Upper tract urothelial cancer (UTUC) is a recurrent disease. The current standard treatment for most UTUC patients requires surgery either removing some of the ureter in each operation or radical nephroureterectomy (RNU-removal of kidney and ureter) but the role of minimally invasive & kidney- preserving methods is increasing. The use of TOOKAD (padeliporfin) was investigated in a Phase 1 clinical study in the minimally-invasive treatment of UTUC with the goal of identifying safe laser/light exposure and signs that the tumor has been reduced or eliminated. Early results from this study have been highly promising, revealing the effects of tumor removal with a positive safety profile, indicating the potential role of TOOKAD (padeliporfin) in the treatment of low-grade UTUC disease. This Phase 3 study is designed to provide confirmation of the observed Phase 1 findings. Patients are expected to remain in the study for 25 to 28 months. Participation in this study will include up to 9 study visits to Hershey Medical Center and 2 phone visits.