The Prostate Testing for Cancer and Treatment (ProtecT) study: what have we learnt?

The Clinical Significance of Maximum Tumor Diameter on MRI in Men Undergoing Radical Prostatectomy or Definitive Radiotherapy for Locoregional Prostate Cancer

INTRODUCTION

Maximum tumor diameter (MTD) on pretreatment magnetic resonance imaging (MRI) has the potential to further risk stratify for men with prostate cancer (PCa) prior to definitive local therapy. We aim to evaluate the prognostic impact of radiographic maximum tumor diameter (MTD) in men with localized prostate cancer.

PATIENTS AND METHODS

From a single-center retrospective cohort of men receiving definitive treatment for PCa (radical prostatectomy [RP] or radiotherapy [RT]) with available pretreatment MRI, we conducted univariable and multivariable Cox proportional-hazards models for progression using clinical variables including age, NCCN risk group, radiographic extracapsular extension (ECE), radiographic seminal vesical invasion (SVI), and MTD. RP and RT cohorts were analyzed separately. Covariates were used in a classification and regression tree (CART) analysis and progression-free survival was estimated with the Kaplan-Meier method and groups were compared using log-rank tests.

RESULTS

The cohort included 631 patients (n = 428 RP, n = 203 RT). CART analysis identified 4 prognostic groups for patients treated with RP and 2 prognostic groups in those treated with RT. In the RP cohort, NCCN low/intermediate risk group patients with MTD>=15 mm had significantly worse PFS than those with MTD <= 14 mm, and NCCN high-risk patients with radiographic ECE had significantly worse PFS than those without ECE. In the RT cohort, PFS was significantly worse in the cohort with MTD >= 23 mm than those <= 22 mm.

CONCLUSION

Radiographic MTD may be a useful prognostic factor for patients with locoregional prostate cancer. This is the first study to illustrate that the importance of pretreatment tumor size may vary based on treatment modality.

Placebo comparator group selection and use in surgical trials: the ASPIRE project including expert workshop

BACKGROUND

The use of placebo comparisons for randomised trials assessing the efficacy of surgical interventions is increasingly being considered. However, a placebo control is a complex type of comparison group in the surgical setting and, although powerful, presents many challenges.

OBJECTIVES

To provide a summary of knowledge on placebo controls in surgical trials and to summarise any recommendations for designers, evaluators and funders of placebo-controlled surgical trials.

DESIGN

To carry out a state-of-the-art workshop and produce a corresponding report involving key stakeholders throughout.

SETTING

A workshop to discuss and summarise the existing knowledge and to develop the new guidelines.

RESULTS

To assess what a placebo control entails and to assess the understanding of this tool in the context of surgery is considered, along with when placebo controls in surgery are acceptable (and when they are desirable). We have considered ethics arguments and regulatory requirements, how a placebo control should be designed, how to identify and mitigate risk for participants in these trials, and how such trials should be carried out and interpreted. The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Surgical placebos might be most appropriate when there is poor evidence for the efficacy of the procedure and a justified concern that results of a trial would be associated with a high risk of bias, particularly because of the placebo effect.

CONCLUSIONS

The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Feasibility work is recommended to optimise the design and implementation of randomised controlled trials. An outline for best practice was produced in the form of the Applying Surgical Placebo in Randomised Evaluations (ASPIRE) guidelines for those considering the use of a placebo control in a surgical randomised controlled trial.

LIMITATIONS

Although the workshop participants involved international members, the majority of participants were from the UK. Therefore, although every attempt was made to make the recommendations applicable to all health systems, the guidelines may, unconsciously, be particularly applicable to clinical practice in the UK NHS.

FUTURE WORK

Future work should evaluate the use of the ASPIRE guidelines in making decisions about the use of a placebo-controlled surgical trial. In addition, further work is required on the appropriate nomenclature to adopt in this space.

FUNDING

Funded by the Medical Research Council UK and the National Institute for Health Research as part of the Medical Research Council-National Institute for Health Research Methodology Research programme.

Circulating Metabolic Biomarkers of Screen-Detected Prostate Cancer in the ProtecT Study

BACKGROUND

Whether associations between circulating metabolites and prostate cancer are causal is unknown. We report on the largest study of metabolites and prostate cancer (2,291 cases and 2,661 controls) and appraise causality for a subset of the prostate cancer-metabolite associations using two-sample Mendelian randomization (MR).

METHODS

The case-control portion of the study was conducted in nine UK centers with men ages 50-69 years who underwent prostate-specific antigen screening for prostate cancer within the Prostate Testing for Cancer and Treatment (ProtecT) trial. Two data sources were used to appraise causality: a genome-wide association study (GWAS) of metabolites in 24,925 participants and a GWAS of prostate cancer in 44,825 cases and 27,904 controls within the Association Group to Investigate Cancer Associated Alterations in the Genome (PRACTICAL) consortium.

RESULTS

Thirty-five metabolites were strongly associated with prostate cancer (P < 0.0014, multiple-testing threshold). These fell into four classes: (i) lipids and lipoprotein subclass characteristics (total cholesterol and ratios, cholesterol esters and ratios, free cholesterol and ratios, phospholipids and ratios, and triglyceride ratios); (ii) fatty acids and ratios; (iii) amino acids; (iv) and fluid balance. Fourteen top metabolites were proxied by genetic variables, but MR indicated these were not causal.

CONCLUSIONS

We identified 35 circulating metabolites associated with prostate cancer presence, but found no evidence of causality for those 14 testable with MR. Thus, the 14 MR-tested metabolites are unlikely to be mechanistically important in prostate cancer risk.

IMPACT

The metabolome provides a promising set of biomarkers that may aid prostate cancer classification.

National trends in management of localized prostate cancer: A population based analysis 2004-2013

PURPOSE

Recent years have brought many changes in the management of localized prostate cancer as national screening guidelines have been updated and diagnostic practice patterns evolved. We sought to better understand how the changing landscape influenced treatment utilization in the United States.

METHODS

We used the SEER database in this retrospective analysis of patients with clinically localized prostate cancer between 2004 and 2013. We evaluated utilization of primary treatment modalities over time with descriptive and trend analyses, and examined treatment utilization by cancer risk group and age at diagnosis.

RESULTS

Of 398 074 patients in the analytic data set, 38% elected radiation therapy, 38% underwent radical prostatectomy, and 24% opted for expectant management. While in 2004 radiation treatment was almost twice as common as expectant management (42% vs 23%), by 2013 approximately equal percentages of patients were treated with each of the three modalities. Expectant management use increased over time, while the proportion of patients opting for surgery decreased remarkably with increasing age at diagnosis in intermediate- and higher-risk disease. Among radiotherapy options, brachytherapy was most common among lower-risk patients in 2004 but substantially decreased over time (P < 0.001).

CONCLUSIONS

Management of localized prostate cancer changed substantially over time in the United States. Utilization of expectant management has increased for men with low- and intermediate risk cancer. Among those who pursue curative therapy, younger men remain more likely to elect surgery whereas older men tend to choose radiotherapy. Further studies are needed to better characterize factors contributing to treatment selection.

Introducing new technology safely into urological practice

PURPOSE

Surgical innovation is necessary to ensure continued improvement in patient care. However, several challenges unique to the surgical craft are encountered during the development and validation of such new technology. This article highlights some of these challenges and gives an overview of existing solutions.

METHODS

A Pubmed review was performed about the "introduction of new technology" to identify challenges. Cross-referencing was used to explore the possible solutions per challenge.

RESULTS

Several characteristics of the surgical craft itself limit our ability to establish randomised controlled trials and hence provide clear categorical evidence. Existing certification bodies for new technology often use unstructured regulations and allow fast-track bypassing systems. Consequently the IDEAL framework (innovation, development, exploration, assessment, long-term follow-up) proposes an objective scientific approach whilst defining stakeholder responsibilities. The selection of which new modality to implement is heavily influenced by third parties unrelated to the best patient outcomes and thus professional organisations can aid in this decision-making. Appropriate training of surgeons and their teams until proficiency is achieved is essential prior to credentialling. Finally long-term surveillance of outcomes in the form of registries is an increasing responsibility of the urological community to maintain our role in directing the adoption or rejection of these innovations.

CONCLUSION

Urological innovation is a dynamic and challenging process. Increasing efforts are identified within the urological community to render the process more reliable and transparent.