Detecting tumor-related alterations in plasma or serum DNA of patients diagnosed with breast cancer

Chromosomal abnormalities are associated with the development of breast can cer, and widespread allelic loss or imbalance is frequently found in tumor tissues taken from patients with this disease. Using different markers, we studied a total of 61 patients (divided into three groups) for the presence of microsatellite instability and loss of heterozygosity (LOH) in plasma o r serum DNA, Of the initial 27 patients, 35% of the tumor samples displayed LOH, whereas 15% had identical alterations in the corresponding plasma sam ples, In addition, the adjacent normal breast tissue of two patients also d isplayed LOH, In a second group of 11 patients, 45% of the tumors displayed LOH, and 27% displayed identical plasma DNA alterations; one case displaye d an identical LOH in adjacent nontumor tissue. In a third series of 23 pat ients also studied with tetranucleotide repeats, 81% of the tumor samples d isplayed LOH, whereas 48% had LOH in the corresponding serum samples. The f act that small tumors (T-1) of histoprognostic grade 1 or in situ carcinoma s could present DNA alterations in the plasma/serum at an early stage, alli ed to the widely increased range of available microsatellite markers, sugge sts that plasma of serum DNA may become a useful diagnostic tool for early and potentially curable breast cancer.