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Muscle-invasive bladder cancer treated with external beam radiotherapy: prognostic factors
A Pollack1, G K Zagars, D A Swanson
1Department of Clinical Radiotherapy, University of Texas-M.D. Anderson Cancer Center, Houston 77030.
Purpose:
To determine the relationship of several potential prognostic factors to the outcome measures of pelvic control, freedom from metastases, and overall survival for bladder cancer patients treated with definitive external beam radiotherapy.
Methods And Materials:
The records of 135 patients treated with high-dose, planned continuous-course, external beam radiotherapy for muscle-invasive transitional cell bladder cancer were reviewed. These patients were treated to an average total dose of 6588 +/- 475 cGy with an average fractional dose of 207 +/- 18 cGy using megavoltage. Median potential follow-up for all patients, including those who died, was 249 months.
Results:
The actuarial results at 5 year were 31% pelvic control, 58% freedom from metastases, and 26% overall survival. In the univariate analyses, several factors were correlated with disease outcome including clinical stage, tumor morphology, gross total transurethral resection (TURBT), findings at bimanual exam after TURBT, clinical perivesical extension, age, and clinical complete response at first follow-up cystoscopy (Clinical-CR). A Cox proportional hazards model revealed that only Clinical-CR was independently predictive of pelvic control. In terms of freedom from metastases, only Clinical-CR and clinical stage were significantly associated with outcome in the multivariate analysis. When the multivariate analysis was restricted to T2 and T3 tumors only, then clinical perivesical extension replaced stage as being associated with freedom from metastases. The only factors significantly related to overall survival in the Cox proportional hazards model were Clinical-CR, age, and complete TURBT; stage was of borderline significance when only pretreatment factors were considered.
Conclusions:
Clearly, the most important prognostic factor was Clinical-CR. The pretreatment factors of stage, clinical perivesical extension, and gross total TURBT also correlated with outcome, but, to a lesser degree. For patients medically unfit for radical cystectomy radiotherapy is a viable option, particularly for selected patients. Patients with T4 tumors are poor candidates for definitive radiotherapy and should be treated palliatively if they cannot tolerate systemic therapy.