Does short-term androgen deprivation substitute for radiation dose in the treatment of high-risk prostate cancer?

[Combination of radiotherapy and androgen deprivation therapy for localized prostate cancer]

Combination of radiotherapy and androgen deprivation is now considered as the standard of care for patients with a localized prostate cancer but poor prognosis factors. Two groups of randomized trials have led to this recommendation: some have compared radiotherapy alone versus hormonal treatment and radiotherapy: these trials demonstrated, now with a long follow-up, an improvement in 10-year survival for the combined treatment. Three recent trials compared androgen deprivation alone or combined with radiotherapy; a benefit in survival was also demonstrated in favour of the combination. Some questions remained concerning the optimal duration of hormonal treatment, in view of its potential side effects. Patients in the intermediate prognostic groups could receive a short-term androgen deprivation, but those with a high Gleason score must be treated with a long-term hormonal treatment. Modalities of radiotherapy, regarding volumes and dose must also be précised in the next years.

The impact of increasing dose on overall survival in prostate cancer

PURPOSE

To assess the impact of increasing dose on overall survival (OS) for prostate cancer patients.

METHODS

Treatment data were obtained on more than 20,000 patients in the National Oncology Data Alliance®, a proprietary database of merged tumor registries, who were treated for prostate cancer with definitive radiotherapy between 1995 and 2006. Eligible patients had complete data on total dose, T stage, use and timing of androgen deprivation therapy (ADT), and treatment start date (n = 20,028). Patients with prior malignancies were excluded.

RESULTS

On multivariate analysis, dose, T stage, grade, marital status, age, and neoadjuvant ADT were significant predictors of OS. Hazard ratios for OS declined monotonically with increasing dose, reaching 0.63 (95 % Confidence Interval 0.53-0.76) at ≥80 Gy. On subset analysis, neoadjuvant ADT significantly improved OS in high risk patients but was not significant in lower risk patients. The dose response was maintained across all risk groups. Medical comorbidities were balanced across all dose strata and sensitivity analysis demonstrated that other prognostic factors were unlikely to explain the observed dose response.

CONCLUSIONS

This study suggests that increasing dose significantly improves OS in prostate cancer patients treated with radiotherapy.

Contemporary role of androgen deprivation therapy for prostate cancer

CONTEXT

Androgen deprivation therapy (ADT) for prostate cancer (PCa) represents one of the most effective systemic palliative treatments known for solid tumors. Although clinical trials have assessed the role of ADT in patients with metastatic and advanced locoregional disease, the risk-benefit ratio, especially in earlier stages, remains poorly defined. Given the mounting evidence for potentially life-threatening adverse effects with short- and long-term ADT, it is important to redefine the role of ADT for this disease.

OBJECTIVE

Review the published experience with currently available ADT approaches in various contemporary clinical settings of PCa and reported serious treatment-related adverse events. This review addresses the level of evidence associated with the use of ADT in PCa, focusing upon survival outcome measures. Furthermore, this paper discusses evolving approaches targeting androgen receptor signaling pathways and emerging evidence from clinical trials with newer compounds.

EVIDENCE ACQUISITION

A comprehensive review of the literature was performed, focusing on data from the last 10 yr (January 2000 to July 2011) and using the terms androgen deprivation, hormone treatment, prostate cancer and adverse effects. Abstracts from trials reported at international conferences held in 2010 and 2011 were also evaluated.

EVIDENCE SYNTHESIS

Data from randomized controlled trials and population-based studies were analyzed in different clinical paradigms. Specifically, the role of ADT was evaluated in patients with nonmetastatic disease as the primary and sole treatment, in combination with radiation therapy (RT) or after surgery, and in patients with metastatic disease. The data suggest that in men with nonmetastatic disease, the use of primary ADT as monotherapy has not shown a benefit and is not recommended, while ADT combined with conventional-dose RT (<72Gy) for patients with high-risk disease may delay progression and prolong survival. The postoperative use of ADT remains poorly evaluated in prospective studies. Likewise, there are no trials evaluating the role of ADT in patients with biochemical relapses after surgery or RT. In patients with metastatic disease, there is a clear benefit in terms of quality of life, reduction of disease-associated morbidity, and possibly survival. Treatment with bilateral orchiectomy, luteinizing hormone-releasing hormone agonist therapy, with and without antiandrogens has been associated with various serious adverse events, including cardiovascular disease, diabetes, and skeletal complications that may also affect mortality.

CONCLUSIONS

Although ADT is an effective treatment of PCa, consistent long-term benefits in terms of quality and quantity of life are predominantly evident in patients with advanced/metastatic disease or when ADT is used in combination with RT (<72Gy) in patients with high-risk tumors. Implementation of ADT should be evidence based, with special consideration to adverse events and the risk-benefit ratio.

Controversies in the treatment of high-risk prostate cancer--what is the optimal combination of hormonal therapy and radiotherapy: a review of literature

BACKGROUND

In high-risk prostate carcinoma, there is controversy whether these patients should be treated with escalated-dose (> or =74 Gy) or conventional-dose radiotherapy (<74 Gy) combined with hormonal therapy. Furthermore, the issue of the optimal duration and timing of hormonal therapy are not well crystallized.

PATIENTS AND METHODS

A search for evidence from randomized- and large non-randomized studies in order to address these issues, was therefore initiated. For this purpose, MedLine, EMbase, and PubMed and the data base of the Dutch randomized dose-escalation trial, were consulted.

RESULTS AND CONCLUSIONS

From this search it was concluded that the benefit of hormonal therapy in combination with conventional-dose radiotherapy (<74 Gy) in high-risk prostate cancer is evident (Level 2 evidence); Levels 2 and 3 evidence were provided by several studies supporting the use of escalated-dose radiotherapy in high-risk prostate cancer. For the combination of hormonal therapy with escalated-dose radiotherapy in these patients, there is Level 2 evidence for moderately escalated dose (74 Gy) and high escalated dose (> or =78 Gy). The optimal duration and timing of hormonal therapy are not well defined. More randomized-controlled trials and meta-analyses are therefore needed to clearly determine the independent role of dose-escalation in high-risk patients treated with hormonal therapy and the optimal duration and timing of hormonal therapy.

Definitive radiotherapy for prostate cancer

The probability of extraprostatic disease may be estimated based on clinical T-stage, pretreatment prostatic-specific antigen, Gleason score, and percent positive core biopsies. Patients with disease confined to the prostate may be treated with either prostatectomy or radiotherapy (RT). Patients with extraprostatic disease without evidence of distant metastases are best managed with RT. RT consisting of either external beam and/or brachytherapy results in a relatively high likelihood of cure, particularly for those with low- and intermediate-risk disease. The impact of elective nodal RT on survival is unclear. Dose escalation results in improved biochemical relapse-free survival compared with standard dose RT. Androgen deprivation therapy likely improves the probability of disease control in patients with high-risk cancers.

Evidence-based radiation oncology: Definitive, adjuvant and salvage radiotherapy for non-metastatic prostate cancer

The standard treatment options based on the risk category (stage, Gleason score, PSA) for localized prostate cancer include surgery, radiotherapy and watchful waiting. The literature does not provide clear-cut evidence for the superiority of surgery over radiotherapy, whereas both approaches differ in their side effects. The definitive external beam irradiation is frequently employed in stage T1b-T1c, T2 and T3 tumors. There is a pretty strong evidence that intermediate- and high-risk patients benefit from dose escalation. The latter requires reduction of the irradiated normal tissue (using 3-dimensional conformal approach, intensity modulated radiotherapy, image-guided radiotherapy, etc.). Recent data suggest that prostate cancer may benefit from hypofractionation due to relatively low alpha/beta ratio; these findings warrant confirmation though. The role of whole pelvis irradiation is still controversial. Numerous randomized trials demonstrated a clinical benefit in terms of biochemical control, local and distant control, and overall survival from the addition of androgen suppression to external beam radiotherapy in intermediate- and high-risk patients. These studies typically included locally advanced (T3-T4) and poor-prognosis (Gleason score >7 and/or PSA >20 ng/mL) tumors and employed neoadjuvant/concomitant/adjuvant androgen suppression rather than only adjuvant setting. The ongoing trials will hopefully further define the role of endocrine treatment in more favorable risk patients and in the setting of the dose escalated radiotherapy. Brachytherapy (BRT) with permanent implants may be offered to low-risk patients (cT1-T2a, Gleason score <7, or 3+4, PSA <or=10 ng/mL), with prostate volume of <or=50 ml, no previous transurethral prostate resection and a good urinary function. Some recent data suggest a benefit from combining external beam irradiation and BRT for intermediate-risk patients. EBRT after radical prostatectomy improves disease-free survival and biochemical and local control rates in patients with positive surgical margins or pT3 tumors. Salvage radiotherapy may be considered at the time of biochemical failure in previously non-irradiated patients.

Radiation dose escalation combined with hormone therapy improves outcome in localised prostate cancer

We present the impact of systematic radiation dose escalation from 64 Gy to 66 Gy to 70 Gy on the outcome after radiation therapy (RT) alone or combined with hormonal treatment (HT) in a series of 494 consecutive localised prostate cancer patients treated during 1990-1999. Prognostic factors for prostate-specific antigen (PSA) failure, overall survival (OS) and prostate cancer specific survival (CSS) were investigated using multivariate analysis. T stage, pre-treatment PSA, grade, radiation dose and HT were found to be independent predictors of PSA failure. T stage, grade and HT were also independent predictors of both OS and CSS, while radiation dose was a significant predictor for OS and indicated a trend (p = 0.07) for CSS. A dose of 70 Gy combined with hormonal treatment improves PSA failure free survival and survival in localised prostate cancer compared with doses of 64-66 Gy.

Radiothérapie conformationnelle du cancer de la prostate : technique et résultats

A number of retrospective and prospective studies have demonstrated that radiotherapy of prostate cancer must be actually conformal. Three-dimensional (3D) treatment planning consists in an as accurate as possible definition of target-volume, usually by CT-scan, and design of radiation fields shaped to this target-volume. Several steps are required, each step being important for the overall quality of the treatment. Conformal radiotherapy is better tolerated than conventional irradiation, with significantly less rectal toxicity. It allows dose-escalation up to 80 Gy. It is now possible to go beyond this dose with intensity-modulated radiotherapy. The benefit of these high doses was demonstrated by some large retrospective studies and some prospective dose-escalation trials. Several randomized trials are in progress, preliminary results of two of them have been published, both showing an improvement in disease control with the higher doses. The advantage of higher doses is clearly evident for patients in the intermediate prognostic group, but is still discussed for patients with a low risk tumour or treated in combination with hormone therapy. Late proctitis is the main toxicity of these high doses. Some volume constraints have been defined during the last years and will allow a decrease of the rate of rectal toxicity. Because of these technological improvements, results of radiation therapy are now similar to those of surgery: no direct comparison with a randomized trial is available, but large comparative studies show that long-term disease control are identical with both techniques. Radiation therapy must be proposed to all patients with a prostate carcinoma as an alternative to surgery.

Radiotherapy in the Management of Clinically Localized Prostate Cancer: Evolving Standards, Consensus, Controversies and New Directions

Major advances have been made in the definitive use of various forms of radiotherapy (RT) in the management of clinically localized prostate cancer (PCa). Despite tremendous gains, the radiation oncology community continues to struggle with several key questions. In general, the areas of controversy pertain to how to improve the therapeutic ratio of RT. Specifically, key issues include dose escalation; the relative benefit of alternative forms of RT (ie, brachytherapy and protons); target localization; the use, timing, and duration of androgen deprivation; and the need for pelvic nodal irradiation. Multiple efforts have been made to address each of these issues; however, there is no consensus on how to resolve them. This review is an evidence-based critique of the available treatment approaches considered for the optimal use of radiotherapy as definitive management of clinically localized PCa.

70 Gy or more: which dose for which prostate cancer?

INTRODUCTION

Radical prostatectomy and radiotherapy are currently accepted treatment modalities for localized prostate cancer. Regarding radiotherapy, current evidence suggests that favorable treatment outcome critically depends on adequate radiation doses. However, the exact role of dose in relation to the individual risk profile is complex. In order to evaluate available data on radiation dose response relationships, in prostate cancer, a thorough and critical literature analysis was performed.

MATERIAL AND METHODS

Studies on dose response relationships from randomized trials, dose escalation trials, retrospective subgroup analyses and pooled data were identified by Pubmed and ISI web of sciences searches and were critically reviewed.

RESULTS AND CONCLUSION

All available data suggest a clear dose response relationship for radiotherapy for localized prostate cancer. In low risk cases, most studies suggest that doses of 70-72 Gy are adequate. Dose escalations up to 78-80 Gy seem to be beneficial for intermediate risk patients. Due to confounding variables, the dose response curves for high-risk patients are less steep. The integration of dose escalation into a more comprehensive treatment protocol is difficult, since trials on the relative impact of either hormonal ablation or inclusion of adjuvant nodal regions on dose escalation are missing.

Acute and late complications after radiotherapy for prostate cancer: results of a multicenter randomized trial comparing 68 Gy to 78 Gy

PURPOSE

To compare acute and late gastrointestinal (GI) and genitourinary (GU) side effects in prostate cancer patients randomized to receive 68 Gy or 78 Gy.

METHODS AND MATERIALS

Between June 1997 and February 2003, 669 prostate cancer patients were randomized between radiotherapy with a dose of 68 Gy and 78 Gy, in 2 Gy per fraction and using three-dimensional conformal radiotherapy. All T stages with prostate-specific antigen (PSA) <60 ng/mL were included, except any T1a and well-differentiated T1b-c tumors with PSA < or =4 ng/mL. Stratification was done for four dose-volume groups (according to the risk of seminal vesicles [SV] involvement), age, hormonal treatment (HT), and hospital. The clinical target volume (CTV) consisted of the prostate with or without the SV, depending on the estimated risk of SV invasion. The CTV-planning target volume (PTV) margin was 1 cm for the first 68 Gy and was reduced to 0.5 cm (0 cm toward the rectum) for the last 10 Gy in the 78 Gy arm. Four Dutch hospitals participated in this Phase III trial. Evaluation of acute and late toxicity was based on 658 and 643 patients, respectively. For acute toxicity (<120 days), the Radiation Therapy Oncology Group (RTOG) scoring system was used and the maximum score was reported. Late toxicity (>120 days) was scored according to the slightly adapted RTOG/European Organization for Research and Treatment of Cancer (EORTC) criteria.

RESULTS

The median follow-up time was 31 months. For acute toxicity no significant differences were seen between the two randomization arms. GI toxicity Grade 2 and 3 was reported as the maximum acute toxicity in 44% and 5% of the patients, respectively. For acute GU toxicity, these figures were 41% and 13%. No significant differences between both randomization arms were seen for late GI and GU toxicity, except for rectal bleeding requiring laser treatment or transfusion (p = 0.007) and nocturia (p = 0.05). The 3-year cumulative risk of late RTOG/EORTC GI toxicity grade > or =2 was 23.2% for 68 Gy, and 26.5% for 78 Gy (p = 0.3). The 3-year risks of late RTOG/EORTC GU toxicity grade > or =2 were 28.5% and 30.2% for 68 Gy and 78 Gy, respectively (p = 0.3). Factors related to acute GI toxicity were HT (p < 0.001), a higher dose-volume group (p = 0.01), and pretreatment GI symptoms (p = 0.04). For acute GU toxicity, prognostic factors were: pretreatment GU symptoms (p < 0.001), HT (p = 0.003), and prior transurethral resection of the prostate (TURP) (p = 0.02). A history of abdominal surgery (p < 0.001) and pretreatment GI symptoms (p = 0.001) were associated with a higher incidence of late GI grade > or =2 toxicity, whereas HT (p < 0.001), pretreatment GU symptoms (p < 0.001), and prior TURP (p = 0.006) were prognostic factors for late GU grade > or =2.

CONCLUSIONS

Raising the dose to the prostate from 68 Gy to 78 Gy resulted in higher incidences of acute and late GI and GU toxicity, but these differences were not significant, except for late rectal bleeding requiring treatment and late nocturia. Other factors than the studied dose levels appeared to be important in predicting toxicity after radiotherapy, especially previous surgical interventions (abdominal surgery or TURP), hormonal therapy, and the presence of pretreatment symptoms.

Is the alpha–beta ratio of prostate cancer really low? A prospective, non-randomized trial comparing standard and hyperfractionated conformal radiation therapy

BACKGROUND AND PURPOSE

The objectives of the current study were to compare genito-urinary (GU) and gastro-intestinal (GI) toxicities as well as biochemical control (bRFS) in prostate cancer, utilizing conventional (2.0 Gy daily) (STD) or hyperfractionated (HFX) conformal irradiation (CRT). HFX (1.2 Gy BID) was chosen as a radiobiological method to try to reduce long term sequelae without compromising local control.

PATIENTS AND METHODS

Three-hundred-and-seventy consecutive patients (pts) entered this prospective, non-randomized trial in the period January 1993-January 2003; 209 were treated with STD and 161 with HFX CRT. All were evaluable for acute toxicity analysis, 179 (STD) and 151 pts (HFX) being evaluable for late sequelae and bRFS analyses. Pt characteristics were not statistically different in the two groups. CRT consisted of a 4-field technique for prostate and/or pelvic nodes and a 5-field boost with rectal shielding. Median doses were 74 and 79.2 Gy for STD and HFX patients respectively, the latter dose being isoeffective for tumour control assuming alpha/beta=10 (EQD(2)=73.9 Gy). Median follow-up was 29.4 months (25.2 mos for STD; 37.7 mos for HFX; P<0.01). The two regimens were compared in terms of acute and late GU and GI toxicities and 5-year bRFS by univariate and multivariate analyses.

RESULTS

Acute grade> or =2 GU toxicity was higher in the STD group (48.6% versus 37.3% in HFX, P=0.03), while no significant difference was found for acute GI toxicity. Late grade> or =2 GU and GI toxicities were lower in the HFX group (5-year actuarial rate: GU: 10.1% versus 20.3%, P=0.05; GI: 6.0% versus 10.6%, P=0.18). Five-year bRFS were 70% (+/-13.8%, 95% CI) and 82.6% (+/-7.2%) for STD and HFX, respectively (P=0.44); a trend favouring HFX was found in the subgroup of pts who did not receive hormonal therapy (5-year bRFS: 85.9%+/-12.4% versus 63.9%+/-23.8%, P=0.15). Multivariate analysis revealed only risk groups and age statistically related to bRFS but not fractionation regimen. Using the Nahum-Chapman TLCP model and prostate parameter set, which includes hypoxia, the TLCPs are approximately equal for the two regimens, whereas assuming alpha/beta=1.5 and no hypoxia we obtain 73% for the STD group but only 36% for the HFX group.

CONCLUSIONS

As expected from radiobiological considerations, HFX reduces GI and GU late toxicities. Concerning early bRFS, our clinical findings suggest that HFX is no less effective than STD when delivering an isoeffective (alpha/beta=10) dose. Despite the relatively short follow-up, this result appears to be inconsistent with a low alpha/beta ratio for prostate cancer.

MRI-guided HDR prostate brachytherapy in standard 1.5T scanner

PURPOSE

Magnetic resonance imaging (MRI) provides superior visualization of the prostate and surrounding anatomy, making it the modality of choice for imaging the prostate gland. This pilot study was performed to determine the feasibility and dosimetric quality achieved when placing high-dose-rate prostate brachytherapy catheters under MRI guidance in a standard "closed-bore" 1.5T scanner.

METHODS AND MATERIALS

Patients with intermediate-risk and high-risk localized prostate cancer received MRI-guided high-dose-rate brachytherapy boosts before and after a course of external beam radiotherapy. Using a custom visualization and targeting program, the brachytherapy catheters were placed and adjusted under MRI guidance until satisfactory implant geometry was achieved. Inverse treatment planning was performed using high-resolution T(2)-weighted MRI.

RESULTS

Ten brachytherapy procedures were performed on 5 patients. The median percentage of volume receiving 100% of prescribed minimal peripheral dose (V(100)) achieved was 94% (mean, 92%; 95% confidence interval, 89-95%). The urethral V(125) ranged from 0% to 18% (median, 5%), and the rectal V(75) ranged from 0% to 3.1% (median, 0.3%). In all cases, lesions highly suspicious for malignancy could be visualized on the procedural MRI, and extracapsular disease was identified in 2 patients.

CONCLUSION

High-dose-rate prostate brachytherapy in a standard 1.5T MRI scanner is feasible and achieves favorable dosimetry within a reasonable period with high-quality image guidance. Although the procedure was well tolerated in the acute setting, additional follow-up is required to determine the long-term safety and efficacy of this approach.