The efficiency of propranolol on occurrence and development of 4-nitroquinoline 1- oxide induced squamous cell carcinoma of the tongue in rats

Oral cavity cancers are one of the most frequent neoplasms. Although there have been many reported studies about treatment approach, survival rates in oral cancer patients have been similar for 4-5 decades. Chemoprevention can extend the latency period of carcinogenesis and it seems to be a crucial approach considering complex treatment procedures and high morbidity and mortality rates of oral cancers. Propranolol is a non-selective β-blocker drugs. Many previously reported study showed that this agent can be effective for prevention of cancer development or anticancer therapies by its anti-angiogenesis and β- adrenergic reseptor (β-AR) inhibition action. 4-nitroquinoline 1-oxide model (4NQO) have been frequently used for development new chemoprevention methods for oral carcinogenesis. The aim of this study was to investigate the efficiency of propranolol on 4NQO induced squamous cell carcinogenesis of the tongue in rats. A total of 27 male Sprague Dawley rats were received 50 ppm 4NQO for 20 weeks in drinking water. The other procedures were as follows (n=9 per group) :Group 1, treated with 50 mg/kg/day propranolol by oral gavage; Group 2, following to carcinogesis inducement for 20 weeks, propranolol were applied for 2 weeks; Group 3 (control group), no treatment was applied. Histopathological analysis revealed decreased risk of malignant transformation rates in Group 1 (33.3%) when compared with Group 2 (55.5%) and 3 (77.8%). According to binary system of oral precancerous lesion there were slightly difference between 3 groups regarding to high risk category (Group 1; 11.1%, Group 2 and 3; %22.2) The rates of low risk category were 22.2% in Group 1, 33.3% in Group 2 and 55.5% in Group 3. The statistical comparision was performed by likelihood ratio test and the difference between groups were not statistically significant. (P>0.05) One tumor occurrence was detected for each group. Considering tumor size the sample in Group 3 (1.8 cm) was almost threefold of the sample in Group 1 (0.6 cm) and twofold of the tumor sample in Group 2 (0.9 cm) Hiperkeratinisation and vasodilation degrees were similar for all groups (Median: 2) As we concluded propranolol usage may provide chemoprevention especially in early carcinogenesis stages. Though there advanced studies with larger samples is required for revealing this effect more precisely.