191P - Prognostic and predictive impact of Ki-67 index in neo-adjuvant chemotherapy before surgery in non-small cell lung cancer

Date 30 September 2012
Event ESMO Congress 2012
Session Poster presentation II
Topics Biomarkers
Lung and other Thoracic Tumours
Presenter Jan Nyrop Jakobsen
Authors J.N. Jakobsen1, E. Santoni-Rugiu2, J.B. Sorensen1
  • 1Oncology, National University Hospital, 2100 - Copenhagen/DK
  • 2Pathology, National University Hospital, 2100 - Copenhagen/DK

Abstract

Background

Immunohistochemical assessment of the proportion of Ki-67-expressing cells is a method for evaluating proliferation rates in malignant tumors. Ki-67 index is therefore a proliferation marker and may potentially be used as a prognostic or predictive marker during chemotherapy. In this study we correlated Ki-67 index to prognosis and chemo-sensitivity in non-small cell lung cancer (NSCLC) patients treated with neoadjuvant chemotherapy before surgery.

Materials and methods

Immunohistochemical assessment of Ki-67 index was performed on diagnostic biopsies from patients with histologically verified NSCLC stages T1-3N2M0 treated with neo-adjuvant chemotherapy (paclitaxel 225 mg/m2 and carboplatin AUC 6) followed by attempt of tumor resection and radiotherapy (2 Gy x 30Fr/ 5F/W). Ki-67 index was defined as the percentage of stained tumor cells in biopsies containing at least 100 tumor cells.

Results

A total of 64 biopsies (26 biopsies from primary tumors and 38 from lymph node metastases) from 51 consecutive patients were suitable for analysis. No significant differences in Ki-67 index between primary tumor (median ki-67 index 40%) and lymph nodes (median Ki-67 index 50%) were observed (p = 0.871). The 5-year-survival was 30% (Ki-67 index<40%) and 10% (Ki-67 index ≥ 40%) (p = 0.137), respectively. The 5-year-survival when the specimens were grouped according to Ki-67 index assessed in hot spots (focal areas with increased ratio of Ki-67-stained cells; median = 50%) was 40% (Ki-67 index<50%) and 4% (Ki-67 index ≥ 50%), respectively (p = 0.001). No significant correlations between Ki-67 index and response to chemotherapy or to surgical-pathological response were observed.

Conclusion

When assessed in hotspots, Ki-67 index is a prognostic marker for overall-survival and progression-free survival in NSCLC treated with neoadjuvant paclitaxel and carboplatin before surgery, which may reflect detection of areas with more malignant tumor clones with higher proliferation rate. However, Ki-67 index is not predictive marker for paclitaxel and carboplatin efficacy.

Disclosure

All authors have declared no conflicts of interest.