Clinical cancer genetics is an emerging new field in medical oncology, and has been incorporated into routine oncology practice in many leading medical institutions in North America and Europe. Cancer genetics is the study of genetic factors contributing to carcinogenesis. In the last 5-10 years, genes responsible for various well-defined hereditary cancer syndromes have been cloned. These include the BRCAJ/2 genes in hereditary breast and ovarian cancer syndrome, the A4PC gene in Familial Adenomatous Polyposis, and the mismatch repair genes (hMLH1, hMSH2, hPMS1, hPMS2, hMSH6) in hereditary non-polyposis colorectal cancer (HNPCC). One of the goals of a clinical cancer genetics service is to identify families at risk for hereditary cancer syndromes, provide genetic counseling, and offer genetic testing when appropriate. The identification of causative genes in hereditary cancer syndromes together with the advent of genetic testing is starting to have an impact on clinical management. The ability to identify a gene mutation in a cancer family allows predictive testing, stratifying at-risk family members into carriers who will benefit from aggressive surveillance and/or preventive options, and non-carriers who may be spared unnecessary surveillance. Appropriate use of genetic testing will ultimately result in medical cost reduction.
The investigators hypothesize that the clinical characteristics and genetic factors contributing to hereditary cancer in the Singaporean Asian population are distinct from those described for Western patients.