Enhancement of radiosensitivity in head and neck cancer cells by ZD1839 ('IRESSA'), a selective epidermal growth factor receptor tyrosine kinase inhibitor.

Overexpression of epidermal growth factor receptor (EGFR) is frequently observed in many solid tumor types, including head and neck squamous cell carcinomas (HNSCC). Recent laboratory experiments have demonstrated that high EGFR levels correlate with increased tumor resistance to radiation. This study investigated the relationship between EGFR expression levels and radiosensitivity in 5 HNSCC cell lines (HSC2, HSC3, HSC4, SCC25, and Ca9-22) and whether treatment with ZD1839 ('Iressa'), a selective EGFR-tyrosine kinase inhibitor (TKI), would improve tumor cell response to radiotherapy. ZD1839 suppressed the growth of HNSCC cell lines in a dose- and time-dependent manner. Radiosensitivity of these HNSCC cell lines, assessed by a clonogenic survival assay, differed greatly and the expression of EGFR varied. EGFR expression levels (EGFR numbers/cell) correlated with increased tumor resistance to radiation (f[x]= 4.54 X, R2 = 0.715; f[x]: EGFR numbers/cell, X: radiosensitivity; D10). Following exposure of the HNSCC cells to 1.0 microM ZD1839 and radiation (0-10 Gy), greater than additive growth inhibitory effects were observed. These results suggest that ZD1839 could enhance tumor radiosensitivity and inhibit tumor growth after radiation, indicating that this combination could have clinical potential in the treatment of patients with head and neck cancer.

[Non-randomized clinical study comparing chemotherapy plus radiotherapy with radiotherapy alone in neoadjuvant therapy for oral cancer].

Neoadjuvant therapy plays an important role for organ preservation and survival rate in the treatment of oral cancer. We clinically compared the effect of neoadjuvant radiotherapy and chemoradiotherapy in patients with oral cancer. We retrospectively examined 47 patients diagnosed with oral squamous cell carcinoma who underwent neoadjuvant therapy followed by curative surgery in the oral and maxillofacial surgery department of Ehime University Hospital. We divided them into two groups: radiotherapy alone (24 cases) and chemoradiotherapy (23 cases). The patients in the radiotherapy group underwent irradiation of 32.6 +/- 5.0 Gy (mean +/- SD). The patients in the chemoradiotherapy group received a low-dose fraction of cisplatin (8 mg/mm2/day, 5 days a week; total dose: 139.4 +/- 67.1 mg) and 5-fluorouracil (300 mg/mm2/day, 5 days a week; total dose: 5,900 +/- 1,839.8 mg) combined with simultaneous irradiation of 31.0 +/- 3.2 Gy. None of the 24 patients had a complete response to radiotherapy alone and 12 (50%) had a partial response. Six (26%) of the 23 patients had a complete response to chemoradiotherapy and 12 (52%) had a partial response. The primary control rate (82.6%) to chemoradiotherapy was higher than that (67.5%) to radiotherapy alone although no significant difference was found. The 5-year survival rate was 64.3% in the radiotherapy group and 62.8% in the chemoradiotherapy group. The findings of the present study suggest that while the combination of radiation and cisplatin/5-fluorouracil in neoadjuvant therapy for oral cancer may not bring a significant benefit to improve survival rate, the primary local control rate is improved in comparison with radiotherapy alone.