Renal pelvis cancer is a rare cancer. The data presented in the literature indicate that timely diagnosis and early surgical treatment, often in combination with chemotherapy and radiation therapy, are the key to success. This is due to the high metastatic potential of this type of tumor, rapid spread to the bladder and, as a consequence, unsatisfactory long-term results. This paper presents a rare case of papillary cancer of the renal pelvis, which has completely spread throughout the lumen of the left ureter and into the cavity of the bladder. The duration of the disease in the absence of regional and distant metastasis is surprising. For the first time, the dynamics of tumor tissue growth from the pelvis to the bladder over 3 years in the absence of treatment is presented using a clinical example.