[Neoadiuvant teleradiotherapy decreases cancer tissue and serum concentration of prostaglandin E2 and cyclooxygenase-2 expression in patients with rectal cancer].

UNLABELLED: The carcinogenesis of colorectal cancer involves many factors, which modify the functioning of cells and can include prostaglandins. Resection of tumours and/or radiotherapy provide potentially curative therapy for cancer of the rectum.

AIM: The aim of the study was to asses the effects of neoadiuvant teleradiotherapy on PGE2 concentrations in the serum and in the resected bowel tissue as well as on COX-2 gene expression in patients with rectal cancer.

MATERIALS AND METHODS: Group I (n=20) included patients with resectable tumour (T1-2,No) treated exclusively by surgery, and group II (n=20) - patients with resectable tumours (T3) and nonresectable ones (T4). All the patients out of group II were put to the surgery after the previous teleradiotherapy applied to them. PGE2 concentrations were examined using the RIA method, while COX-2 mRNA expression was analyzed with the use of the PCR method.

RESULTS: PGE2 serum concentrations in the group I prior to the resection did not differ from PGE2 concentrations in the group II prior to the resection (p=0,9488). However, radiation had caused reduction of PGE2 serum concentration prior to the resection in patients from the group II in comparison with the group I (p=0,0115). PGE2 serum concentrations after resection in the group I did not differ significantly from PGE2 concentrations in group II after resection (p=0,4511) (two-factor analysis of variation with interaction, p=0,3117). Radiotherapy did not change significantly PGE2 concentrations in the tumour and margin (two-factor analysis of variations with interaction, p=0,3137). The comparison between the number of patients who showed higher COX-2 mRNA expression in tumour than in the margin in the group I and II, did not reveal differences (p=0,6614).

CONCLUSIONS: Neoadiuvant teleradiotherapy decreased PGE2 concentration in the serum, thus showed similar effect as tumour resection.