Presence of tumor DNA in plasma of breast cancer patients: Clinicopathological correlations

Using different molecular techniques, DNA has been detected in the plasma o f cancer patients with various types of tumors. We undertook the present st udy to investigate the presence of plasma DNA, before mastectomy, in patien ts with breast cancer at diagnosis and to analyze the clinicopathological s pectrum of this subgroup of patients with respect to patients without DNA w ith tumor characteristics. We studied 62 patients with breast cancer, who w ere selected sequentially after mastectomy and diagnosis of breast carcinom as. Genomic DNA extracted from tumor and normal tissues, normal blood cells , and plasma was used for molecular studies. Alterations in polymorphic mar kers selected because they had been found to show a high rate of alteration s in breast cancer in previous studies (D17S855, D17S654, D16S421, TH2, D10 S197, and D9S161), as well as mutations in the p53 gene and aberrant methyl ation at the first exon of p16(INK4a), were used to identify and characteri ze tumor and plasma DNA. Thirteen clinicopathological parameters were analy zed in each patient. We identified 56 cases (90%) with at least one molecul ar event in tumor DNA, and 41 cases (66%) with a similar alteration in plas ma DNA, Comparison of the clinicopathological parameters between patients w ith and without plasma DNA revealed significant differences in the axillary involvement, rate of invasive ductal carcinoma, high proliferative index, and the parameter comprised of lymph node metastases, histological grade II I, and peritumoral vessel involvement. A high proportion of breast cancer p atients exhibited plasma DNA at diagnosis similar to tumor DNA, and its pre sence correlated significantly with pathological parameters associated with a poor prognosis.