DETECTION OF TUMOR DNA IN SERUM OF COLORECTAL-CANCER PATIENTS

Circulating tumour DNA has previously been detected in serum and plasm a of patients with lung cancer and head and neck cancer. These observa tions could potentially lead to new, specific and non-invasive tools f or diagnosis, prognosis and follow-up in neoplastic disease, if found to be a more general phenomenon. To test if tumour DNA is also present in serum of patients with colorectal cancer, we selected 14 colorecta l cancer patients with advanced disease. In seven patients, K-ras muta tions were detected in the primary tumour, using mutant-specific prime rs for point mutations in codon 12 or 13 of the K-ras gene. All patien ts were analysed for mutant DNA in serum. Tumour-specific point mutati ons, corresponding to the K-ras mutations found in the primary tumour were detected in the serum of all patients but one. No mutant K-ras co uld be detected in the serum of seven patients without K-ras mutations in the primary tumour. These results may be useful in assessing tumou r burden in patients with neoplastic disease. Moreover, consecutive te sting of serum tumour DNA after surgery or chemotherapy may be used as a tumour marker for recurrent disease.