| Theme |
Molecular pathology of colorectal cancer for clinicians |
| Title |
Molecular Screening for Colorectal Cancer |
| Author |
Takashi Nishikawa |
Second Department of Internal Medicine, Osaka Medical College |
| Author |
Ichiro Hirata |
Second Department of Internal Medicine, Osaka Medical College |
| [ Summary ] |
Colorectal cancer is one of the most common cancers in Japan. The identification of high-risk individuals and the early diagnosis of colorectal cancer are crucial since a large proportion can be prevented or usually be cured either by colonoscopic resection or by surgery. Recent discoveries in genetic and molecular biology have revolutionized our understanding of colorectal carcinogenesis and the development of molecular techniques has made it feasible to analyze samples that contain a low proportion of tumor cells, such as stool samples. Colorectal cancer can be diagnosed by molecular characterizations, such as activation of oncogenes, inactivation of tumor suppressor genes, or alteration of DNA repair genes. Several studies showed that it is possible to detect K-ras mutations in the DNA from colorectal cancer cells exfoliated in stool samples. Because K-ras point mutations are only associated with 40-50% of colorectal cancers, the detection sensitivity is low among cancers as a whole. However, the technique should provide a more sensitive and specific tool for colorectal cancer screening, if used in combination with detection of other genetic alterations. Molecular screening will hopefully be developed and should result in a reduction of morbidity and mortality from colorectal cancer. |