Since the era of evidence-based medicine, it has become a matter of course to use statistics to create objective evidence in clinical research. As an extension of this, it has become essential in clinical research to calculate the correct sample size to demonstrate a clinically significant difference before starting the study.Also, because sample size calculation methods vary from study design to study design, there is no formula for sample size calculation that applies to all designs. It is very important for us to understand this. In this review, each sample size calculation method suitable for various study designs was introduced using the R program (R Foundation for Statistical Computing). In order for clinical researchers to directly utilize it according to future research, we presented practice codes, output results, and interpretation of results for each situation.

OBJECTIVE: The chemotherapeutic agent cisplatin (cis-diamminedichloroplatinum (II)) is particularly effective against cervical cancer. The purpose of this study is to elucidate combination effect of cisplatin and green tea extracts on the growth inhibition of TC-1 cell. METHODS: To observe the anti-proliferative effects, we treated different doses of cisplatin (0.1, 0.5, 2.5 uM), GTP (1, 5, 25 ug/ml) and EGCG (25, 50, 100 uM). to TC-1 cells. Also, we treated 0.5 uM of cisplatin and different doses of GTP (1 and 5 ug/ml) or EGCG (25 and 50 uM). Cell viability was scored by use of MTT assay. In addition, E6 gene expression patterns in TC-1 cell were investigated by using RT-PCR. RESULTS: Cell growth inhibition in a dose dependent was observed at the different concentration of ciaplatin, GTP and EGCG. Also, in the groups treated by 0.5 uM of cisplatin and GTP (1 and 5 ug/ml) or EGCG (25 and 50 uM), the inhibition of cell growth showed with 12.2%, 6.9% and 63.4%, 72.2% as compared to the group treated by cisplatin only. In RT-PCR, down regulation of E6 was shown. CONCLUSION: Additive effect of the combination of cisplatin with GTP or EGCG on the inhibition of cell growth was observed. This effect suggests the possibility lowering the concentration of chemotherapeutic drugs, which alleviate the side effect of drugs.
Cell Survival ; Cisplatin* ; Down-Regulation ; Gene Expression ; Guanosine Triphosphate ; Tea* ; Uterine Cervical Neoplasms