Academic Radiation Oncology
Academic Radiation Oncology: Translational Radiobiology Group
Comparison of predicted and clinical response to radiotherapy: a radiobiology modelling study.INTRODUCTION: A model to predict clinical outcome after radiation therapy would be a valuable aid in the effort of developing more tailored treatment regimes for different patients. In this work we evaluate the clinical utility of a model that incorporates the following individually measured radiobiology parameters: intrinsic radiosensitivity, proliferation and number of clonogenic cells. The hypothesis underlying the study was that the incorporation of individually measured tumour parameters in a model would increase its reliability in predicting treatment outcome compared with the use of average population derived data. MATERIAL AND METHODS: Forty-six patients with head and neck tumours were analyzed, the majority of whom received both external beam radiotherapy and brachytherapy. Eighteen patients received external beam treatment alone and statistical analyses were carried out on this subgroup. RESULTS: Four of the 18 patients had a >95% calculated probability of cure and none developed a local recurrence resulting in a negative predictive value of 100% (compared with 67% for population-derived data). The sensitivity of the model in predicting local recurrence was 75% (compared with 38% for population-derived data). Using a model that incorporated individually measured radiobiology data, there was a statistically significant difference in local control levels for patients with >95% and <5% predicted probability of local control (chi(2), p = 0.04). DISCUSSION: This study suggests, therefore, that incorporation of measured biological data within a radiobiological model improves its ability to predict radiation therapy outcome compared with the use of population-derived data.
The degree of circumferential tumour involvement as a prognostic factor in oesophageal cancer.Objective: Tumour length is an adverse prognostic factor in oesophageal cancer. However, the prognostic role of the degree of oesophageal circumference (DOC) involved by tumour with or without resection margin invasion is not clear. This work assessed the relationship between DOC involved by tumour, clinico-pathological variables and prognosis. Methods: The clinico-pathological details of 320 patients who underwent potentially curative oesophagogastrectomy for cancer between 1994 and 2007 were analysed. The DOC involved with tumour measured macroscopically on the resected specimen was classified as small (<2.5cm, n=115), large (>/=2.5cm, n=144) or circumferential (i.e. involving the whole circumference, n=61). Univariate and multivariate survival analyses were carried out. Results: The DOC with tumour was higher in ulcerating tumours than stenosing or polypoidal types (p=0.017). Tumour length, T-stage, neoadjuvant chemotherapy and vascular invasion were independently associated with DOC with tumour on multivariate analysis (p<0.05 for all). DOC >/=2.5cm was an adverse prognostic factor in univariate analysis (p=0.002) with a hazard ratio of 1.52 [95% CI 1.13-2.04] compared with those <2.5cm. Circumferential tumours had a similar prognosis to tumours >/=2.5cm (p=0.60). The prognostic significance of DOC with tumour was lost in multivariate analysis where the factors retaining independence were patient age, T-stage, lymph node metastasis, vascular invasion and positive resection margins. However, when patients were stratified by use of neoadjuvant chemotherapy (n=121), the DOC with tumour retained prognostic significance on multivariate analysis in the 199 patients who did not undergo neoadjuvant chemotherapy (p=0.04). Conclusion: The DOC with tumour appears to provide prognostic information in oesophageal cancer surgery, especially in patients who do not undergo preoperative chemotherapy.