SAN FRANCISCO – Patients with muscle-invasive bladder cancer who have a near-complete response to induction chemoradiation can safely skip a cystectomy, suggested a study reported at the 2014 Genitourinary Cancers Symposium sponsored by the American Society of Clinical Oncology.
Researchers led by Dr. Timur Mitin, a radiation oncologist at Massachusetts General Hospital in Boston, conducted a pooled analysis of 119 patients from two Radiation Therapy Oncology Group (RTOG) trials that tested trimodality therapy, whereby patients undergo maximal transurethral resection of the bladder tumor (TURBT), induction chemoradiation, cystoscopic evaluation of response, and consolidation chemoradiation, with or without adjuvant chemotherapy.
Dr. Timur Mitin
In contrast to the historical practice of allowing only patients having a complete response (T0) to induction chemoradiation to proceed with bladder-sparing therapy, the RTOG trials allowed patients having a near-complete response (Ta or Tis) to do the same.
Results showed that, after a median follow-up of almost 6 years, there were no significant differences between the complete and near-complete responders with respect to rates of bladder recurrence, salvage cystectomy, and overall survival, Dr. Mitin reported.
"Many physicians have been reluctant to subject patients to radical cystectomy if, after the induction chemoradiation therapy, they find a very small amount of superficial tumor, Ta or Tis," he commented. On the basis of these patients’ similarly good outcomes, "we recommend that patients with a near-complete response to the induction phase continue with their bladder-sparing therapy."
"I think this was a wonderful analysis," session cochair Dr. Jason A. Efstathiou, also of Massachusetts General Hospital, said in an interview.
"The RTOG has a long history of exploring bladder-sparing trimodality therapy as an option for select patients. If you select those patients well, as this abstract suggested – those who have a complete response or a near-complete response to induction chemoradiation – these patients do in fact very well. So we do believe that, for the right patient, trimodality therapy is an appropriate option, an option to up-front cystectomy. And I think his data [were] very reassuring: For patients who respond well to such treatment initially, they have a very good chance of doing well in the long term and even being cured," he said.
Dr. Jason Efstathiou
"Ultimately, what will be practice changing is the continued multidisciplinary approach to this disease, which means newly diagnosed patients with muscle-invasive disease are seen by urologic surgeons, by medical oncologists, and by radiation oncologists, and that sort of a consensus plan is developed that the patient chooses. So that movement will be practice changing," Dr. Efstathiou added. "And I think patient advocacy – patients learning of trimodality therapy as an option for up-front treatment – will also play a big role in perhaps the increased use of this management strategy."
The study patients were treated on RTOG 9906 (the first trial to relax the response criteria for allowing patients to go on to consolidation therapy) and RTOG 0233.
Pooled analyses compared 101 patients who had a complete response (T0) with 18 patients who had a near-complete response (Ta or Tis) to induction chemoradiation, all of whom were treated with bladder-sparing trimodality therapy.
Baseline demographic and clinical characteristics did not differ significantly between the complete responders and the near-complete responders, Dr. Mitin reported.
After a median follow-up of 5.9 years, the two groups did not differ significantly with respect to rates of any bladder recurrence (36% vs. 28%) or, specifically, an invasive bladder recurrence (36% vs. 20%).
The groups also were statistically indistinguishable with respect to rates of salvage cystectomy, disease-specific survival, and bladder-intact survival, as well as overall survival (72% vs. 61%).
Dr. Mitin disclosed no conflicts of interest related to the research.