Pre-treatment proliferation and the outcome of conventional and accelerated radiotherapy.
Wilson GD., Saunders MI., Dische S., Daley FM., Buffa FM., Richman PI., Bentzen SM.
This study investigated the influence of pre-treatment proliferation characteristics, assessed by Ki-67 staining, in patients treated in the CHART trial of accelerated radiotherapy in head and neck cancer. Histological material from 402 patients was collected and stained for the presence and pattern of Ki-67 staining. Locoregional control and overall survival were the main clinical endpoints. Increasing Ki-67 positivity was associated with decreasing differentiation (P < 0.001) and increasing N-stage (P < 0.004). Increasing N-stage was also associated with the progression of proliferation pattern from marginal to random (P < 0.001). Using a multivariate model, a trend was seen towards a greater benefit from CHART in the lower Ki-67 tumours (P = 0.08); this became significant by pooling the low and intermediate Ki-67 groups in comparison with the high Ki-67 group (P = 0.032). Tumours with marginal proliferation pattern showed a lower hazard ratio with CHART versus conventional for locoregional control (P = 0.005). The data presented in this study do not support that a high pre-treatment Ki-67 is associated with a therapeutic benefit from accelerated radiotherapy.