Analysis of polymorphs:SNP in the ERß-gene will be analysed in blood samples, using the PCR-based method competitive allele specific PCR (KASP™). The allele-constitution will be identified and participants will be assigned to group TT, TC or CC. Analysis of Ki-67: The biopsy sample is fixed by immersion with 4 % paraformaldehyde in 0,1 M phosphate buffer during 24hours at +4°C. Then it is dehydrated with graded ethanol followed by xylene and paraffin embedding. Paraffin sections are heated for 30 minutes at 60ºC, pre-treated with citric acid buffer. Unspecific binding is blocked by donkey serum in phosphate buffered saline (PBS) containing Triton X-100 for 30 minutes. Incubating with Ki-67 antibody over night (4ºC) followed by incubation with the appropriate secondary biotinylated antibody. To enhance the signal, the sections are treated with avidin-biotin-complex solution, and to visualize the immunoreactivity Diaminobenzidine (DAB) is used. Stained tumor cells (Ki-67 positivity) will be counted and the result will be reported as the ratio of positive nuclei divided by the total number evaluated × 100.