THE POTENTIAL ROLE OF HSP70 AS AN INDICATOR OF RESPONSE TO RADIATION AND HYPERTHERMIA TREATMENTS FOR RECURRENT BREAST-CANCER

Twenty-three patients with recurrent breast cancer participating in a Phase III trial evaluating radiotherapy (XRT) with or without hyperthe rmia (HT) were included in a parallel study, of heat shock protein (hs p) expression. The patients had core biopsies and/or fine needle aspir ates (FNA) performed on their tumours, before and after treatment. The se were analysed for hsp content using immunohistochemical staining wi th a monoclonal antibody to the inducible form of hsp70. The proportio n of samples containing identifiable cancer cells was greater for the core biopsy specimens (80%) than with FNA (60%). Staining intensity wa s analysed using either the majority score, i.e. the staining intensit y (on a relative scale from 0 to 3) for the largest proportion of tumo ur cells, or the arithmetic score, which is the sum of the product of percentage of tumour cells and their staining intensity. The staining intensity for hsp's after treatment correlated inversely with the prob ability of attaining a complete response (CR). Specifically, the media n and maximum scores for the biopsy specimens were significantly inver sely related to the probability of attaining CR. The results suggest t hat this technique may be useful in predicting for thermotolerance dev elopment, though more data is needed to confirm the utility of the tec hnique. Results from this study corroborate data from other clinical s tudies which suggest that tumours with elevated hsp levels may demonst rate resistant biologic behaviour.