consultations in oncogenetics help clinicians and patients understand hereditary components, establish molecular diagnoses, provide guidelines for a better surveillance of people at high risk of developing BC, OC or both and reassure the mutation non-carriers. The strategies of management and treatment of BC and OC in mutation carriers remain under discussion and it is is difficult to choose preventive options.


CONCLUSIONS
Inherited BC or OC due to a mutation in BRCA1 or BRCA2 are rare in the general population. However, women and men have the right to be informed of the possibilities concerning presymptomatic testing, risk assessment, surveillance, prevention and psychological support with respect to the potential benefits and limitations. Other large prospective studies are needed to validate rapidly the methods of surveillance and prevention in this group at "high risk" in order to adapt them to very large populations. However, predictive medicine should be used with care.
Chompret
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Consultation d'Oncogénétique, Institut Gustave-Roussy, 39, rue Camille-Desmoulins, 94805 Villejuif Cedex. chompret@igr.fr
D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics* / Q000517:prevention & control; D005260:Female; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006801:Humans; D009154:Mutation; D010051:Ovarian Neoplasms / Q000175:diagnosis* / Q000235:genetics* / Q000517:prevention & control; D011159:Population Surveillance; D012307:Risk Factors
Diagnostic génétique du cancer du sein et de l'ovaire héréditaire.