Research Shines Light on Bladder-Sparing Treatment of Muscle-invasive Bladder Cancer

In about 1 in 5 patients with urothelial cancer in the bladder (which is where the vast majority of urothelial cancer occurs), the cancer has grown into the muscle that forms of the bladder’s walls.

Removing the part of the bladder affected by the cancer — partial cystectomy — or the entire bladder— radical cystectomy — is one way to treat muscle-invasive bladder.

But there is another option, transurethral resection of bladder tumor (TURBT), that keeps the bladder intact and is the treatment used for less serious cases of urothelial cancer that haven’t invaded the bladder wall muscle. In TURBT, the surgeon removes the cancerous tissue, but not the healthy tissue around it, with an instrument that is inserted into and up the ureter. Because the procedure is done through the ureter, there are no incisions, which speeds recovery and reduces side effect. Patients with muscle-invasive bladder treated with TURBT are also usually treated with chemotherapy because there’s a good chance that cancer isn’t limited to the area reached by TURBT.

Using TURBT for muscle-invasive urothelial cancer has been an option of years; there’s good evidence behind the bladder-sparring treatment strategy. But there have been questions about when it should be preferred and so some hesitancy about it.

Research results from a phase 2 trial presented at the 2021 annual meeting of the American Society of Clinical Oncology may help begin to clarify TURBT’s role as a treatment choice for patients with muscle-invasive bladder cancer. In interviews, Matthew D. Galsky, M.D., a professor of medicine and director of genitourinary medical oncology at Mount Sinai’s Tisch Cancer Institute, spoke of “new dawn” in bladder-sparing treatment.

The phase 2 trial included 76 patients whose muscle-invasive bladder cancer was treated with TURBT and four cycles of a chemotherapy combination that included gemcitabine, cisplatin and Opdivo (nivolumab), a programmed death-1 (PD-1) inhibitor and one of the relative new generation of cancer drugs that recruit the immune system into fighting off the disease.

The results that Galsky and his colleagues reported show that 31 of the 64 (45%) patients who completed the four cycle shad a complete response, which was defined no bladder cancer or cancer that had been reduced so that it was no longer growing into the muscular wall of the bladder.

The treatment wasn’t, though, entirely durable. After a median follow-up period of 13.7 months, eight of the 31 patients who had a complete response had local recurrence and six of those underwent cystectomy.

They also noted that a high (10 or greater) tumor mutational burden and a mutant ERCC2 gene (which is associated with sensitivity to the cancer-fighting effects of cisplatin) were associated with a complete reponse.

“TURBT + gemcitabine, cisplatin plus nivolumab achieves stringently cCR (clinical complete reponse) in a large subset of patients with MIBC (muscle-invasive bladder cancer),” they wrote in the conclusion of the abstract of the presentation at the ASCO meeting, which was held virtually from June 4 to June 8.