Published in January 2021 in the journal Molecules this study found that "Treatments with CBC+THC or CBD led to cell cycle arrest and cell apoptosis". Apoptosis means the cancer cells essentially kill themselves, or commit suicide.
The study used cannabis extracts that were made from propriety flower cultivars from the Israel Gene Bank using ethanol.
A very interesting aspect of this study is that they isolated (or fractionated) CBC and tested an extract with 86% CBC and 14% THC that had no terpenes. The original extract had only 3% CBC and 26% THC. The high CBC extract fraction with a ratio of (6:1 CBC:THC) was the most effective.
The medical diagnosis is called Urothelial Carcinoma (UC), and it is the most common cancer of the urinary system.
The research paper is here.