Abstract only e18564 Background: IGF-1 and IGF-2 are powerful mitogenic factors with anti-apoptotic effect. Their overproduction leads to neoangiogenesis and metastasis. Monitoring the level of these factors can serve as a potential predictive tool. The purpose of the study was to study blood levels of IGF-1 and IGF-2 in patients with squamous cell carcinoma (SCC) of the oral cavity depending of the efficacy of chemotherapy (CT) and cetuximab. Methods: The study included 50 patients with squamous cell carcinoma of the oral cavity T3-4N0-1M0, stage III-IV. The main group (n = 30) received 2 CT cycles with cetuximab: cisplatin 100 mg/m 2 , intravenously, day 1, 5-fluorouracil 1000 mg/m 2 /day, intravenously, 96-hour continuous infusion, in combination with cetuximab 400 mg/m2 on day 1 in a loading dose, then 250 mg/m2 on days 8 and 15. The control group (n = 20) received 2 CT cycles: intravenous cisplatin 100 mg/m 2 on day 1, intravenous 5-fluorouracil 1000 mg/m 2 /day, 96-hour continuous infusion on days 1-4. Results were compared with the values in 20 non-cancer donors. Levels of IGF-1 (mcg/L) and IGF-2 (ng/mL) were measured in the blood serum by ELISA using standard test systems (Mediagnost, Germany). Statistical analysis of results was performed using the Statistica 6.0 program (Stat-Soft, 2001). Results: Before treatment, levels of IGF-1 and IGF-2 in patients were lower than in donors by 53.5% and 20.3%, respectively. In patients with partial regression after CT, IGF-1 levels significantly increased by 33% (p < 0,05), compared to the values before treatment, while IGF-2 was both within donor and initial values and the IGF-1/IGF-2 ratio was similar to the initial level but 33.3% lower than in donors. The patients in the main group with partial regression normalized IGF-1 levels increasing it compared to initial values – by 87%. IGF-2 levels did not differ statistically significantly from the initial values and were 32.5% lower than in donors. The IGF-1/IGF-2 ratio was 58% higher than before treatment. Conclusions: CT and cetuximab normalized blood levels of IGF-1 in oral cancer patients with partial tumor regression.