In vitro radiosensitivity of tumour cells and fibroblasts derived from head and neck carcinomas: mutual relationship and correlation with clinical data

The aim was to characterize the variation in the cellular in vitro radiosensitivities in squamous cell carcinomas of the head and neck, and to test for a possible correlation between different measures of radiosensitivity and the clinical and histopathological data. Cellular in vitro radiosensitivities were assessed in tumour biopsies from 71 patients using the modified Courtenay–Mills soft agar clonogenic assay combined with an immunocytochemical analysis. Radiosensitivity was quantified as the surviving fraction after a radiation dose of 2 Gy irrespective of cell type (overall SF2), or based on identification of cell type (tumour cell SF2, fibroblast SF2). Sixty-three biopsies were from primary tumours, and eight were from recurrences. Overall plating efficiency ranged from 0.005 to 1.60% with a median of 0.052%. The majority of the colonies obtained from the biopsies were fibroblast marker-positive; the proportion of tumour marker-positive colonies ranged from 1 to 88% with a median of 15%. The median overall SF2 was 0.47 (range 0.24–0.96), the median tumour cell SF2 was 0.50 (range 0.11–1.0) and the median fibroblast SF2 was 0.49 (range 0.24–1.0). Comparing data from independent experiments, the overall SF2 was significantly correlated with the SF2 of fibroblasts (2P = 0.006) but not with the tumour cell SF2. The tumour cell and fibroblast radiosensitivities measured in the same individuals were not correlated (r = 0.06, 95% CI [–0.19, 0.30]). This finding seems to preclude a strong correlation between the radiosensitivity of tumour cells and fibroblasts. Concerning the clinical characteristics, neither of the measures of tumour radiosensitivity was correlated with T- and N-category, stage, tumour size, sex and age. However, the tumour cell radiosensitivity decreased with increasing grade of histopathological differentiation (2P = 0.012). The same tendency was found in two independent analyses of the same patient material. This correlation was not significant in case of the overall SF2 or the fibroblast SF2. © 1999 Cancer Research Campaig

Failure-specific prognostic factors after continuous hyperfractionated accelerated radiotherapy (CHART) or conventional radiotherapy in locally advanced nonsmall-cell lung cancer: A competing risks analysis

The aim of this study was to identify possible failure-specific prognostic factors in non-small-cell lung cancer. Clinical outcome was analysed in 549 patients participating in the randomized controlled trial of CHART vs conventional radiotherapy. Local failure and distant failure with or without concurrent local relapse were subjected to a competing risk analysis using an accelerated failure-time model with a log-logistic hazard function. Randomization to CHART (2P = 0.005), increasing age (2P = 0.036) and female sex (2P = 0.09) was all associated with a prolonged interval to failure. Advanced clinical stage was associated with a decreased interval to failure (2P = 0.004) and a significantly increased risk (2P = 0.009) of failing in distant rather than in local position. From this model, prognostic indices for local and distant failure were estimated for each individual patient. Competing risk analysis allows identification of patients with different failure patterns, and may provide a means of stratifying patients for intensified local or systemic therapy. (C) 2001 Cancer Research Campaign

Molecular biomarkers and site of first recurrence after radiotherapy for head and neck cancer

The prognostic significance of a panel of molecular biomarkers in head and neck squamous cell carcinoma (HNSCC) for first failure site (primary (T), nodal (N) or distant (M)) was analysed in 309 patients randomised to continuous hyperfractionated accelerated radiotherapy (CHART) vs. conventionally fractionated radiotherapy. Multivariate competing risks analysis was performed using an accelerated failure-time model. First-order interactions between each marker and trial arm were also tested. Bcl2-positivity increased the time to T- and N-failures, increasing cyclin D I score decreased the time to N-failures. A random proliferative pattern and low Ki-67 decreased the time to M-failures. A high CD31 score was associated with a significantly longer time to T-failure after CHART, but not after conventional fractionation. Risks of T-, N- and M-failures could be estimated for individual patients. Competing risks analysis of failure sites allows the rational selection of patients for more aggressive loco-regional or systemic therapy. (C) 2004 Elsevier Ltd. All rights reserved

Molecular marker profiles predict locoregional control of head and neck squamous cell carcinoma in a randomized trial of continuous hyperfractionated accelerated radiotherapy.

PURPOSE: Identification of factors that assist prediction of tumor response to radiotherapy may aid in refining treatment strategies and improving outcome. Possible association of molecular marker expression profiles with locoregional control of head and neck squamous cell carcinoma was investigated in a randomized trial of conventional versus continuous hyperfractionated accelerated radiotherapy (CHART). EXPERIMENTAL DESIGN: Tumor material was obtained from 402 patients. Immunohistochemistry was used to assess Ki-67, CD31, p53, Bcl-2, and cyclin D1 expression. A hierarchical clustering algorithm with a Bayesian information criterion was used to group tumors with similar marker expression; resulting expression profiles were then compared in terms of their difference in outcome after CHART and conventionally fractionated radiotherapy. RESULTS: Molecular marker profile was an independent prognostic factor for locoregional control. This was confirmed in multivariate analysis, including clinical variables such as tumor and nodal status, primary site, histological grade, age, and gender (P < 0.001 and P = 0.006 for local and nodal relapse, respectively). In particular, Bcl-2-positive tumors responded significantly better than average in both arms of the trial. Tumors negative for p53- and Bcl-2, with high and randomly patterned Ki-67 expression, responded worse than average with no benefit from CHART. Tumors with similarly negative p53 and Bcl-2, but low Ki-67 staining, with an organized pattern, benefit significantly from CHART schedule. CONCLUSIONS: This study demonstrates the potential of molecular profiles to predict radiotherapy response of head and neck squamous cell carcinoma and for treatment stratification. Distinct expression profiles correlate with three distinct clinical phenotypes, including good locoregional control, poor locoregional control, and an outcome strongly dependent upon fractionation schedule

Pre-treatment proliferation and the outcome of conventional and accelerated radiotherapy.

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