Single Tissue Samples from Head and Neck Squamous Cell Carcinomas are Representative Regarding the Entire Tumor's Chemosensitivity to Cisplatin and Docetaxel

Background: In multimodal therapy concepts for advanced head and neck squamous cell carcinoma (HNSCC), a valid predictive assay for the quick detection of efficient chemotherapeutic agents is desirable. Questionable so far was whether tissue samples of about 100 mg correctly reflect the chemoresponse of a whole HNSCC. This was proven using an ex-vivo colony-forming assay. Materials and Methods: Of 14 HNSCC, 3 biopsies each were taken from separate sites, minced, and collagenase digested. HNSCC digests were added to microtiter plates containing serial dilutions of chemotherapeutic agents or medium as control. After 72-h incubation, wells were washed and cultures methanol-fixed before Giemsa-staining. Epithelial colonies were counted. Results: 11/14 HNSCC (78.6%) showed sufficient colony formation allowing reliable cut-off detection. Cut-off concentrations (complete chemotherapeutically suppressed colony formation) between 3.3 mu M and >50 mu M cisplatin, and 0.55 mu M and 17.6 mu M docetaxel were detected. Inhibition of colony formation to 50% of colonies detected in controls (IC50) was found between 0.2 mu M and 17.9 mu M cisplatin or 1.5 mu M and 13.7 mu M docetaxel. Cut-off concentrations and IC50 of the HNSCC fragments showed a strong correlation (docetaxel: r > 0.80, p 0.005; cisplatin: r > 0.67, p 0.044), while being only insignificantly different in the t-test for paired samples (docetaxel: p > 0.163; cisplatin: p > 0.167). Conclusion: In most cases, tissue samples of about 100 mg allow a representative assessment of chemoresponse of HNSCC.