Cellular radiosensitivity of primary head and neck squamous cell carcinomas and local tumor control.

The low dose survival parameters of human tumor cell lines have been shown to correlate with the perceived clinical radiosensitivity of different tumor histologic types. This conclusion has been generated from the analysis of a large number of cell lines and has, therefore, served as the basis for attempts to develop predictive assays of tumor radiocurability. In this study, the tumors from 72 patients with head and neck squamous cell carcinoma have been grown in an adhesive tumor cell assay system and their sensitivity to radiation has been measured. All patients in this study were treated with post-operative radiotherapy, the surgical margins were negative, and any patient that had received chemotherapy was excluded. The average S2 (survival at 2.0 Gy) value of the 72 cultures was 0.33, with the values ranging from 0.11 to 0.91. All patients were evaluated for local tumor control. They have been followed for about 1 year and continued follow-up is still in progress. The average survival at 2.0 Gy of cultures derived from the 12 patients that have had recurrences so far is slightly higher (0.40) than that from those who appear so far to have local tumor control (0.30). Although the general trend is that recurrent tumors yield primary cultures that are slightly more resistant, the difference is not statistically significant.