["Screening" in special situations. Assessing predictive genetic screening for hereditary breast and colorectal cancer].
OBJECTIVE
The aim of this health technology assessment was to analyse the current scientific and genetic counselling on predictive genetic testing for hereditary breast and colorectal cancer. Predictive genetic testing will be available for several common diseases in the future and questions related to financial issues and quality standards will be raised. This report is based on a systematic/nonsystematic literature search in several databases (e.g. EmBase, Medline, Cochrane Library) and on a specific health technology assessment report (CCOHTA) and review (American Gastroenterological Ass.), respectively. Laboratory test methods, early detection methods and the benefit from prophylactic interventions were analysed and social consequences interpreted.


BACKGROUND
Breast and colorectal cancer are counted among the most frequently cancer diseases. Most of them are based on random accumulation of risk factors, 5-10% show a familial determination. A hereditary modified gene is responsible for the increased cancer risk. In these families, high tumour frequency, young age at diagnosis and multiple primary tumours are remarkable.
GENETIC DIAGNOSIS: Sequence analysis is the gold standard. Denaturing high performance liquid chromatography is a quick alternative method. The identification of the responsible gene defect in an affected family member is important. If the test result is positive there is an uncertainty whether the disease will develop or not, when and in which degree, which is founded in the geno-/phenotype correlation. The individual risk estimation is based upon empirical evidence. The test results affect the whole family.
Currently, primary prevention is possible for familial adenomatous polyposis (celecoxib, prophylactic colectomy) and for hereditary mamma carcinoma (prophylactic mastectomy). The so-called preventive medical check-ups are early detection examinations. The evidence about early detection methods for colorectal cancer is better than for breast cancer.
Prophylactic mastectomy (PM) reduces the relative breast cancer risk by approximately 90%. The question is if PM has an impact on mortality. The acceptance of PM is culture-dependent. Colectomy can be used as a prophylactic (FAP) and therapeutic method. After surgery, the cancer risk remains high and so early detection examinations are still necessary. EVIDENCE-BASED STATEMENTS: The evidence is often fragmentary and of limited quality. For objective test result presentation information about sensitivity, specificity, positive predictive value, and number needed to screen and treat, respectively, are necessary.


CONCLUSIONS
New identification of mutations and demand will lead to an increase of predictive genetic counselling and testing. There is a gap between predictive genetic diagnosis and prediction, prevention, early detection and surgical interventions. These circumstances require a basic strategy. Since predictive genetic diagnosis is a very sensitive issue it is important to deal with it carefully in order to avoid inappropriate hopes. Thus, media, experts and politicians need to consider opportunities and limitations in their daily decision-making processes.
Jonas
Susanna
S
Institut für Technikfolgen-Abschätzung, Osterreichische Akademie der Wissenschaften, Wien. sjonas@oeaw.ac.at
Wild
Claudia
C
Schamberger
Chantal
C
D001943:Breast Neoplasms / Q000235:genetics* / Q000517:prevention & control*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000517:prevention & control*; D005260:Female; D005817:Genetic Counseling; D005820:Genetic Testing / Q000379:methods* / Q000592:standards*; D006801:Humans; D008403:Mass Screening / Q000379:methods; D011322:Primary Prevention