INFLUENCE OF CONFORMAL RADIOTHERAPY IN COMBINATION WITH RADIOMODIFIERS ON THE CONTENT OF VEGF, COX-2, AND PGE-2 IN BLOOD SERUM OF PATIENTS WITH HEAD AND NECK SQUAMOUS CELL CARCINOMA.

Background: The development of new approaches to modeling tumor radiosensitivity in patients with head and neck squamous cell carcinoma (HNSCC) is an important problem for overcoming tumor radioresistance. New agents for radiomodification are inhibitors of the enzyme cyclooxygenase-2 (COX-2). The study of markers of radioresistance in cancer patients undergoing radiotherapy (RT) in combination with COX-2 inhibitors and chemotherapy may contribute to the effectiveness of RT.

Aim: To determine the effect of conformal RT in combination with radiomodifiers (celecoxib, cisplatin, or their combination) on the content of vascular endothelial growth factor (VEGF), COX-2, and prostaglandin E-2 (PGE-2) in the serum of patients with HNSCC.

Materials and methods: 47 patients with HNSCC were divided into 4 groups: RT in combination with celecoxib and cisplatin, RT with cisplatin, RT with celecoxib, and RT. Patients received radiation treatment on a Clinac 600C linear accelerator. The levels of VEGF, COX-2, and PGE-2 in the serum were determined by enzyme immunoassay.

Results: Blocking COX-2 in patients with HNSCC leads to a decrease in VEGF levels. The largest decrease in VEGF levels was observed in a group treated by RT in combination with celecoxib and cisplatin, indicating a more effective antiangiogenic effect. The changes in the levels of VEGF, COX-2, and PGE-2, which are most pronounced under the combined effect of RT and both radiomodifiers, coincided with an objective response to radiation treatment.

Conclusions: The data obtained indicate the effect of radiomodification on the suppression of angiogenesis, which is most pronounced under the combined effect of RT and both radiomodifiers. The decrease in the levels of PGE- 2, COX-2, and VEGF coincides with the clinical efficacy of radiotherapy according to RECIST 1.1 criteria.