Telomerase expression and telomere length in breast cancer and their associations with adjuvant treatment and disease outcome

qPCR and qRT-PCR were used to analyze telomere length and telomerase expression, respectively, in tumor samples of 348 breast cancer patients. Cox regression analysis was performed to examine telomere length and telomerase expression in association with disease-free survival and cause-specific mortality.Telomere length had no relation to tumor features or disease outcomes. Telomerase expression was detected in 53% of tumors. Larger tumors or aggressive disease were more likely to have telomerase expression. Among patients treated with chemotherapy, high telomerase was found to be associated with increased risk of death (hazard ratio (HR) = 3.15; 95% CI: 1.34 to 7.40) and disease recurrence (HR = 2.04; 95% CI: 0.96 to 4.30) regardless of patient age, disease stage, tumor grade, histological type or hormone receptor status. Patients treated with endocrine therapy had different results regarding telomerase: high telomerase appeared to be associated with better survival outcomes. Telomerase expression made no survival difference in patients who received both chemotherapy and endocrine therapy.Overall, telomerase expression was not associated with disease outcome, but this finding may be masked by adjuvant treatment. Patients with high telomerase expression responded poorly to chemotherapy in terms of disease-free and overall survival, but fared better if treated with endocrine therapy.Telomeres are repeated sequences of oligonucleotides (TTAGGG) located at the ends of chromosomes, and have important functions in regulating cell replication and maintaining genome integrity [1-3]. The length of telomeres decreases with the number of cell divisions; reduced telomere length carries functional cellular signals. Cells enter senescence or initiate apoptosis when telomere length is reduced to a critical level. Shortened telomere length often leads to genome instability, resulting in loss of cell-cycle control, a hallmark of cancer. Telomere shortening has been found to be assoc