
There are multiple potential uses for cfDNA in cancer diagnosis and prognosis for example, cfDNA can be used to detect somatic alterations when biopsies are not available. It may also represent a valuable source of tumor DNA when the exact position of a suspected primary lesion is not clearly defined. Aside from these clinical applications, cfDNA may also represent a very important source of biomarkers in population-based studies. The fact that cfDNA can be obtained without invasive or painful procedures makes it particularly. We aimed to detected if there is any mutations in KRAS as genetic marker could be find in plasma samples from Iraqi patients as early diagnosis and compared the results with match tumor. Material and methods: Plasma samples for this study were collected in addition tumor tissue was collected via biopsy from 18 patients at early diagnosis of colorectal cancer. DNA was extracted from frozen tumor tissue and cfDNA was extracted from the plasma samples. KRAS mutations were detected by High Resolution Melting (HRM). Results: There is (33%) of patients tumour tissue with KRAS mutation in codon 12, KRAS mutation in sequencing analysis was successful only in (7%) of the plasma-extracted cfDNA sample which didn't mutate in the matched tumor. Conclusion: We found it is unlikely that circulating mutant DNA measurements be used to reliably monitor tumor diagnostic and monitoring potential of detecting of KRAS oncogene in plasma from Iraqi patients as early diagnosis based on the fact that we were unable to detect such DNA in plasma and match tumor tissue.