Is the thymidine labeling index a good prognostic marker in breast cancer?

BACKGROUND The aim of the present study was to determine the prognostic relevance of thymidine labeling index (TLI) in patients with breast cancer. METHODS TLI of the primary tumor was measured in 268 patients at the time of the surgical biopsy by an in vitro method. RESULTS Fifty-four patients had stage I disease, and 138 patients had stage II disease, and 76 patients had stage III disease. One hundred-four patients were found to have low TLI-index (<3%), and 164 patients had high TLI-index (>/=3%). The median follow-up was 71.5 months (range, 6-138 months). The 5-year overall survival (OS) and disease free survival (DFS) rates was 84% and 74%, respectively. Lymph node involvement, tumor size more than 2 cm, high nuclear grade and estrogen receptor negativity were found to be associated with poorer DFS and OS rates. On subgroup analysis, however, the 5-year OS rate was significantly higher in the low TLI-group than in the high TLI-group in patients with stage I disease (100% vs 76%, p = 0.05). CONCLUSION Our findings suggest that the prognostic significance of TLI appears to be limited to early breast cancer that might help to distinguish patients who need more aggressive adjuvant treatment.