Patients With Near-Complete Response After Induction Therapy May Be Candidates for Bladder-Sparing Therapy
Bladder-sparing approaches are typically reserved for patients with bladder cancer who have a complete response to combined modality induction therapy (radiation plus chemotherapy). A new phase II study suggests that patients with near-complete response should also be considered for bladder-sparing approaches, thereby expanding the pool of patients who can retain their natural bladder.
The study was based on a pooled analysis of two Radiation Therapy Oncology Group (RTOG) trials (9906 and 0233) to determine long-term outcomes among patients with muscle-invasive bladder cancer who undergo induction chemoradiotherapy and achieve complete response or near-complete response. Results were presented at the 2014 Genitourinary Cancers Symposium in San Francisco (Abstract 284).
Although bladder-conservation therapy has been around for about 4 decades, the current backbone of trimodality bladder-preservation approach is maximal transurethral resection of the bladder tumor and radiation plus concurrent chemoradiotherapy followed by cystoscopic evaluation, explained lead author Timur Mitin, MD, PhD, of Massachusetts General Hospital, Boston.
Patients with complete response on cystoscopic evaluation get treated with consolidated chemoradiotherapy, and those who are not in complete response undergo radical cystectomy with or without chemotherapy, he said.
“Historically, complete response after cystoscopic evaluation has been defined as T0 [no tumor], but many physicians have been reluctant to use radical cystectomy in patients with only small amount of tumor or carcinoma in situ [tumor stages, Ta and Tis] following induction,” Dr. Mitin told the audience.
Pooled Analysis
RTOG 9906 was a single-arm, 80-patient trial with relaxed criteria for bladder-sparing approaches, and RTOG 0233 was a phase II trial that included 97 patients. Induction phase and consolidation radiation details were the same on both protocols.
The pooled analysis of outcomes included 119 patients: 101 with complete response (85%) and 18 with near-complete response [Ta or Tis, 15%). Median age was 65 years in RTOG 9906 and 70 years in RTOG 0233. The majority of patients had clinical stage T2 at diagnosis.
At a median follow-up of 5.9 years, 5-year survival was 72% for patients in complete response and 61% for those in near-complete response, which was not statistically different. Disease-free survival was also not statistically different between patients in complete response and near-complete response after induction.
No Significant Difference in Recurrence Rates
Among the 101 patients with complete response, 36 had recurrence (36%); 13 of these patients experienced an invasive recurrence and eventually needed salvage cystectomy. Among 19 patients with near-complete response, there were five recurrences (28%); of these, one patient required late salvage cystectomy.
“Although this is a small retrospective analysis, there is no apparent difference in bladder recurrence and salvage cystectomy rates between complete response and near-complete response at time of cystoscopic evaluation after induction and consolidation bladder-preserving combined-modality therapy. Therefore it is appropriate to recommend that patients with Ta or Tis after induction chemoradiation therapy continue with bladder-sparing therapy,” Dr. Mitin stated.
Study author Howard M. Sandler, MD, MS, FASTRO, reported a consultant or advisory role with Bayer, Medivation, and Sanofi.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
