Total androgen blockade with Zoladex plus flutamide vs. Zoladex alone in advanced prostatic carcinoma: interim report of a multicenter, double-blind, placebo-controlled study

Systematic review and meta-analysis of monotherapy compared with combined androgen blockade for patients with advanced prostate carcinoma

BACKGROUND

The current systematic review and meta-analysis compared monotherapy and combined androgen blockade in the treatment of men with advanced prostate carcinoma. Outcomes of interest included overall, cancer specific, and progression-free survival; time to treatment failure; adverse events; and quality of life.

METHODS

The literature search identified randomized trials comparing monotherapy (orchiectomy and luteinizing hormone-releasing hormone [LHRH] agonists) with combination therapy using orchiectomy or a LHRH agonist plus a nonsteroidal or steroidal antiandrogen. Dual independent review occurred. The meta-analysis used a random effects model.

RESULTS

Twenty-one trials compared survival after monotherapy with survival after combined androgen blockade (n = 6871 patients). The meta-analysis found no statistically significant difference in survival at 2 years between patients treated with combined androgen blockade and those treated with monotherapy (20 trials; hazard ratio [HR] = 0.970; 95% confidence interval [95% CI], 0.866-1.087). The authors determined a statistically significant difference in survival at 5 years that favored combined androgen blockade (10 trials; HR = 0.871; 95% CI, 0.805-0.942). For the subgroup of patients with a good prognosis, there was no statistically significant difference in survival. Adverse effects leading to withdrawal from therapy occurred more often with combined androgen blockade. To the authors' knowledge there is little evidence published to date comparing the effects of combined androgen blockade and monotherapy on quality of life, but the single randomized trial that adequately addressed this outcome reported an advantage for monotherapy over combined androgen blockade.

CONCLUSIONS

A thorough examination of the usefulness of combined androgen blockade must balance the modest increase in expected survival observed at 5 years against the increased risk of adverse effects and the potential for adversely affecting the patient's overall quality of life.

Diethylstilbesterol revisited: androgen deprivation, osteoporosis and prostate cancer

PURPOSE

It is well described in the urological literature that androgen deprivation can result in accelerated bone breakdown and osteoporosis. Therefore, we evaluate the degree of bone breakdown in patients on conventional androgen deprivation with those on diethylstilbesterol alone or in conjunction with luteinizing hormone releasing hormone agonists or orchiectomy.

MATERIALS AND METHODS

During an 18-month period a total of 54 patients with clinically localized prostate cancer and 24 with benign prostatic hyperplasia were evaluated. All patients with prostate cancer were either treated with external beam radiotherapy without androgen deprivation or were started on androgen deprivation therapy. All patients were prospectively followed and evaluated for serum testosterone and estradiol along with urinary collagen type I cross-linked N-telopeptides. Three separate morning urine samples on 3 separate months were collected on each patient and analyzed for N-telopeptides. To correct for different levels of renal function, all N-telopeptides were measured as a ratio of urinary N-telopeptides/urine creatinine. All patients with any bone or skeletal abnormalities were excluded from study as were those with osseous metastatic disease.

RESULTS

There was a statistically significant (p < 0.05) higher level of urinary N-telopeptides/creatinine in patients on androgen deprivation therapy who were not treated with diethylstilbesterol. The estrogenic effect of diethylstilbesterol protects one from bone resorption. Patients on diethylstilbesterol did not have any higher levels of bone breakdown than patients with benign prostatic hyperplasia or those who never received any androgen deprivation.

CONCLUSIONS

Rapid bone turnover and resorption can be prevented with 1 mg. diethylstilbesterol alone or in conjunction with other modes of androgen deprivation. Therefore, diethylstilbesterol should be considered as monotherpy in men who require long-term antiandrogen therapy.

Maximal androgen blockade for advanced prostate cancer

OBJECTIVES

This systematic review assessed the effect of maximal androgen blockade (MAB) on survival when compared to castration (medical or surgical) alone for patients with advanced prostate cancer.

SEARCH STRATEGY

Randomized controlled trials were searched in general and specialized databases (MEDLINE, EMBASE, Cancerlit, Cochrane Library, VA Cochrane Prostate Disease register) and by reviewing bibliographies.

SELECTION CRITERIA

All published randomized trials were eligible for inclusion provided they (1) randomized men with advanced prostate cancer to receive a non-steroidal anti-androgen (NSAA) medication in addition to castration (medical or surgical) or to castration alone, and (2) reported overall survival, progression-free survival, cancer-specific survival, and/or adverse events. Eligibility was assessed by two independent reviewers.

DATA COLLECTION AND ANALYSIS

Information on patients, interventions, and outcomes were extracted by two independent reviewers using a standardized form. The main outcome measure for comparing effectiveness was overall survival at 1, 2, and 5 years. Secondary outcome measures included progression-free survival and cancer-specific survival. The relationship of specific NSAA on outcome was evaluated. Additionally, the incidence of adverse effects was measured.

MAIN RESULTS

Twenty trials enrolling 6,320 patients were included. The pooled OR for overall survival was 1.03 (95% CI:0.85 to 1.25), 1.16 (95% CI:1.00 to 1.33), and 1.29 (95% CI:1.11 to 1.50) at 1, 2, and 5 years respectively. Overall survival was only significant at 5 years. The risk difference at 5 years was 0.048 (95% CI:0.02 to 0.077) and NNT at 5 years 20.8. Progression-free survival was improved only at 1 year follow-up (OR=1.38) and cancer-free survival was improved only at 5 years (OR=1.22). Adverse events occurred more frequently in those assigned to MAB and resulted in withdrawal in 10%. Quality of life was measured in only one study favored orchiectomy alone (less diarrhea and better emotional functioning in the first 6 months).

REVIEWER'S CONCLUSIONS

MAB produces a modest overall and cancer-specific survival at 5 years but is associated with increased adverse events and reduced quality of life.

Maximum androgen blockade in advanced prostate cancer: a meta-analysis of published randomized controlled trials using nonsteroidal antiandrogens

OBJECTIVES

To assess the survival benefit of maximum androgen blockade (MAB) using nonsteroidal antiandrogens (NSAAs) through meta-analysis of published randomized controlled trials (RCTs).

METHODS

All RCTs comparing treatment with NSAA plus either luteinizing hormone-releasing hormone (LHRH) or orchiectomy versus treatment with LHRH or orchiectomy alone were included if the necessary statistical summaries were present in the publication. Estimates and standard errors of log hazard ratio for overall survival and progression-free survival were derived from published studies using two methods: (1) reconstructing an annual life table from graphical presentations of survival distributions and fitting discrete proportional hazard models, and (2) reconstructing the log hazard ratio from reported P values and numbers of deaths. An alternative set of log hazard ratios was derived from figures presented in a summary report by the Prostate Cancer Trialists' Collaborative Group (PCTCG). Comparative meta-analyses were performed using the random effects approach of DerSimonian and Laird. Additionally, published studies were used in a random-effects-based meta-analysis of objective tumor response.

RESULTS

Nine studies provided enough information to perform a meta-analysis for survival using one of the two methods. Estimates of relative risks (RR) comparing treatment with NSAA plus either LHRH or orchiectomy versus treatment with LHRH or orchiectomy alone with respect to overall survival were 0.78 (95% confidence intervals [CIs] 0.67 to 0.90) using method 1, and 0.84 (95% CI 0.76 to 0.93) using method 2. Sensitivity analyses based on PCTCG data showed that a favorable survival result for MAB was associated with NSAAs but not with steroidal antiandrogens and depended on randomization blinding and overall trial quality. Additionally, random-effects-based meta-analysis of published studies showed a significant increase in time-to-progression (RR = 0.74; 95% CI 0.63 to 0.86) and an increase in objective tumor responses for MAB using NSAAs compared with castration alone (odds ratio = 0.65; 95% CI 0.51 to 0.81; P = 0.00022).

CONCLUSIONS

Inconsistent results have been published about the benefit of MAB in advanced prostate cancer. This meta-analysis supports a beneficial effect for MAB using NSAAs compared with castration alone, and sensitivity analyses suggest that the design of future trials should carefully address issues of patient characterization, randomization blinding, and other study quality issues.

A controlled trial of bicalutamide versus flutamide, each in combination with luteinizing hormone-releasing hormone analogue therapy, in patients with advanced prostate cancer. Casodex Combination Study Group

OBJECTIVES

To compare the efficacy and safety of bicalutamide and flutamide, each used in combination with luteinizing hormone-releasing analogue (LHRH-A) therapy, in patients with untreated metastatic (Stage D2) prostate cancer.

METHODS

Randomized, double-blind (for antiandrogen therapy), multicenter study with a 2 x 2 factorial design. Eight hundred thirteen patients were allocated 1:1 to bicalutamide (50 mg once daily) and flutamide (250 mg three times daily) and 2:1 to goserelin acetate (3.6 mg every 28 days) and leuprolide acetate (7.5 mg every 28 days).

RESULTS

With a median duration of follow-up of 49 weeks, time to treatment failure, the primary endpoint, was significantly (P = 0.005) better for the bicalutamide plus LHRH-A group than for the flutamide plus LHRH-A group. Patients in the flutamide plus LHRH-A group were 34% more likely to fail treatment over the given time period, as indicated by the hazard ratio of 0.749 (95% confidence interval, 0.61 to 0.92) for bicalutamide plus LHRH-A to flutamide plus LHRH-A. Results for secondary endpoints (survival, quality of life, and subjective response) were similar between groups. Diarrhea occurred in 24% of patients in the flutamide plus LHRH-A group, compared with 10% of patients in the bicalutamide plus LHRH-A group (P < 0.001).

CONCLUSIONS

In patients with metastatic prostate cancer, bicalutamide plus LHRH-A is well tolerated and provides superior efficacy to flutamide plus LHRH-A with respect to time to treatment failure. Assessment of the effects of these regimens on longer term survival requires additional time for follow-up.

Some statistical considerations for the interpretation of trials of combined androgen therapy

Since 1989, there have been strongly conflicting opinions regarding the validity of the proposition that an antiandrogen added to standard hormonal therapy could improve the outcome in patients with newly diagnosed metastatic prostate cancer. To some degree, these conflicting opinions arose from misinterpretations of a number of "negative" clinical trials. The misinterpretations happened because these "negative" trials had insufficient statistical power to refute the reported "positive trial", and information illustrating their statistical power was absent from their reports. Thus, readers were not given the necessary information to distinguish between negative and inconclusive results. In addition, many of the negative reports were early analyses of ongoing clinical trials, a practice that always should be avoided. This article reviews and illustrates the statistical principles that are applicable to the interpretation of low-powered negative clinical trials and discusses the design and conduct of clinical trials.

Goserelin acetate with or without flutamide in the treatment of patients with locally advanced or metastatic prostate cancer. The Italian Prostatic Cancer Project (PONCAP) Study Group

From March 1987 to December 1990, 373 patients with stage C and D prostate cancer were randomized to receive either goserelin acetate alone or goserelin acetate plus flutamide. At a median follow-up time of 24 months, there was no significant difference in the response rate, progression-free and overall survival between the two treatment groups. In particular, median time to progression was 18 months in the goserelin arm and 24 months in the combined treatment arm (P = 0.09). However, median time to progression in stage D patients was 12 months in both treatment groups. Median time to death was 32 and 34 months, respectively. The combination regimen produced a more rapid normalisation of prostatic acid phosphatase levels and a prompt relief of bone pain. However, significantly more patients in the combination arm experienced treatment-related side-effects such as diarrhoea and increases in transaminase levels. The concurrent use of goserelin acetate and flutamide does not seem to significantly improve the results that can be achieved with goserelin acetate alone.

Orchiectomy and nilutamide or placebo as treatment of metastatic prostatic cancer in a multinational double-blind randomized trial

The efficacy and tolerance of the nonsteroidal antiandrogen nilutamide in the treatment of prostatic cancer were studied in a large double-blind clinical trial initiated in 1986. Patients with metastatic prostatic cancer without prior endocrine manipulation underwent orchiectomy and were randomized to 1 of 2 groups receiving nilutamide (225 patients) or placebo (232). Nilutamide and placebo were evaluated for efficacy in 207 and 216 patients, respectively. Progression-free survival was significantly longer in the nilutamide group (median time to progression 20.8 months on nilutamide and 14.9 months on placebo, p = 0.005). Median time to death from prostatic cancer was 30.0 months in the placebo group and 37 months in the nilutamide group. Objective regressions were higher in the nilutamide group (41%) than in the placebo group (24%). Significant differences in favor of the nilutamide group were found at several intervals for bone pain, prostatic acid phosphatase, prostate specific antigen, alkaline phosphatase and bone scan isotope uptake. Nilutamide and orchiectomy constitute a more effective treatment for metastatic prostatic cancer than orchiectomy alone, and the adverse effects of nilutamide, usually minor, are outweighed by the significant improvements in most disease measures and progression-free survival.