The lack of correlation between proliferation (Ki-67, PCNA, LI, Tpot), p53expression and radiosensitivity for head and neck cancers

A study was made of the relationship between measurements of radiosensitivi ty versus proliferation and p53 status in head and neck cancers. Inherent t umour radiosensitivity was assessed as surviving fraction at 2 Gy (SF2) usi ng a clonogenic soft agar assay (n = 77). The results were compared to data on proliferation obtained by both flow cytometry (labelling index (LI), th e potential doubling time (Tpot) n = 55) and immunohistochemistry (Ki-67 an d PCNA; n = 68), together with immunohistochemical p53 expression (n = 68). There were no overall significant differences in the median values of the various parameters analysed for the different sites within the head and nec k region, disease stages. grades of tumour differentiation or nodal states. A subgroup analysis showed that oropharyngeal (n = 22) versus oral cavity (n = 35) tumours were more radiosensitive (P = 0.056) and had a higher Ki-6 7 index (P = 0.001), Node-positive tumours had higher LI (P = 0.021) and a trend towards lower Tpot (P = 0.067) values than node-negative ones. No cor relations were seen between SF2 and any of the parameters studied. The long -standing dogma of an increased radiosensitivity of rapidly proliferating c ells in contrast to slowly proliferating cells was not confirmed. The study shows that parallel measurements of different biological markers can be ob tained for a large number of patients with head and neck cancers. The indep endence of the various parameters studied suggests that there may be potent ial for their combined use as prognostic factors for the outcome of radioth erapy.