Surgical treatment of localized prostate cancer

A clinically relevant formulation for direct administration of nerve specific fluorophores to mitigate iatrogenic nerve injury

Iatrogenic nerve injury significantly affects surgical outcomes. Although intraoperative neuromonitoring is utilized, nerve identification remains challenging and the success of nerve sparing is strongly correlated with surgeon experience levels. Fluorescence guided surgery (FGS) offers a potential solution for improved nerve sparing by providing direct visualization of nerve tissue intraoperatively. However, novel probes for FGS face a long regulatory pathway to achieve clinical translation. Herein, we report on the development of a clinically-viable, gel-based formulation that enables direct administration of nerve-specific probes for nerve sparing FGS applications, facilitating clinical translation via the exploratory investigational new drug (eIND) guidance. The developed formulation possesses unique gelling characteristics, allowing it to be easily spread as a liquid followed by rapid gelling for subsequent tissue hold. Optimization of the direct administration protocol with our gel-based formulation enabled a total staining time of 1-2 min for compatibility with surgical procedures and successful clinical translation.

Direct Administration of Nerve-Specific Contrast to Improve Nerve Sparing Radical Prostatectomy

Nerve damage remains a major morbidity following nerve sparing radical prostatectomy, significantly affecting quality of life post-surgery. Nerve-specific fluorescence guided surgery offers a potential solution by enhancing nerve visualization intraoperatively. However, the prostate is highly innervated and only the cavernous nerve structures require preservation to maintain continence and potency. Systemic administration of a nerve-specific fluorophore would lower nerve signal to background ratio (SBR) in vital nerve structures, making them difficult to distinguish from all nervous tissue in the pelvic region. A direct administration methodology to enable selective nerve highlighting for enhanced nerve SBR in a specific nerve structure has been developed herein. The direct administration methodology demonstrated equivalent nerve-specific contrast to systemic administration at optimal exposure times. However, the direct administration methodology provided a brighter fluorescent nerve signal, facilitating nerve-specific fluorescence imaging at video rate, which was not possible following systemic administration. Additionally, the direct administration methodology required a significantly lower fluorophore dose than systemic administration, that when scaled to a human dose falls within the microdosing range. Furthermore, a dual fluorophore tissue staining method was developed that alleviates fluorescence background signal from adipose tissue accumulation using a spectrally distinct adipose tissue specific fluorophore. These results validate the use of the direct administration methodology for specific nerve visualization with fluorescence image-guided surgery, which would improve vital nerve structure identification and visualization during nerve sparing radical prostatectomy.

Patients' and urologists' preferences for prostate cancer treatment: a discrete choice experiment

Background:

Patients' preferences are important for shared decision making. Therefore, we investigated patients' and urologists' preferences for treatment alternatives for early prostate cancer (PC).

Methods:

A discrete choice experiment was conducted among 150 patients who were waiting for their biopsy results, and 150 urologists. Regression analysis was used to determine patients' and urologists' stated preferences using scenarios based on PC treatment modality (radiotherapy, surgery, and active surveillance (AS)), and risks of urinary incontinence and erectile dysfunction.

Results:

The response rate was 110 out of 150 (73%) for patients and 50 out of 150 (33%) for urologists. Risk of urinary incontinence was an important determinant of both patients' and urologists' stated preferences for PC treatment (P<0.05). Treatment modality also influenced patients' stated preferences (P<0.05), whereas the risk of erectile dysfunction due to radiotherapy was mainly important to urologists (P<0.05). Both patients and urologists preferred AS to radical treatment, with the exception of patients with anxious/depressed feelings who preferred radical treatment to AS.

Conclusion:

Although patients and urologists generally may prefer similar treatments for PC, they showed different trade-offs between various specific treatment aspects. This implies that urologists need to be aware of potential differences compared with the patient's perspective on treatment decisions in shared decision making on PC treatment.

Has the advent of minimally invasive surgery altered the risk profile of patients undergoing prostatectomy?

OBJECTIVES

To determine whether the decreased short-term morbidity associated with minimally invasive surgery (MIS) has resulted in an alteration in the disease-specific risk profile of prostatectomy patients. MIS in many fields has resulted in an expansion in the pool of patients willing to undergo surgery.

METHODS

The Columbia Urologic Oncology Database was queried, and 1751 patients undergoing radical prostatectomy between 2000 and 2007 were identified. The cohort was divided into 2 groups: patients who received surgery before or after the initiation of robotic-assisted laparoscopic radical prostatectomy (RALRP) at our institution (from 2003 onward). Age at surgery, Kattan Nomogram (KN) score, prostate-specific antigen (PSA), Gleason score sum, and tumor stage were compared using unpaired t tests with Welch correction and Mann-Whitney tests.

RESULTS

A total of 663 patients underwent prostatectomy from 2000 to 2002 ("pre-MIS era"), and 1088 patients had surgery in 2003 or later ("MIS era"), of which 519 and 569 underwent RALRP and open prostatectomy, respectively. There was no significant difference between the 2 eras regarding age, Kattan Nomogram score, or tumor stage. However, there was a significant difference in preoperative PSA (P = .01) and Gleason sum (P = .0002). In a comparison of the pre-MIS era with RALRP patients, only PSA differed significantly (P = .0002).

CONCLUSIONS

The advent of MIS for prostate cancer did not significantly alter the characteristics of patients undergoing prostatectomy at our institution. Although advancements in surgical techniques may improve clinical outcomes, this study does not suggest a consequential effect on the risk stratification of patients choosing surgery for prostate cancer.

2,2-bis(4-chlorophenyl)-1,1-dichloroethylene stimulates androgen independence in prostate cancer cells through combinatorial activation of mutant androgen receptor and mitogen-activated protein kinase pathways

Therapy resistance represents a major clinical challenge in disseminated prostate cancer for which only palliative treatment is available. One phenotype of therapy-resistant tumors is the expression of somatic, gain-of-function mutations of the androgen receptor (AR). Such mutant receptors can use noncanonical endogenous ligands (e.g., estrogen) as agonists, thereby promoting recurrent tumor formation. Additionally, selected AR mutants are sensitized to the estrogenic endocrine-disrupting compound (EDC) bisphenol A, present in the environment. Herein, screening of additional EDCs revealed that multiple tumor-derived AR mutants (including T877A, H874Y, L701H, and V715M) are sensitized to activation by the pesticide 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE), thus indicating that this agent may impinge on AR signaling in cancer cells. Further investigation showed that DDE induced mutant AR recruitment to the prostate-specific antigen regulatory region, concomitant with an enhancement of target gene expression, and androgen-independent proliferation. By contrast, neither AR activation nor altered cellular proliferation was observed in cells expressing wild-type AR. Activation of signal transduction pathways was also observed based on rapid phosphorylation of mitogen-activated protein kinase (MAPK) and vasodilator-stimulated phosphoprotein, although only MAPK activation was associated with DDE-induced cellular proliferation. Functional analyses showed that both mutant AR and MAPK pathways contribute to the proliferative action of DDE, as evidenced through selective abrogation of each pathway. Together, these data show that exposure to environmentally relevant doses of EDCs can promote androgen-independent cellular proliferation in tumor cells expressing mutant AR and that DDE uses both mutant AR and MAPK pathways to exert its mitogenic activity.

Preliminary results of intraoperative photodynamic therapy with 5-aminolevulinic acid in dogs with prostate carcinoma

Six client-owned dogs with prostate carcinoma were treated with a combination of (1) partial subcapsular prostatectomy using an Nd:YAG laser, (2) intraoperative photodynamic therapy using a halogen broad band lamp after local administration of a photosensitiser, and (3) systemic treatment with meloxicam. Median survival time was 41days (range 10-68days), which compared negatively with previous reports of subtotal laser prostatectomy combined with topical interleukin-2 administration, and photodynamic therapy alone. Despite treatment, the disease progressed locally, causing signs of stranguria to recur, and in the form of distant metastases. The recurrence of clinical signs due to the primary tumour despite photodynamic therapy is probably largely explained by insufficient penetration of light into the tissue. Better results may be obtained using other light sources (e.g. laser) and alternative techniques of light delivery, such as fibres or catheters allowing interstitial diffusion of light.

[Differential therapy of prostate cancer]

Prostate cancer has become the most common malignancy in males worldwide. Standard therapy in local confined prostate cancer with curative intent is a radical ablation of the gland. Brachytherapy seems to be an alternative treatment but long-term results are not yet available. In cases of advanced disease androgen deprivation is applied to eliminate testosterone which is the natural stimulator of tumor growth. The application of chemotherapy is limited to androgen-independent disease without curative intention. Standard chemotherapy is Docetaxel. Both early detection and aftercare are based on measurement of prostate-specific antigen.

The value of three-dimensional transrectal ultrasonography in staging prostate cancer

OBJECTIVE

To use three-dimensional transrectal ultrasonography (3D-TRUS) to reconstruct the prostate, and thus determine its value in staging clinically localized prostate cancer.

PATIENTS AND METHODS

In all, 180 patients with newly diagnosed clinically localized prostate cancer were assessed using 3D-TRUS for staging. TRUS findings were compared with histopathological staging after radical prostatectomy.

RESULTS

Pathological staging of specimens showed extracapsular extension in 69 patients, of whom 53 had pathological capsular perforation and 16 had seminal vesicle invasion. 3D-TRUS identified 58 patients with sites of extracapsular extension with 84% sensitivity, 96% specificity, 94% positive predictive value, 91% negative predictive value and an overall accuracy of 92%. Of the 16 patients with seminal vesicle invasion 14 were identified correctly on 3D-TRUS. Overall the 3D-TRUS staging sensitivity was 84%, specificity 96%, positive predictive value 93%, negative predictive value 91% and accuracy 91%.

CONCLUSIONS

3D-TRUS seems to be an accurate technique for staging localized prostate cancer. If 3D-TRUS indicates locally advanced disease, the probability of capsular perforation or seminal vesicle invasion is very high.

PSA doubling time predicts the outcome after active surveillance in screening-detected prostate cancer: results from the European randomized study of screening for prostate cancer, Sweden section

This study reports the outcome of active surveillance in men with PSA screening-detected prostate cancer (PC), and PSA doubling time (PSADT) was evaluated as a predictor of selecting patients to active treatment or surveillance. On December 31, 1994, 10,000 men were randomized to biennial PSA testing. Through to December 2004, a total of 660 men were diagnosed with PC, of whom 270 managed with initial surveillance. Of these 270 patients, 104 (39%) received active treatment during follow-up, 70 radical prostatectomy, 24 radiation and 10 endocrine treatment. Those who received active treatment during follow-up (mean 63 months) were significantly younger (62.6 vs. 65.5 years, p < 0.0001) and had a shorter PSADT (3.7 vs. 12 years, p < 0.0001). PSA relapse was observed in 9 of 70 patients who received RRP during a mean follow-up of 37 months. Seven of these nine PSA relapses were in the patients with preoperative PSADT < 2 years. None of the 37 operated patients with a PSADT > 4 years had a PSA relapse. In a Cox regression analysis adjusted for PSA, ratio-free PSA and amount of cancer in biopsy, only the preoperative PSADT was statistically significant predictor of PSA relapse in p = 0.031. The optimal candidate for surveillance is a man with early, low-grade, low-stage PC and a PSADT > 4 years. In younger men with a PSADT of less than 4 years, surveillance does not seem to be a justified alternative, and patient should be informed about the risk with such an approach.

Bisphenol A facilitates bypass of androgen ablation therapy in prostate cancer

Prostatic adenocarcinomas depend on androgen for growth and survival. First line treatment of disseminated disease exploits this dependence by specifically targeting androgen receptor function. Clinical evidence has shown that androgen receptor is reactivated in recurrent tumors despite the continuance of androgen deprivation therapy. Several factors have been shown to restore androgen receptor activity under these conditions, including somatic mutation of the androgen receptor ligand-binding domain. We have shown previously that select tumor-derived mutants of the androgen receptor are receptive to activation by bisphenol A (BPA), an endocrine-disrupting compound that is leached from polycarbonate plastics and epoxy resins into the human food supply. Moreover, we have shown that BPA can promote cell cycle progression in cultured prostate cancer cells under conditions of androgen deprivation. Here, we challenged the effect of BPA on the therapeutic response in a xenograft model system of prostate cancer containing the endogenous BPA-responsive AR-T877A mutant protein. We show that after androgen deprivation, BPA enhanced both cellular proliferation rates and tumor growth. These effects were mediated, at least in part, through androgen receptor activity, as prostate-specific antigen levels rose with accelerated kinetics in BPA-exposed animals. Thus, at levels relevant to human exposure, BPA can modulate tumor cell growth and advance biochemical recurrence in tumors expressing the AR-T877A mutation.