Biological considerations in locally advanced breast cancer treated with anthracycline-based neoadjuvant chemotherapy: thymidine labelling index is an independent indicator of clinical outcome

The present retrospective study aims to determine the clinical value of thy midine labelling index (TLI) together with other established clinical and b iological factors in 116 locally advanced breast cancer (LABC) patients tre ated with anthracycline-based neoadjuvant chemotherapy, surgery, adjuvant c hemotherapy and radiotherapy. TLI was determined in 71 LABC patients with a median of 2.62% (0-23.64%) and a mean of 4.71% +/- 5.54. As a result of ne oadjuvant chemotherapy, 85 patients (73%) responded to chemotherapy (CT), w hereas 31 patients were unresponsive (27%). No relationship has been found between the pretreatment biological variables including TLI, estrogen recep tor (ER), progesteron receptor (PgR) status and clinical parameters such as the chemotherapy response rates and axillary lymph node involvement follow ing chemotherapy. Median follow-up was 35 months (18-97 months) and the 3-y ear overall survival (OS) and disease free survival (DFS) rates were 71.6% and 52.2%, respectively. In univariate analysis, patients with inflammatory breast cancer, high TLI-index (greater than or equal to2.62%), lymph node (LN) positivity or >3 positive lymph nodes following neoadjuvant chemothera py and without any response to neoadjuvant chemotherapy were found to have worse DFS and OS-rates and high local and systemic recurrence rates. In mul tivariate analysis, TLI was estimated as the most powerful independent fact or affecting the OS in LABC patients among the other established clinical a nd biological parameters (p = 0.02). These results suggest that TLI is an i mportant independent indicator of clinical outcome in patients with LABC an d these patients with high TLI levels require more effective treatment moda lities.