In Patients Experiencing Biochemical Failure After Radiotherapy, Pretreatment Risk Group and PSA Velocity Predict Differences in Overall Survival and Biochemical Failure-Free Interval

Effects of Androgen Deprivation Therapy on Prostate Cancer Outcomes According to Competing Event Risk: Secondary Analysis of a Phase 3 Randomised Trial

BACKGROUND

Previous studies indicate that the benefit of short-term androgen deprivation therapy (ADT) with radiotherapy (RT) for prostate cancer depends on competing risks.

OBJECTIVE

To determine whether a quantitative method to stratify patients by risk for competing events (omega score) could identify subgroups that selectively benefit from ADT.

DESIGN, SETTING, AND PARTICIPANTS

An ancillary analysis of NRG/RTOG 9408 phase 3 trial (NCT00002597) involving 1945 prostate cancer patients was conducted.

INTERVENTION

Short-term ADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We applied generalised competing event regression models incorporating age, performance status, comorbidity, T category, Gleason score (GS), and prostate-specific antigen (PSA), to stratify patients according to relative hazards for primary cancer-related events (distant metastasis or prostate cancer death) versus competing noncancer mortality. We tested interactions between ADT and subgroups defined by standard risk criteria versus relative risk (RR) using the omega score.

RESULTS AND LIMITATIONS

T2b, higher GS, and higher PSA were associated with an increased RR for cancer-related versus competing mortality events (a higher omega score); increased age and comorbidity were associated with a decreased omega score. Of 996 patients with low-risk/favourable intermediate-risk (FIR) disease, 286 (28.7%) had a high omega score (≥0.314). Of 768 patients with unfavourable intermediate-risk disease, 175 (22.8%) had a low omega score. The overall discordance in risk classification was 26.1%. Both standard criteria and omega score identified significant interactions for the effect of ADT on cancer-related events and late mortality in low- versus high-risk subgroups. Within the low-risk/FIR subgroup, a higher omega score identified patients in whom ADT significantly reduced cancer events and improved event-free survival. Limitations are the need for external/prospective validation and lower RT doses than contemporary standards.

CONCLUSIONS

Stratification based on competing event risk is useful for identifying prostate cancer patients who selectively benefit from ADT.

PATIENT SUMMARY

We analysed the effectiveness of androgen deprivation therapy (ADT) for localised prostate cancer among patients, defined by the relative risk (RR) for cancer versus noncancer events. Among patients with traditional low-risk/favourable intermediate-risk disease, those with a higher RR benefitted from short-term ADT.

Significance of prostate-specific antigen kinetics after three-dimensional conformal radiotherapy with androgen deprivation therapy in patients with localized prostate cancer

BACKGROUND

To evaluate the relationship between biochemical recurrence and post-radiation prostate-specific antigen (PSA) kinetics in patients with localized prostate cancer treated by radiotherapy with various durations of androgen deprivation therapy (ADT).

METHODS

We reviewed our single-institution, retrospectively maintained data of 144 patients with T1c-T3N0M0 prostate cancer who underwent three-dimensional conformal radiotherapy (3D-CRT) between December 2005 and December 2015 and 113 patients were fulfilled the inclusion criteria. In this cohort, 3D-CRT was delivered with a dose in the range from 70.0 to 72.0 Gy with ADT. All patients received ADT as concurrent regimens. Biochemical recurrence was defined on the basis of the following: "PSA nadir + 2.0 ng/ml or the clinical judgement of attending physicians". Kaplan-Meier, log-rank, and Cox regression analyses were carried out.

RESULTS

The median follow-up period was 54.0 months. The median duration of ADT was 17 months (interquartile range, 10-24 months). There was a trend toward statistical significant correlation between post-radiation PSA decline rate of ≥ 90% and PSA recurrence (p = 0.056). The same correlation could be observed in D'Amico high-risk patients (p = 0.036). However, it was not observed between PSA nadir and PSA recurrence (p = 0.40) in univariate analysis. Furthermore, multivariate analysis showed that post-radiation PSA decline rate of ≥ 90% was a significant predictor of biochemical recurrence in patients who received radiotherapy with various durations of ADT (p = 0.044).

CONCLUSIONS

Post-radiation PSA decline rate of ≥ 90% was a prognostic factor for biochemical recurrence in localized prostate cancer patients received 3D-CRT with various durations of ADT.

Prognostic Factors for Prostate Cancer Endpoints Following Biochemical Failure: A Review of the Literature

PURPOSE

In the setting of biochemical failure (BCF) following primary treatment for prostate cancer, additional discrimination between clinically significant and non-clinically significant biochemical recurrence is critical in defining robust surrogate endpoints for prostate cancer and guiding salvage management decisions. We reviewed the literature to determine which prognostic factors are most significant for predicting prostate cancer-specific survival (PCSS), metastases-free survival (MFS), and/or overall survival (OS) after BCF.

MATERIALS AND METHODS

A search of PubMed from 1980 to 2013 yielded 999 studies that examined prognostic factors predictive for PCSS, MFS, and/or OS in prostate cancer patients with BCF following primary treatment. Eligibility criteria for inclusion were: 1) examined a prostate cancer population in the setting of BCF without overt clinical relapse following primary treatment with radical prostatectomy or radiotherapy; 2) based analyses on patient parameters obtained prior to the initiation of salvage therapies; and 3) determined clinical prognostic factors that were significant prognostic measures for at least one of three clinically relevant endpoints: OS, PCS, or MFS.

RESULTS

Nineteen eligible studies reported on 8,040 patients that experienced BCF from 1981-2013. The initial primary therapy was variable: radical prostatectomy alone (n=8), radiotherapy alone (n=4), radiotherapy/radical prostatectomy ± adjuvant therapy (n=5), and multiple treatment arms (n=2). There was also heterogeneity in which outcomes were assessed: PCSS (n=14), MFS (n=7), and OS (n=5). The prognostic factors most commonly found to be significant on multivariate analyses were PSA doubling time (PSADT), time to biochemical failure (TTBF), pathological Gleason score (pGS), and age.  

CONCLUSIONS

Risk stratification in prostate cancer post-BCF is challenging because of limited predictive modeling that can determine which patients will optimally benefit from salvage therapy. Our systematic literature review has identified PSADT, TTBF, pGS, and age as the leading prognostic factors for the prediction of PCSS, MFS, and OS after BCF. We plan to leverage the Canadian ProCaRS database to perform predictive modeling using the putative findings in the present study in order to propose potential evidence-based surrogate endpoints for prostate cancer in the setting of BCF.

Contemporary issues in radiotherapy for clinically localized prostate cancer

Radiotherapy is a valid curative alternative to surgery for prostate cancer. However, patient selection is critical to ensure patients obtain benefits from therapy delivered with curative intent. Dose-escalated radiation has been shown to improve patient outcomes, facilitated by development of robust image guidance and better target delineation imaging technologies. These concepts have also rekindled interest in hypofractionated radiotherapy in the forms of stereotactic body radiotherapy and brachytherapy. Postprostatectomy radiotherapy also improves long-term biochemical outcome in men at high risk of local recurrence.

PSA nadir of <0.5 ng/mL following brachytherapy for early-stage prostate adenocarcinoma is associated with freedom from prostate-specific antigen failure

PURPOSE

Because limited information exists regarding whether the rate or magnitude of PSA decline following brachytherapy predicts long-term clinical outcomes, we evaluated whether achieving a prostate-specific antigen (PSA) nadir (nPSA) <0.5 ng/mL following brachytherapy is associated with decreased PSA failure and/or distant metastasis.

METHODS AND MATERIALS

We retrospectively analyzed our database of early-stage prostate adenocarcinoma patients who underwent brachytherapy, excluding those receiving androgen-deprivation therapy and those with <2 years follow-up. Median and mean pretreatment PSA were 6 ng/mL and 7.16 ng/mL, respectively. By clinical stage, 775 were low risk (≤ T2a), 126 were intermediate risk (T2b), and 20 were high risk (>T2b). By Gleason score, 840 were low risk (≤ 6), 71 were intermediate risk (7), and 10 were high risk (>7). Patients were treated with brachytherapy only (I-125, n = 779, or Pd-103, n = 47), or brachytherapy + external-beam radiation therapy (n = 95). Median follow-up was 6.3 years. We noted whether nPSA <0.5 ng/mL was achieved and the time to achieve this nadir and tested for associations with pretreatment risk factors. We also determined whether this PSA endpoint was associated with decreased PSA failure or distant metastasis.

RESULTS

Absence of high-risk factors in clinical stage (≤ T2b), Gleason score (≤ 7), and pretreatment PSA (≤ 20 ng/mL) was significantly associated with achieving nPSA <0.5 ng/mL. By Kaplan-Meier analysis, patients achieving nPSA <0.5 ng/mL had significantly higher long-term freedom from biochemical failure (FFBF) than nonresponders (5-year FFBF: 95.2 ± 0.8% vs. 71.5 ± 6.7%; p < 0.0005). Among responders, those who achieved nPSA <0.5 ng/mL in ≤ 5 years had higher FFBF than those requiring >5 years (5-year FFBF: 96.7 ± 0.7% vs. 80.8 ± 4.6%; p < 0.0005). On multivariate analysis, patients who achieved nPSA <0.5 ng/mL in ≤ 5 years had significantly higher FFBF than other patients.

CONCLUSIONS

Pretreatment risk factors (clinical tumor stage, Gleason score, pretreatment PSA) strongly predict for patients achieving nPSA <0.5 ng/mL following brachytherapy, and this cohort had significantly higher long-term FFBF.

An update on the changing indications for androgen deprivation therapy for prostate cancer

Quality of life has become increasingly more important for men diagnosed with prostate cancer. In light of this and the recognized risks of androgen deprivation therapy (ADT), the guidelines and use of ADT have changed significantly over the last few years. This paper reviews the current recommendations and the future perspectives regarding ADT. The benefits of ADT are evident neoadjuvantly and adjuvantly in patients treated with external beam radiation therapy for intermediate- and high-risk disease, in patients who have undergone prostatectomy with lymph node involvement, in high-risk patients after definitive therapy, and in patients who have developed progression or metastasis. Finally, this paper reviews the risks and benefits of each of these scenarios and the risks of androgen deprivation in general, and it delineates the areas where ADT was previously recommended, but where evidence is lacking for its additional benefit.

DNA vaccination with electroporation induces increased antibody responses in patients with prostate cancer

We are evaluating the use of electroporation (EP) to deliver a novel DNA vaccine, p.DOM-PSMA(27). This vaccine encodes a domain (DOM) of fragment C of tetanus toxin to induce CD4(+) T cell help, fused to a tumor-derived epitope from prostate-specific membrane antigen (PSMA) for use in HLA-A2(+) patients with recurrent prostate cancer. We report on safety and tolerability and on antibody response to DOM as a first indication of the effect of EP in patients. In this open label phase I/II, two-arm, dose escalation trial DNA was delivered either by intramuscular injection or by intramuscular injection followed by EP (DNA+EP), with five patients per dose level. Three vaccinations were given at 0, 4, and 8 weeks,with booster doses at 24 and 48 weeks; here we allowed crossover between study arms if supported by the safety and immunological data. In the 20 patients in the first two dose cohorts we observed that beyond brief and acceptable pain at the injection site, EP did not appear to add toxicity to the vaccination. We evaluated humoral responses to DOM. Low anti-DOM IgG antibody responses were observed after intramuscular injection of DNA without EP (at week 12: mean 1.7- vs. 24.5-fold increase over baseline with DNA+EP). These could be boosted by delivery of DNA+EP at later time points. Delivery of DNA+EP at all five vaccinations yielded the highest levels of anti-DOM antibody. Responses persisted to 18 months of follow-up. These data establish EP as a potent method for stimulating humoral responses induced by DNA vaccination in humans.

Update on the management of prostate cancer with goserelin acetate: patient perspectives

The guidelines for the use of androgen deprivation therapy (ADT) have changed significantly over the last 5 years. This paper reviews the current recommendations and documents the reasons for these changes, in a review of the world's literature on ADT over the last 5 years. Special emphasis on randomized controlled trials and high-impact journals was included in the Medline search and review. One hundred articles on this topic written in the last 5 years were reviewed. Fifty-nine contained nonindustry-biased findings in major-impact journals and were available in English. The benefits of ADT are evident in several areas, including neoadjuvantly and adjuvantly in patients treated with external beam radiation therapy for intermediate- and high-risk disease; in patients who have undergone prostatectomy and who are found to have lymph node involvement on surgical resection; in high-risk patients after definitive therapy; and in patients who have developed symptomatic local progression or metastasis. This paper reviews the risks and benefits in each of these scenarios and the risks of androgen deprivation in general, and delineates the areas where ADT was previously recommended, but has been found to no longer be of benefit.