Addition of docetaxel or bisphosphonates to standard of care in men with localised or metastatic, hormone-sensitive prostate cancer: a systematic review and meta-analyses of aggregate data

Abstract

Background: Results from large randomised controlled trials combining docetaxel or bisphosphonates with standard of care in hormone-sensitive prostate cancer have emerged. In order to investigate the effects of these therapies and to respond to emerging evidence, we aimed to systematically review all relevant trials using a framework for adaptive meta-analysis.

Methods: For this systematic review and meta-analysis, we searched MEDLINE, Embase, LILACS, and the Cochrane Central Register of Controlled Trials, trial registers, conference proceedings, review articles, and reference lists of trial publications for all relevant randomised controlled trials (published, unpublished, and ongoing) comparing either standard of care with or without docetaxel or standard of care with or without bisphosphonates for men with high-risk localised or metastatic hormone-sensitive prostate cancer. For each trial, we extracted hazard ratios (HRs) of the effects of docetaxel or bisphosphonates on survival (time from randomisation until death from any cause) and failure-free survival (time from randomisation to biochemical or clinical failure or death from any cause) from published trial reports or presentations or obtained them directly from trial investigators. HRs were combined using the fixed-effect model (Mantel-Haenzsel).

Findings: We identified five eligible randomised controlled trials of docetaxel in men with metastatic (M1) disease. Results from three (CHAARTED, GETUG-15, STAMPEDE) of these trials (2992 [93%] of 3206 men randomised) showed that the addition of docetaxel to standard of care improved survival. The HR of 0·77 (95% CI 0·68-0·87; p<0·0001) translates to an absolute improvement in 4-year survival of 9% (95% CI 5-14). Docetaxel in addition to standard of care also improved failure-free survival, with the HR of 0·64 (0·58-0·70; p<0·0001) translating into a reduction in absolute 4-year failure rates of 16% (95% CI 12-19). We identified 11 trials of docetaxel for men with locally advanced disease (M0). Survival results from three (GETUG-12, RTOG 0521, STAMPEDE) of these trials (2121 [53%] of 3978 men) showed no evidence of a benefit from the addition of docetaxel (HR 0·87 [95% CI 0·69-1·09]; p=0·218), whereas failure-free survival data from four (GETUG-12, RTOG 0521, STAMPEDE, TAX 3501) of these trials (2348 [59%] of 3978 men) showed that docetaxel improved failure-free survival (0·70 [0·61-0·81]; p<0·0001), which translates into a reduced absolute 4-year failure rate of 8% (5-10). We identified seven eligible randomised controlled trials of bisphosphonates for men with M1 disease. Survival results from three of these trials (2740 [88%] of 3109 men) showed that addition of bisphosphonates improved survival (0·88 [0·79-0·98]; p=0·025), which translates to 5% (1-8) absolute improvement, but this result was influenced by the positive result of one trial of sodium clodronate, and we found no evidence of a benefit from the addition of zoledronic acid (0·94 [0·83-1·07]; p=0·323), which translates to an absolute improvement in survival of 2% (-3 to 7). Of 17 trials of bisphosphonates for men with M0 disease, survival results from four trials (4079 [66%] of 6220 men) showed no evidence of benefit from the addition of bisphosphonates (1·03 [0·89-1·18]; p=0·724) or zoledronic acid (0·98 [0·82-1·16]; p=0·782). Failure-free survival definitions were too inconsistent for formal meta-analyses for the bisphosphonate trials.

Interpretation: The addition of docetaxel to standard of care should be considered standard care for men with M1 hormone-sensitive prostate cancer who are starting treatment for the first time. More evidence on the effects of docetaxel on survival is needed in the M0 disease setting. No evidence exists to suggest that zoledronic acid improves survival in men with M1 or M0 disease, and any potential benefit is probably small.

Funding: Medical Research Council UK.

Figure 1

Study flow chart CRPC=castrate-resistant prostate cancer. *One trial (STAMPEDE) is eligible to be included in both docetaxel and bisphosphonate comparisons.

Figure 2

Effect of addition of docetaxel to standard of care on survival and failure-free survival (A) Effect of the addition of docetaxel on survival in men with M1 disease. (B) Effect of the addition of docetaxel on failure-free survival in men with M1 disease. (C) Effect of the addition of docetaxel on survival in men with M0 disease. (D) Effect of the addition of docetaxel on failure-free survival in men with M0 disease. NA=event numbers by group not available. SOC=standard of care.

Figure 3

Effect of addition of bisphosphonates to standard of care on survival (A) Effect of the addition of bisphosphonates on survival in men with M1 disease. (B) Effect of the addition of zoledronic acid on survival in men with M1 disease. (C) Effect of the addition of bisphosphonates on survival in men with M0 disease. (D) Effect of the addition of zoledronic acid on survival in men with M0 disease. NA=event numbers by group not available. SOC=standard of care.