LB43
Growth fraction assessment using Ki-67/Mib1 labelling index: a predictor of response to adjuvant therapy in breast cancer patients
Mohammed Aleskandarany1, Andrew Green1, Emad Rakha2, Rabab Ahmed1, Somaia Elsheikh1, Claire Paish2, Ian Ellis1
1University of Nottingham, UK, 2Nottingham University Hospitals NHS Trust, UK
Background
The wide spread use of mammographic screening and the frequent application
of breast conserving surgery has resulted in the increased use of adjuvant
systemic therapy. However, the level of response and the potentially serious
side-effects of these systemic anticancer therapies in addition to the
cost-effect relationship have increased our need to identify relevant
predictive markers that can be used in planning treatment decision in routine
practice.
Method
The usefulness of tumour growth fraction (GF) assay in predicting response
to adjuvant hormone (tamoxifen) and (CMF) chemotherapy was assessed, using the
Ki-67 specific antibody MIB1, in a well characterised series of primary
operable breast carcinoma cases (n=612) with long-term follow-up (median 10
years).
Results
Our results showed that patients with ER+ high GF tumours were
associated with poor outcome when treated with adjuvant tamoxifen therapy
alone, in terms of shorter breast cancer specific survival (BCSS; Hazard ratio
(HR)=1.583, 95% CI=1.2232.049, p< 0.001) and disease free interval
(DFI; HR=1.438, 95% CI=1.126-1.836, p=0.004). This effect was
independent of patients age, tumour grade, size and nodal status. However,
those with high GF tumours showed significantly longer BCSS and DFI when
treated with adjuvant CMF chemotherapy. This effect was obvious in the lymph
node negative tumours (HR=0.403, 95% CI =0.2190.744, p=0.004 &
HR=0.479, 95% CI=0.266-1.864, p=0.014, for BCSS and DFI respectively)
but did not reach statistical significance in node positive cases.
Conclusion
Tumour GF could be used to assign patients into distinct groups showing
differential response to adjuvant therapy. Patients with high GF tumours appear
to be ideal candidates for adjuvant chemotherapy with or without hormone
therapy. Those with low growth fraction are less likely to benefit and are
prone to the potential serious side effects of adjuvant chemotherapy, for whom
adjuvant hormonal therapy should be considered.
