Treating nephroblastoma in Rwanda: using International Society of Pediatric Oncology  guidelines in a novel oncologic care model by Shyirambere, C, Xu, MJ, Elmore, SN, Fadelu, T, May, L, Tapela, N, Umuhizi, DG, Uwizeye, FR, Driscoll, C, Muhayimana, C, Hategekimana, V, Rubagumya, F, Nzayisenga, I, Shulman, LN, Mpunga, T, Lehmann, LE