I am reposting for you my spreadsheet hereunder As lightrock said, you need precise numbers because the mere one event in one arm or the other matters a lot CVM initial soc survival model : 55% Y3, 43% Y5 was way too pessimistic (tab1). I assumed a more conservative approach on tab2 (63% Y3 / 54% Y5). This is for the inclusion criteria of the study : stage III and IVa (non metastatic) H&N cancers. Tab 4 is same model as Tab2 with events dates matching real events as measured in feb 2017 and 2018 (and better survival : end date oct 2019) https://docs.google.com/spreadsheets/d/1qW36sMXgKvx2_76GPF3fjmXFYApgsOUq0vU1qlumz6w/edit#gid=1323197717