This study aimed to compare the activity of Thymidine Kinase 1 in serum of two groups of woman at high and normal risk for breast/ovary cancer.

Hereditary breast/ovarian cancer syndrome is associated with mutations in tumor suppressor BRCA1 and BRCA2 genes. Products of these genes play an important role in the repair of DNA double-strand breaks. Mutations in BRCA1 and BRCA2 genes could impair DNA repair. In resting or G1 cells, where the de novo synthesis of DNA precursors is absent, the salvage pathway is the sole provider of deoxyribonucleotides to be used in DNA repair. For this process a sufficient supply of deoxynucleotides and activity of Thymidine Kinase 1 are essential. TK1 is an important component of adaptive response of cells to DNA damage. Mutations in genes directly engaged in the DNA repair process could lead to the accumulation of DNA damage and in turn cause an adaptive cell reaction manifesting as permanently increased Thymidine Kinase 1 activity.

A recently developed new high-sensitive assay DiviTum® allows to investigate the contribution of this enzyme to DNA repair processes and to make a comparison of Thymidine kinase 1 activity in women with normal and impared DNA repair system.

Inclusion Criteria:

• women from family with more than two breast cancer cases and one or more cases of ovarian cancer diagnosed at any age;
• women from family with more than three breast cancer cases diagnosed before the age 50;
• women from family withsister pair in which one of the following combinations was diagnosed before the age of 50: two breast cancers, two ovarian cancers, or a breast and ovarian cancer.

Exclusion Criteria:•

• pregnant women;
• women with generalized CMV and HZV infections;
• women with severe B12 deficiency and megaloblastic anaemia;
• women with severe rheumatoid arthritis.

women visiting the outpatient oncology clinic for genetic/familial high-risk assessments