Postprostatectomy radiation therapy: an evidence-based review

A four-gene transcript score to predict metastatic-lethal progression in men treated for localized prostate cancer: Development and validation studies

BACKGROUND

Molecular studies have tried to address the unmet need for prognostic biomarkers in prostate cancer (PCa). Some gene expression tests improve upon clinical factors for prediction of outcomes, but additional tools for accurate prediction of tumor aggressiveness are needed.

METHODS

Based on a previously published panel of 23 gene transcripts that distinguished patients with metastatic progression, we constructed a prediction model using independent training and testing datasets. Using the validated messenger RNAs and Gleason score (GS), we performed model selection in the training set to define a final locked model to classify patients who developed metastatic-lethal events from those who remained recurrence-free. In an independent testing dataset, we compared our locked model to established clinical prognostic factors and utilized Kaplan-Meier curves and receiver operating characteristic analyses to evaluate the model's performance.

RESULTS

Thirteen of 23 previously identified gene transcripts that stratified patients with aggressive PCa were validated in the training dataset. These biomarkers plus GS were used to develop a four-gene (CST2, FBLN1, TNFRSF19, and ZNF704) transcript (4GT) score that was significantly higher in patients who progressed to metastatic-lethal events compared to those without recurrence in the testing dataset (P = 5.7 × 10^-11 ). The 4GT score provided higher prediction accuracy (area under the ROC curve [AUC] = 0.76; 95% confidence interval [CI] = 0.69-0.83; partial area under the ROC curve [pAUC] = 0.008) than GS alone (AUC = 0.63; 95% CI = 0.56-0.70; pAUC = 0.002), and it improved risk stratification in subgroups defined by a combination of clinicopathological features (ie, Cancer of the Prostate Risk Assessment-Surgery).

CONCLUSION

Our validated 4GT score has prognostic value for metastatic-lethal progression in men treated for localized PCa and warrants further evaluation for its clinical utility.

Radiotherapy after prostatectomy: prognosis, timing and outcomes

Biochemical disease-free survival following radical prostatectomy can be improved with the use of adjuvant and salvage radiotherapy. However, there is a lack of consensus over the ideal timing to start adjuvant and salvage radiotherapy after surgery. The literature in relation to adjuvant and salvage radiotherapy following radical prostatectomy was reviewed, focusing specifically on the prognostic factors that influence the need for postoperative radiotherapy, outcomes following adjuvant and salvage radiotherapy and potential side effects. Post-surgery prognostic factors can be useful in identifying patients early on who may benefit from adjuvant radiotherapy. While there is literature examining the role of radiotherapy following radical prostatectomy, few dedicated trials investigate this area thoroughly.

Roles of Distal and Genic Methylation in the Development of Prostate Tumorigenesis Revealed by Genome-wide DNA Methylation Analysis

Aberrant DNA methylation at promoters is often linked to tumorigenesis. But many aspects of DNA methylation remain unexplored, including the individual roles of distal and gene body methylation, as well as their collaborative roles with promoter methylation. Here we performed a MBD-seq analysis on prostate specimens classified into low, high, and very high risk group based on Gleason score and TNM stages. We identified gene sets with differential methylation regions (DMRs) in Distal, TSS, gene body and TES. To understand the collaborative roles, TSS was compared with the other three DMRs, resulted in 12 groups of genes with collaborative differential methylation patterns (CDMPs). We found several groups of genes that show opposite methylation patterns in Distal and Genic regions compared to TSS region, and in general they are differentially expressed genes (DEGs) in tumors in TCGA RNA-seq data. IPA (Ingenuity Pathway Analysis) reveals AR/TP53 signaling network to be a major signaling pathway, and survival analysis indicates genes subsets significantly associated with prostate cancer recurrence. Our results suggest that DNA methylation in Distal and Genic regions also plays critical roles in contributing to prostate tumorigenesis, and may act either positively or negatively with TSSs to alter gene regulation in tumors.

Evaluating the clinical impact of a genomic classifier in prostate cancer using individualized decision analysis

BACKGROUND

Currently there is controversy surrounding the optimal way to treat patients with prostate cancer in the post-prostatectomy setting. Adjuvant therapies carry possible benefits of improved curative results, but there is uncertainty in which patients should receive adjuvant therapy. There are concerns about giving toxicity to a whole population for the benefit of only a subset. We hypothesized that making post-prostatectomy treatment decisions using genomics-based risk prediction estimates would improve cancer and quality of life outcomes.

METHODS

We developed a state-transition model to simulate outcomes over a 10 year horizon for a cohort of post-prostatectomy patients. Outcomes included cancer progression rates at 5 and 10 years, overall survival, and quality-adjusted survival with reductions for treatment, side effects, and cancer stage. We compared outcomes using population-level versus individual-level risk of cancer progression, and for genomics-based care versus usual care treatment recommendations.

RESULTS

Cancer progression outcomes, expected life-years (LYs), and expected quality-adjusted life-years (QALYs) were significantly different when individual genomics-based cancer progression risk estimates were used in place of population-level risk estimates. Use of the genomic classifier to guide treatment decisions provided small, but statistically significant, improvements in model outcomes. We observed an additional 0.03 LYs and 0.07 QALYs, a 12% relative increase in the 5-year recurrence-free survival probability, and a 4% relative reduction in the 5-year probability of metastatic disease or death.

CONCLUSIONS

The use of genomics-based risk prediction to guide treatment decisions may improve outcomes for prostate cancer patients. This study offers a framework for individualized decision analysis, and can be extended to incorporate a wide range of personal attributes to enable delivery of patient-centered tools for informed decision-making.

Golgi phosphoprotein 3 expression predicts poor prognosis in patients with prostate cancer undergoing radical prostatectomy

Golgi phosphoprotein 3 (GOLPH3) has recently been implicated as an oncogene involved in the development of carcinoma in a number of organs. The expression of GOLPH3 in prostate cancer (PCa) tissues was investigated in the present study. Human PC-3 and LNCaP PCa cell lines were analyzed in order to assess whether silencing of GOLPH3 expression affects cell vitality, migration and invasion, in vitro. An immunohistochemistry analysis was performed in order to measure the expression of GOLPH3 in samples from 117 patients with PCa and from 50 patients with benign prostatic hyperplasia (BPH). Associations between GOLPH3 expression and clinicopathological parameters, such as overall survival, were assessed. GOLPH3 expression was shown to be significantly greater in PCa tissues than in BPH tissues. GOLPH3 expression was positively correlated with Gleason score (P=0.031), tumor stage (T stage; P=0.020) and lymph node status (P=0.013), in patients with PCa. Biochemical recurrence-free survival (serum prostate-specific antigen-based) and overall survival, were reduced in patients with GOLPH3-positive PCa. A multivariate analysis indicated that GOLPH3 expression was an independent predictor of biochemical recurrence-free survival [hazard ratio (HR), 2.943; 95% confidence interval (CI), 1.190-5.521; P=0.028], and of overall survival (HR, 4.371; 95% CI, 2.045-7.109; P=0.014). Transfection with GOLPH3‑targeted small interfering RNA reduced the capability of PC-3 and LNCaP cell lines to proliferate, migrate and invade in vitro, compared with the controls. The level of GOLPH3 expression in radical prostatectomy samples may be useful for predicting biochemical recurrence-free survival and overall survival in patients with PCa.

Radiation therapy after radical prostatectomy for prostate cancer: evaluation of complications and influence of radiation timing on outcomes in a large, population-based cohort

Purpose

To evaluate the influence of timing of salvage and adjuvant radiation therapy on outcomes after prostatectomy for prostate cancer.

Methods

Using the Surveillance, Epidemiology, and End Results-Medicare linked database, we identified prostate cancer patients diagnosed during 1995–2007 who had one or more adverse pathological features after prostatectomy. The final cohort of 6,137 eligible patients included men who received prostatectomy alone (n = 4,509) or with adjuvant (n = 894) or salvage (n = 734) radiation therapy. Primary outcomes were genitourinary, gastrointestinal, and erectile dysfunction events and survival after treatment(s).

Results

Radiation therapy after prostatectomy was associated with higher rates of gastrointestinal and genitourinary events, but not erectile dysfunction. In adjusted models, earlier treatment with adjuvant radiation therapy was not associated with increased rates of genitourinary or erectile dysfunction events compared to delayed salvage radiation therapy. Early adjuvant radiation therapy was associated with lower rates of gastrointestinal events that salvage radiation therapy, with hazard ratios of 0.80 (95% CI, 0.67–0.95) for procedure-defined and 0.70 (95% CI, 0.59, 0.83) for diagnosis-defined events. There was no significant difference between ART and non-ART groups (SRT or RP alone) for overall survival (HR = 1.13 95% CI = (0.96, 1.34) p = 0.148).

Conclusions

Radiation therapy after prostatectomy is associated with increased rates of gastrointestinal and genitourinary events. However, earlier radiation therapy is not associated with higher rates of gastrointestinal, genitourinary or sexual events. These findings oppose the conventional belief that delaying radiation therapy reduces the risk of radiation-related complications.

Radiotherapy in the management of prostate cancer after radical prostatectomy

The choice of treatment options for prostate cancer patients who have undergone radical prostatectomy depends on their risk profile, which is determined by the tumor node metastasis (TNM) status, histopathologic findings, and the pre- and post-radical prostatectomy PSA characteristics. The results of large clinical studies with a 10-year follow-up or more are the backbone of predictive models for risk estimates that incorporate these criteria and also for guideline recommendations. For low-to-intermediate-risk prostate cancer patients and older patients, observation with--in case of biochemical recurrence--early salvage radiotherapy can be advised after R0 resection, thus, avoiding overtreatment. After R1 resection, adjuvant radiotherapy should be considered. Patients with two or more positive lymph nodes and/or with distant metastasis may benefit from adjuvant hormone deprivation therapy. Beyond this rough outline, detailed analysis of subgroups is still required (and ongoing) to enable individually optimized treatment.

Pushing the limits of radiation therapy for prostate cancer: where do we go next?

There have been significant advancements in the quality and precision of radiation therapy (RT) for prostate cancer over the past two decades. The development and implementation of intensity-modulated radiation therapy has allowed for RT dose-escalation without parallel increases in treatment morbidity. Moreover, integration of androgen deprivation therapy with definitive RT has led to improvements in outcomes for certain subgroups of prostate cancer patients. In this review, we highlight several ongoing and developing technical advances that hold promise for further optimizing RT care, including proton beam therapy, inter- and intra-fractional image-guided dose-delivery, methods for improved target volume definition, and development of techniques for safely performing hypofractionation and stereotactic body radiotherapy. We also discuss the importance of investigating the potential benefit of integrating novel systemic therapies with prostate RT to further improve outcomes for patients with locally advanced prostate cancer.

Discovery and validation of a prostate cancer genomic classifier that predicts early metastasis following radical prostatectomy

PURPOSE

Clinicopathologic features and biochemical recurrence are sensitive, but not specific, predictors of metastatic disease and lethal prostate cancer. We hypothesize that a genomic expression signature detected in the primary tumor represents true biological potential of aggressive disease and provides improved prediction of early prostate cancer metastasis.

METHODS

A nested case-control design was used to select 639 patients from the Mayo Clinic tumor registry who underwent radical prostatectomy between 1987 and 2001. A genomic classifier (GC) was developed by modeling differential RNA expression using 1.4 million feature high-density expression arrays of men enriched for rising PSA after prostatectomy, including 213 who experienced early clinical metastasis after biochemical recurrence. A training set was used to develop a random forest classifier of 22 markers to predict for cases--men with early clinical metastasis after rising PSA. Performance of GC was compared to prognostic factors such as Gleason score and previous gene expression signatures in a withheld validation set.

RESULTS

Expression profiles were generated from 545 unique patient samples, with median follow-up of 16.9 years. GC achieved an area under the receiver operating characteristic curve of 0.75 (0.67-0.83) in validation, outperforming clinical variables and gene signatures. GC was the only significant prognostic factor in multivariable analyses. Within Gleason score groups, cases with high GC scores experienced earlier death from prostate cancer and reduced overall survival. The markers in the classifier were found to be associated with a number of key biological processes in prostate cancer metastatic disease progression.

CONCLUSION

A genomic classifier was developed and validated in a large patient cohort enriched with prostate cancer metastasis patients and a rising PSA that went on to experience metastatic disease. This early metastasis prediction model based on genomic expression in the primary tumor may be useful for identification of aggressive prostate cancer.