The current use and future trends of focal surgical therapy in the management of localized prostate cancer

Photodynamic therapy for the precise treatment of localized prostate cancer

Over the past 20 years, early diagnosis of prostate cancer has become increasingly prevalent due to the promotion of prostate-specific antigens, and its treatment has become a focal point. However, there are some drawbacks associated with therapies for early prostate cancer, such as active surveillance and radical prostatectomy, which may include urinary incontinence, erectile dysfunction, and urinary tract infection. In contrast, photodynamic therapy (PDT) is introduced into the treatment of prostate cancer because of its advantages, such as high precision to tumor cells, low toxicity, and no radiation. Compared to radical prostatectomy, the PDT has low risk and minimal trauma. Although PDT is in the early stages of clinical development, it holds promise for the effective treatment of localized prostate cancer. Herein, we reviewed studies on the mechanisms of PDT and photosensitizers for prostate cancer. Given the rapid development of nanotechnology, photosensitizers wrapped by nanomaterials have emerged as new option with significant advantages, particularly of in achieving high tumor selectivity using functional nanomaterials. Numerous PDT clinical trials on prostate cancer have been conducted worldwide. We also reviewed the results of a few photosensitizers in these clinical trials. However, a few limitations and challenges regarding PDT for prostate cancer still exist. In addition, future development and potential clinical application strategies of future PDT are predicted.

Cryotherapy in prostate cancer

Review objectives:

Cryotherapy use has increased due to technological advances. A review of the literature was performed to evaluate the efficacy and outcomes of whole gland, salvage and targeted focal cryotherapy in the management of prostate cancer.

Review findings:

Cryotherapy use has increased significantly over the last 10 years with a trend towards focal ablation. Whole gland cryotherapy, salvage cryotherapy and focal cryotherapy biochemical recurrence rates appear to be comparable to other treatment modalities for low risk disease, however biochemical failure remains difficult to compare across studies due to a lack of consensus regarding appropriate end points for evaluation of cryotherapy. Short-term focal cryotherapy outcomes are encouraging. Side effect profiles for cryotherapy have significantly improved with fourth generation systems while salvage cryotherapy continues to carry a slightly higher risk of incontinence than primary whole gland cryotherapy. The incidence of erectile dysfunction after focal cryotherapy is dramatically lower than that for whole gland ablation.

Conclusions:

Cryotherapy continues to have an active role in the primary and salvage treatment of prostate cancer. Targeted focal cryotherapy is a promising treatment with minimal morbidity. Further long-term data is needed to support targeted therapy in addition to direct comparison with other treatment modalities.

Diffuse optical tomography to monitor the photocoagulation front during interstitial photothermal therapy: Numerical simulations and measurements in tissue-simulating phantoms

Near-infrared interstitial photothermal therapy (PTT) is currently undergoing clinical trials as an alternative to watchful waiting or radical treatments in patients with low/intermediate-risk focal prostate cancer. Currently, magnetic resonance imaging (MRI)-based thermography is used to monitor thermal energy delivery and determine indirectly the completeness of the target tumor destruction while avoiding damage to adjacent normal tissues, particularly the rectal wall. As an alternative, transrectal diffuse optical tomography (TRDOT) is being developed to image directly the photocoagulation boundary based on the changes in tissue optical properties, particularly scattering. An established diffusion-theory finite-element software platform was used to perform forward simulations to determine the sensitivity of changes in the optical signal resulting from a growing coagulated lesion with optical scattering contrast, for varying light source-detector separations in both longitudinal and transverse imaging geometries. The simulations were validated experimentally in tissue-simulating phantoms using an existing continuous-wave TRDOT system, in a configuration that is representative of one potential intended clinical use. This provides critical guidance for the optimum design of the transrectal applicator probe, in terms of achieving maximum sensitivity to the presence of the coagulation boundary and, consequently, the highest accuracy in determining the boundary location relative to the rectal wall.

Pelvic applications of MR-guided high intensity focused ultrasound

MR-guided high intensity focused ultrasound (MRg HIFU) is a novel method of tissue ablation that incorporates high energy focused ultrasound for tissue heating and necrosis within an MR scanner that provides simultaneous stereotactic tissue targeting and thermometry. To date, MRg HIFU has been used primarily to treat uterine fibroids, but many additional applications in the pelvis are in development. This article reviews the basic technology of MRg HIFU, and the use of MRg HIFU to treat uterine fibroids, adenomyosis, and prostate cancer.

Prostate saturation biopsy following a first negative biopsy: state of the art

INTRODUCTION

Saturation prostate biopsy (SPBx) has been initially introduced to improve prostate cancer (PCa) detection rate (DR) in the repeat setting. Nevertheless, the optimal number and the most appropriate location of the cores, together with the timing to perform a second PBx and the eventual modification of the PBx protocols according to the different clinical situations, are matters of debate. The aim of this review is to perform a critical analysis of the literature about the actual role of SPBx in the repeat setting.

MATERIALS AND METHODS

We performed a systematic review of the literature since 1995 up to 2011. Electronic searches were limited to the English language, using the MEDLINE database. The key words 'saturation prostate biopsy' and 'repeated prostate biopsy' were used.

RESULTS

SPBx improves PCa DR if clinical suspicion persists after previous biopsy with negative findings and provides an accurate prediction of prostate tumor volume and grade, even if the issue about the number and locations of the cores is still a matter of debate.

CONCLUSIONS

At present, SPBx seems to be really necessary in men with persistent suspicion of PCa after negative initial biopsy and probably in patients with a multifocal high-grade prostatic intraepithelial neoplasia or atypical small acinar proliferation. In the remaining situations, adopting an individualized scheme is preferable.

Histological characteristics of the index lesion in whole-mount radical prostatectomy specimens: implications for focal therapy

It has been suggested that in multifocal prostate cancer (PCa), focal therapy to the largest (index) lesion is sufficient, because secondary non-index lesions are unlikely to contribute to disease progression. In this study, the role of PCa focality in selecting men for focal therapy was evaluated. A histopathological analysis of the index and non-index lesions of 100 consecutive radical prostatectomy specimens was carried out. Cases that would have been suitable for focal ablation were also evaluated. Tumours were more often multifocal (78%) and bilateral (86%). In total, 270 tumour foci were identified. In multifocal disease, tumour volume, Gleason score and pathological stage were almost invariably defined by the index lesion of the specimen; among the 170 satellite foci, 148 (87%) were <0.5 cm(3) and 169 (99.4%) had Gleason score ≤ 6. Using the defined criteria, 51% of men in this series would have been considered suitable for focal ablation of the index lesion. Histological features of poor prognosis in the prostate are associated with the index lesion. There is a high proportion of patients who may be suitable for focal therapy, and clinical trials of index lesion ablation should be considered as part of this therapeutic strategy.

The role of transrectal saturation biopsy in tumour localization: pathological correlation after retropubic radical prostatectomy and implication for focal ablative therapy

OBJECTIVE

• To evaluate the accuracy of an initial 24-core prostate biopsy scheme (PBx24) in predicting unilateral prostate cancer (PCa) in radical prostatectomy (RP) specimens.

PATIENTS AND METHODS

• Between 2005 and 2008, 203 consecutive patients underwent PBx24 followed by RP for PCa. The area under the curve (AUC) was used to evaluate the accuracy of unilateral PCa on PBx24 to predict unilateral PCa in RP specimens. • The positive predictive value (PPV) and negative predictive value (NPV) were also calculated. Moreover, in patients with unilateral PCa on biopsy, univariable and multivariable logistic regression analyses tested the relationship between the presence of unilateral PCa in an RP specimen and the variables: age, prostate-specific antigen (PSA), total prostate volume, clinical stage, primary Gleason grade, secondary Gleason grade and the number of positive cores.

RESULTS

• PCa cores were unilateral in 115 patients (56.7%) on biopsy. Of those, only 26 (22.6%) had unilateral PCa in the RP specimen (AUC, 72.9%; PPV, 22.6%; NPV, 98.8%). In patients with clinically low-risk tumours, only 17 of 63 (27%) had a unilateral PCa on PBx24 and in the RP specimen (AUC, 59.1%; PPV, 27.0%; NPV, 100.0%). • None of the examined variables was an independent predictor of the presence of unilateral PCa in the RP specimen (all P > 0.05).

CONCLUSIONS

• Initial PBx24 is not sufficiently accurate to be dependable as a method of predicting tumour laterality in RP specimens. Therefore, the use of PBx24 to guide hemi-ablation therapy of PCa may lead to mistreatment in a considerable proportion of patients. • Moreover, none of the routinely available clinical and pathological characteristics appears to improve the ability of unilateral PCa on biopsy to predict unilateral PCa in the RP specimen.

Contrast-enhanced ultrasonography evaluation of radiofrequency ablation of the prostate: a canine model

BACKGROUND AND PURPOSE

Currently, there is no reliable method of monitoring the propagation of radiofrequency lesions in real time. We report our animal experience using contrast-enhanced ultrasonography (CEUS) to evaluate the lesion produced by radiofrequency ablation (RFA) in a canine model and investigate the feasibility to predict these lesions.

MATERIALS AND METHODS

Five male beagle dogs underwent RFA of the prostate. Radiofrequency was delivered under transrectal ultrasonography guidance. We created a lesion in the right and left lateral lobes of canine prostate. Post-RFA lesion size was measured with conventional ultrasonography and contrast-enhanced low-mechanical index perfusion imaging (ESAOTE DU8, CnTI) with a second-generation contrast agent (Sonovue). The prostates were assessed for a contrast void corresponding to the ablated tissue. All dogs were then immediately killed, and the prostates were harvested for pathologic analysis. The gross RFA lesions were measured to compare lesion size with that measured using CEUS.

RESULTS

The RFA lesions could not be imaged accurately in real time with conventional grayscale or power Doppler sonography. With CEUS imaging, a clear lesion was identified at the site of each RFA application. As measured by CEUS, the lesions volume averaged 1.30 +/- 0.50 cm(3), compared with 1.32 +/- 0.53 cm(3) by measurement in the gross specimen (p = 0.324).

CONCLUSIONS

CEUS appears to be an accurate modality for immediate monitoring of RFA procedure. Further study is necessary to assess the clinical utility of CEUS for monitoring RFA of localized prostate cancer.

Microwave tissue ablation: biophysics, technology, and applications

Microwave ablation is an emerging treatment option for many cancers, cardiac arrhythmias, and other medical conditions. During treatment, microwaves are applied directly to tissues to produce rapid temperature elevations sufficient to produce immediate coagulative necrosis. The engineering design criteria for each application differ, with individual consideration for factors such as desired ablation zone size, treatment duration, and procedural invasiveness. Recent technological developments in applicator cooling, power control, and system optimization for specific applications promise to increase the utilization of microwave ablation in the future. This article reviews the basic biophysics of microwave tissue heating, provides an overview of the design and operation of current equipment, and outlines areas for future research.

Nerve-sparing focal cryoablation of prostate cancer

PURPOSE OF REVIEW

We evaluate the rationale, candidate selection, and results of the first clinical studies of focal cryoablation for select patients with low volume and low-to-low - moderate risk features of prostate cancer as a possible alternative to whole gland treatment.

RECENT FINDINGS

For a select cohort of patients with low-to-low - moderate risk unifocal or unilateral prostate cancer, a number of ablative treatment options for focal therapy are available with cryotherapy having the most clinical experience. However, retrospective pathological data from large prostatectomy series do not clearly reveal valid and reproducible criteria to select appropriate candidates for focal cryoablation due to the complexity of tumorigenesis in early stage disease.

SUMMARY

The concept of focal therapy is evolving with the understanding of the biologic variability (clinically aggressive, significant, or insignificant) of prostate cancers that may require different treatment approaches. Minimally-invasive, parenchyma-preserving cryoablation can be considered as a potential feasible option in the treatment armamentarium of early stage, localized prostate cancer in appropriately selected candidates.

Prostate cancer: the new landscape

PURPOSE OF REVIEW

This review highlights current features of the changing landscape of the US population with newly diagnosed prostate cancer and discusses new treatment options utilizing noninvasive or minimally invasive management.

RECENT FINDINGS

Recent evidence of significant changes in the current prostate cancer landscape is based on clinical data and pathological specimens after radical prostatectomy that suggest a further increase of the low-risk patient population that may require reconsideration of treatment options. For a select cohort of patients with low-risk features, based on the D'Amico definition, active surveillance or focal ablative therapy may be a rational alternative to surgical prostatectomy or whole-gland radiation therapy that still dominate as the main treatment approaches for localized prostate cancer.

SUMMARY

As the prostate-specific antigen era continues to mature, we continue to witness stage migration. A growing segment of the localized prostate cancer patient population has very low-volume, low-grade disease. Although active surveillance may be an appropriate approach for a selected group of patients, the progression requiring whole-gland therapy remains a challenge. Organ-sparing focal therapy might ideally fill the gap between a surveillance strategy and whole-gland treatment providing a reasonable balance between cancer control and quality of life.

L-type amino-acid transporter 1 as a novel biomarker for high-grade malignancy in prostate cancer

To find reliable biomarkers for high-grade malignancy, the relationship between immunohistochemical L-type amino-acid transporter 1 (LAT1) expression of biopsy samples, determined with the newly developed monoclonal antibody against human LAT1, and prognosis of patients with prostate cancer, was investigated. The intensity and score of immunohistochemical LAT1 expression of first biopsy samples were assessed using the modified Sinicrope et al. method and were found to be correlated with poor survival for the study group of 114 surgically treated patients as a whole (P = 0.0002 and 0.0270, respectively). LAT1 intensity further had a significant relationship (P = 0.0057) with prognosis in pathological T3 + T4 groups. Multivariate analysis indicated that the LAT1 intensity and score were more reliable prognostic markers, compared with the Gleason score and the Ki-67 labeling index. A relationship of the LAT1 intensity and score with prognosis could also be confirmed in 63 patients with inoperable cancer (P = 0.0070 and <0.0001, respectively). Similarly, significant differences in prognosis were confirmed in clinical T3 + T4 groups (P = 0.0091 and 0.0244, respectively). Moreover, the combination of LAT1 expression and Gleason score was found to have a more reliable correlation with prognosis. Thus, elevated LAT1 expression in prostate cancers is a novel independent biomarker of high-grade malignancy, which can be utilized together with the Gleason score, which is mainly dependent on cellular and structural atypia, to assess prognosis.

Antitumour effect of electrochemotherapy with bleomycin on human prostate cancer xenograft

OBJECTIVE

To investigate the antitumour effect of electroporation (EP), a drug delivery system that has been shown to be effective synergistically with antitumour drugs, with bleomycin on the growth of prostate cancer xenografts in nude mice.

MATERIALS AND METHODS

PC-3 cells were implanted subcutaneously into nude mice. After determination of the optimal conditions of electric pulse voltage and bleomycin dose, tumour growth in mice treated with EP plus bleomycin was compared with that in mice receiving EP alone, bleomycin alone or no treatment. In all four groups, apoptosis in the tumours was assessed.

RESULTS

There was a significant reduction in tumour growth in mice that received EP with bleomycin. Apoptotic cells in tumours at 24 h after treatment with EP plus bleomycin showed a significant difference compared with the other three groups, but not at 12 h after treatment.

CONCLUSIONS

These results indicate the possibility that EP with bleomycin could be effective as an ablation therapy for prostate cancer, especially androgen-independent cancer.