SAN FRANCISCO—Patients achieving only near-complete responses to bladder-preserving induction chemoradiotherapy for muscle-invasive bladder cancer fare just as well over the long term as those who achieve complete responses, according to an analysis presented during the 2014 Genitourinary Cancers Symposium.

“There is no apparent difference in the bladder recurrence and salvage cystectomy rates between complete and near-complete responders as judged at the time of cystoscopic evaluation after induction phase of bladder preserving CMT [combined modality therapy],” reported radiation oncologist Timur Mitin, MD, PhD, of the Massachusetts General Hospital in Boston, MA, and colleagues.

“It is appropriate to recommend that patients with Ta or Tis after induction chemo-radiotherapy continue with bladder sparing therapy,” the researchers concluded.

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Bladder preserving CMT for muscle-invasive bladder cancer involves transurethral resection and concurrent chemoradiotherapy administered in two phases, the authors noted: induction chemoradiotherapy involves 40 Gy and assessment of tumor response using cystoscopic biopsy and urine cytology. Persistent disease prompts salvage surgical cystectomy; patients with complete or near-complete responses to induction therapy proceed to consolidation chemoradiotherapy (64 Gy).

“We performed a pooled analysis of 119 eligible patients with muscle-invasive bladder cancer enrolled on RTOG [Radiation Therapy Oncology Group] trials 9906 and 0233, who were classified as having a complete (T0) or near-complete (Ta or Tis) response after induction chemo-RT and completed consolidation with a total radiotherapy dose of at least 60 Gy,” Dr. Mitin’s team explained.

Of the 119 patients, 101 (85%) achieved complete responses after induction therapy, while 18 (15%) achieved partial responses. All patients proceeded to consolidation therapy.

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At a median follow-up of 5.9 years, there was no significant difference in bladder cancer recurrence among patients who had achieved complete or partial responses (36% vs. 28%; P = 0.52, not significant). Nor were disease-specific, bladder-intact, tumor-recurrence–prompted late salvage cystectomy, or overall survival rates, different between the two groups.

The study was funded by the US National Cancer Institute (NCI).

The 2014 Genitourinary Cancers Symposium is sponsored by the the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), and the Society of Urologic Oncology (SUO).

References

  1. Mitin T, George A, Zietman AL, et al. Abstract 284. Presented at: 2014 Genitourinary Cancers Symposium. Jan. 30-Feb. 1, 2014; San Francisco.