Intermittent androgen ablation in patients with biochemical failure after pelvic radiotherapy for localized prostate cancer

The role of intermittent androgen deprivation therapy in the management of biochemically recurrent or metastatic prostate cancer

Androgen deprivation therapy (ADT) is a well-established treatment for locally advanced, biochemically recurrent and metastatic prostate cancer. However, it is associated with significant side effects including hot flashes, loss of libido and erectile function, muscular atrophy, metabolic abnormalities, and osteoporosis. In attempt to mitigate the side effects of ADT while retaining the oncological benefits, an approach of intermittent ADT (IAD) has been investigated. IAD involves alternating periods of treatment with intervals off treatment to allow hormone recovery. PSA thresholds are triggers for withdrawing and reinitiating therapy. Potential advantages of IAD include improved quality of life with fewer side effects and reduced cost. Delays in the development of hormone resistance have not been demonstrated clinically. The appropriate use of IAD requires patient selection and close monitoring of quality of life and disease status. This review presents the most recent evidence on the role of IAD in the management of prostate cancer.

The role of intermittent androgen suppression in biochemically recurrent or newly diagnosed metastatic prostate cancer

PURPOSE OF REVIEW

To review the current status of intermittent androgen suppression in the management of biochemically recurrent or newly diagnosed metastatic prostate cancer with respect to two recently reported multicenter phase III randomized trials.

RECENT FINDINGS

The Canadian lead trial for men with biochemically recurrent prostate cancer after definitive radiotherapy (National Cancer Institute of Canada Clinical Trials Group PR7) randomized 1386 men and found a hazard ratio for death of 1.03 at a median follow-up of 6.9 years, declaring intermittent therapy noninferior to continuous for the trial algorithm. Over the same time frame, the South West Oncology Group (SWOG) compared continuous to intermittent therapy in metastatic prostate cancer. Although results were very similar in absolute terms, at 9.8 years follow-up, the hazard ratio for death was 1.1 in favor of the continuous approach. Intermittent therapy could not be declared noninferior. Both trials reported improved quality of life in the intermittent arms.

SUMMARY

There is a small increased risk for death from prostate cancer with the use of intermittent androgen suppression in both these patient populations. This situation may be especially true for higher Gleason score tumors (8-10) and in men with symptomatic bone metastases. Quality-of-life benefits may make this approach worthwhile for some individuals.

Advanced prostate cancer treated with intermittent or continuous androgen deprivation in the randomised FinnProstate Study VII: quality of life and adverse effects

BACKGROUND

Intermittent dosing may reduce the adverse events (AEs) of androgen-deprivation therapy (ADT).

OBJECTIVE

To compare intermittent androgen deprivation (IAD) and continuous androgen deprivation (CAD) with regard to health-related quality of life (QoL).

DESIGN, SETTING, AND PARTICIPANTS

A total of 852 men with advanced prostate cancer (PCa) were enrolled to receive goserelin acetate 3.6 mg every 28 d for 24 wk. A total of 554 patients whose prostate-specific antigen (PSA) decreased to <10 ng/ml or by ≥50% (<20 ng/ml at baseline) were randomised to IAD or CAD.

INTERVENTION

In the IAD arm, ADT was resumed for at least 24 wk whenever PSA increased >20 ng/ml or above baseline.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

QoL was monitored with a validated Cleary 30-item questionnaire and analysed by the Mann-Whitney U test, 0.5 standard deviation rule, and repeated measures analysis of variance. AEs and adverse drug reactions (ADRs) were analysed by the chi-square test.

RESULTS AND LIMITATIONS

Median follow-up was 65 mo. Significant differences in QoL emerged in activity limitation, physical capacity, and sexual functioning, favouring IAD. No significant differences emerged in the prevalence of AEs: 87 patients in the IAD arm (31.8%) and 95 in the CAD arm (33.9%) had cardiovascular (CV) AEs (p=0.59), with 25 (9.1%) and 29 (10.4%) withdrawn (p=0.62), and 21 (7.7%) and 24 (8.6%) dying because of a CV event (p=0.70), respectively; bone fractures occurred in 19 (6.9%) and 15 (5.4%) patients (p=0.44), respectively. Hot flushes or night sweats were the most common ADRs (47.1% vs 50.4%; p=0.44). Erectile dysfunction (15.7% vs 7.9%; p=0.042) and depressed mood (2.2 vs 0%; p=0.032) were more common in the IAD arm.

CONCLUSIONS

IAD showed benefits in the treatment of advanced PCa with respect to QoL. The prevalence of AEs was not significantly lower with IAD.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00293670.

Potential benefits of intermittent androgen suppression therapy in the treatment of prostate cancer: a systematic review of the literature

CONTEXT

The well-known side-effect profile of androgen-deprivation therapy (ADT) has significant quality-of-life (QoL) implications. Intermittent androgen deprivation (IAD) alternates androgen blockade with treatment cessation to allow hormonal recovery between treatment cycles, thus potentially improving tolerability and QoL.

OBJECTIVE

To evaluate available evidence regarding the efficacy and tolerability of IAD and assess its value in the treatment of prostate cancer (PCa).

EVIDENCE ACQUISITION

Key phase 2/3 clinical trials of IAD in PCa published within the last 10 yr were identified on Medline using the terms prostatic neoplasms [MeSH], intermittent androgen suppression, intermittent hormonal deprivation, intermittent androgen deprivation, and intermittent hormonal therapy. Abstracts from trials reported at 2008-2009 conferences were also included.

EVIDENCE SYNTHESIS

Data from 19 phase 2 studies are discussed with respect to prostate-specific antigen values for treatment suspension/reinitiation, treatment regimens, cycle lengths, testosterone normalisation, and tolerability. Outcome data were promising: Most trials reported an improvement in QoL during the off-therapy periods. Interim data from eight phase 3 trials comparing IAD and continuous androgen deprivation (CAD) support the phase 2 results. IAD generally showed comparable efficacy to CAD with respect to various outcomes, including biochemical progression, progression-free survival, and overall survival. However, IAD was significantly better than CAD with respect to 3-yr risk of progression in one study, and it demonstrated tolerability benefits, particularly with respect to sexual function. Patients most likely to benefit from IAD and factors predictive of poor response are also discussed.

CONCLUSIONS

IAD seems to be as effective as CAD while showing tolerability and QoL advantages, especially recovery of sexual potency; however, there are as yet insufficient data to determine whether IAD has the potential to prevent or reverse the long-term complications associated with ADT.

Das Lokalrezidiv des Prostatakarzinoms: Hormontherapie

BACKGROUND

The majority of patients receive HT after biochemical progression despite primary therapy of prostate cancer with curative intent. It is difficult to differentiate at a low rise in PSA level, e.g., <or=1 ng/ml, between local or systemic recurrence.

MATERIAL AND METHODS

The PSA doubling time (DT) is the most reliable surrogate parameter to decide if HT should be initiated. In practice, however, the trigger PSA is used instead. The latter is closely related to the timing of HT. A high PSA is a contraindication for local salvage therapy. Intermittent HT is apparently as effective as continuous HT and shortens the time of HT exposure.

RESULTS

Traditional HT employs a LHRH agonist, however, the side effect profile is a disadvantage due to the long duration of this treatment, e.g., sarcopenia, osteopenia, or even cognitive impairment. The alternative is nontraditional HT: nonsteroidal antiandrogen (AA) alone such as bicalutamide 150 mg or peripheral androgen blockade (AA plus 5alpha-reductase inhibitor).

CONCLUSION

Even after a long duration of the latter HT the side effects are less pronounced (gynecomastia) and treatable. Particularly in patients with high-risk primary tumors [Gleason score 7(4+3)-10 or an initially high PSA], nontraditional HT may be followed by secondary HT.