Nerve-sparing focal cryoablation of prostate cancer

The Assessment of a Novel Endoscopic Ultrasound-Compatible Cryocatheter to Ablate Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease that may be treated utilizing thermal therapies. Cryoablation is an effective, minimally invasive therapy that has been utilized for the treatment of various cancers, offering patients a quicker recovery and reduced side effects. Cryoablation has been utilized on a limited basis for the treatment of PDAC. With the recent reports on the success of cryoablation, there is a growing interest in the use of cryoablation as a standalone, minimally invasive procedure to treat PDAC. While offering a promising path, the application of cryoablation to PDAC is limited by current technologies. As such, there is a need for the development of new devices to support advanced treatment strategies for PDAC. To this end, this study investigated the performance of a new endoscopic ultrasound-compatible cryoablation catheter technology, FrostBite. We hypothesized that FrostBite would enable the rapid, effective, minimally invasive delivery of ultra-cold temperatures to target tissues, resulting in effective ablation via an endoscopic approach. Thermal properties and ablative efficacy were evaluated using a heat-loaded gel model, tissue-engineered models (TEMs), and an initial in vivo porcine study. Freeze protocols evaluated included single and repeat 3 and 5 min applications. Isotherm assessment revealed the generation of a 2.2 cm diameter frozen mass with the -20 °C isotherm reaching a diameter of 1.5 cm following a single 5 min freeze. TEM studies revealed the achievement of temperatures ≤ -20 °C at a diameter of 1.9 cm after a 5 min freeze. Fluorescent imaging conducted 24 h post-thaw demonstrated a uniformly shaped ellipsoidal ablative zone with a midline diameter of 2.5 cm, resulting in a total ablative volume of 6.9 cm3 after a single 5 min freeze. In vivo findings consistently demonstrated the generation of ablative areas measuring 2.03 cm × 3.2 cm. These studies demonstrate the potential of the FrostBite cryocatheter as an endoscopic ultrasound-based treatment option. The data suggest that FrostBite may provide for the rapid, effective, controllable freezing of cancerous pancreatic and liver tissues. This ablative power also offers the potential of improved safety margins via the minimally invasive nature of an endoscopic ultrasound-based approach or natural orifice transluminal endoscopic surgery (NOTES)-based approach. The results of this pre-clinical feasibility study show promise, affirming the need for further investigation into the potential of the FrostBite cryocatheter as an advanced, minimally invasive cryoablative technology.

Evaluation of a Novel Cystoscopic Compatible Cryocatheter for the Treatment of Bladder Cancer

BACKGROUND: As the acceptance of cryoablative therapies for the treatment of non-metastatic cancers continues to grow, avenues for novel cryosurgical technologies and approaches have opened. Within the field of genitourinary tumors, cryosurgical treatments of bladder cancers remain largely investigational. Current modalities employ percutaneous needles or transurethral cryoballoons or sprays, and while results have been promising, each technology is limited to specific types and stages of cancers. OBJECTIVE: This study evaluated a new, self-contained transurethral cryocatheter, FrostBite-BC, for its potential to treat bladder cancer. METHODS: Thermal characteristics and ablative capacity were assessed using calorimetry, isothermal analyses, in vitro 3-dimensional tissue engineered models (TEMs), and a pilot in vivo porcine study. RESULTS: Isotherm assessment revealed surface temperatures below – 20°C within 9 sec. In vitro TEMs studies demonstrated attainment of ≤– 20°C at 6.1 mm and 8.2 mm in diameter following single and double 2 min freezes, respectively. Fluorescent imaging 24 hr post-thaw revealed uniform, ablative volumes of 326.2 mm3 and 397.9 mm3 following a single or double 2 min freeze. In vivo results demonstrated the consistent generation of ablative areas. Lesion depth was found to correlate with freeze time wherein 15 sec freezes resulted in ablation confined to the sub-mucosa and ≥30 sec full thickness ablation of the bladder wall. CONCLUSIONS: These studies demonstrate the potential of the FrostBite-BC cryocatheter as a treatment option for bladder cancer. Although preliminary, the outcomes of these studies were encouraging, and support the continued investigation into the potential of the FrostBite-BC cryocatheter as a next generation, minimally invasive cryoablative technology.

Hemiablation of Localized Prostate Cancer by High-Intensity Focused Ultrasound: A Series of 35 Cases

Prostate cancer (PrC) is one of the most common tumors diagnosed in men. The detection rate of localized PrC has been dramatically enhanced by screening and the development of visualization methods. There are currently several techniques for focal treatment available, among which the most interesting in our opinion is high-intensity focused ultrasound (HIFU). Currently, HIFU hemiablation of PrC is not an established treatment, although evidence of its effectiveness and safety is growing. We have been performing HIFU hemiablation since 2013 and here report our results to add to the evidence on the effectiveness of the technique. Between October 2013 and December 2016, we performed HIFU hemiablation of the prostate for a total of 35 patients with confirmed PrC stage <cT2a at our urology clinic and retrospectively examined duration of ablation, pre- and postoperative prostate-specific antigen (PSA) levels, prostate volume, erectile function, and dysuria. The mean duration of ablation was 22 min (10-35). The mean postoperative hospital stay was 4 days. None of the patients experienced serious complications. Postoperative PSA tests showed the greatest decrease after 3 months to 2.4 ng/mL on average (p < 0.001). The pathological focus seen on MRI before the procedure in each case was absent after 3 months. Control biopsy after 12 months revealed residual cancer in the contralateral lobe in 4 patients. The findings obtained during follow-up and from control biopsies indicate that the treatment was highly efficacious with a low rate of nonserious postoperative complications. HIFU hemiablation proved to be a reliable therapeutic modality for localized PrC and was associated with a low rate of complications and comparable risk of recurrence. Despite the fact that this method of treatment is currently experimental, the results of this case series and other studies indicate its feasibility and safety.

Endorectal MRI and MR spectroscopic imaging of prostate cancer: developing selection criteria for MR-guided focal therapy

PURPOSE

To investigate criteria that can identify dominant treatable prostate cancer foci with high certainty at endorectal magnetic resonance imaging (MRI) and MR spectroscopic (MRS) imaging, and thus facilitate selection of patients who are radiological candidates for MR-guided focal therapy.

MATERIALS AND METHODS

We retrospectively identified 88 patients with biopsy-proven prostate cancer who underwent endorectal MRI and MRS imaging prior to radical prostatectomy with creation of histopathological tumor maps. Two independent readers noted the largest tumor foci at MRI, if visible, and the volume of concordant abnormal tissue at MRS imaging, if present. A logistic random intercept model was used to determine the association between clinical and MR findings and correct identification of treatable (over 0.5 cm3) dominant intraprostatic tumor foci.

RESULTS

Readers 1 and 2 identified dominant tumor foci in 50 (57%) and 58 (65%) of 88 patients; 42 (84%) and 48 (83%) of these were dominant treatable lesions at histopathology, respectively. Within the statistical model, the volume of concordant spectroscopic abnormality was the only factor that predicted correct identification of a dominant treatable lesion on T2-weighted images (odds ratio=1.75; 95% confidence interval=1.08 to 2.82; P value=0.02). In particular, all visible lesions on T2-weighted imaging associated with at least 0.54 cm3 of concordant spectroscopic abnormality were correctly identified dominant treatable tumor foci.

CONCLUSION

Patients with dominant intraprostatic tumor foci seen on T2-weighted MRI and associated with at least 0.54 cm3 of concordant MRS imaging abnormality may be radiological candidates for MR-guided focal therapy.

Parameters predicting postoperative unilateral disease in patients with unilateral prostate cancer in diagnostic biopsy: a rationale for selecting hemiablative focal therapy candidates

BACKGROUND

Focal hemiablative therapy for prostate cancer is a new treatment alternative. Unilateral and unifocal disease are its main limitations. The aim of this study was to identify the epidemiological, clinical and pathological parameters that may predict unilateral disease in patients diagnosed with prostate cancer.

METHODS

We performed a retrospective analysis of patients at our institution between January 2005 and January 2011. Only patients with unilateral disease in prostate biopsy were part of the study. The analysis included age, preoperative prostate-specific antigen (PSA) and its density, prostate volume, biopsy first and second Gleason pattern and Gleason summary, number of biopsy cores, percentage of cancer in biopsy material and the presence of high-grade prostatic intraepithelial neoplasia. Their role as potential predictors was evaluated by univariate and multivariate analysis.

RESULTS

A total of 161 patients had unilateral disease after prostate biopsy. A significant correlation was found between prostate volume, PSA density and percentage of cancer in biopsy material and the presence of unilateral disease in the surgical specimen. These are the same factors significant in the univariate analysis. The results of the multivariate analysis demonstrated that PSA density (p = 0.015) and percentage of cancer in biopsy material (p = 0.028) are the most significant predictors.

INTERPRETATION

Our results demonstrate that PSA density and the percentage of cancer in biopsy cores are significant predictors for prostate cancer unilaterality and should be considered for the selection of hemiablative focal therapy candidates.

Focal therapy for prostate cancer: patient selection and evaluation

Recent stage migration toward low-risk prostate cancer, overtreatment of biologically insignificant tumors with radical prostatectomy at the additional expense of a non-negligible morbidity and undertreatment of patients improperly selected for active surveillance are the main reasons that have fueled the concept of focal therapy. Optimal selection of patients is the key for the successful implementation of focal therapy. Selection criteria for focal therapy vary widely and depend on clinical, histological and imaging characteristics of the patients that are highlighted in this article. In addition, the rationales, merits and limitations of the available methods for the assessment of potential candidates, the evaluation of treatment efficacy and follow-up of these patients are discussed.

Pros and cons of focal therapy for localised prostate cancer

In prostate cancer, an interesting and intriguing option to overcome the risks of whole-gland treatment is focal therapy, with the aim of eradicating known cancer foci and reducing collateral damages to the structures essential for maintaining normal urinary and sexual function. Ablation of all known lesions would favorably alter the natural history of the cancer without impacting health-related quality of life and allows for safe retreatment with repeated focal therapy or whole-gland approaches if necessary. Our objective is to reassess the possibilities and criticisms of such procedure: the rationale for focal therapy and the enthusiasm come from the success of conservative approaches in treating other malignancies and in the high incidence of overtreatment introduced by prostate cancer screening programs. One of the challenges in applying such an approach to the treatment of prostate cancer is the multifocal nature of the disease and current difficulties in accurate tumor mapmaking.

Focal therapy in prostate cancer: determinants of success and failure

Focal therapy is emerging as a potential challenge to the standard of care for localized prostate cancer. Short-term quality-of-life outcomes such as genitourinary side effects, anxiety levels, and global measures of quality of life using validated questionnaires are vital although proof-of-concept trials and retrospective case series have already established lower toxicity from focal therapy in some detail. Defining what outcomes will be measured and what defines a successful focal treatment in the medium and long term is problematic. Measuring long-term efficacy or effectiveness within a randomized trial is somewhat straightforward since hard endpoints are measured such as presence or absence of metastatic disease and/or death. However, owing to the long natural history of localized prostate cancer detected in the modern prostate-specific antigen screening era, with these events usually occurring a minimum of 10 years after therapy makes such a long-term trial large, costly, and probably unfeasible now. This article discusses the optimal determinants of success or failure for focal therapy that require careful consideration within multicenter trials evaluating medium-term oncological efficacy.

Impact of prostate cancer multifocality on its biology and treatment

Any focal therapy requires correct localization of the lesion; consequently, much effort is now devoted to accurate characterization of the spatial distribution of the tumor within the prostate. One of the greatest difficulties in the localization of prostate cancer is its frequent multifocality, but prostate cancer is unifocal in 13% to 43.7% of cases and unilateral in 19.2%. In cases of multifocality, it seems that the index tumor is the biologic driving force behind the malignant potential of prostate cancer. Not only is the Gleason score of the secondary nodes lower than that of the index node, but 80% of the secondary nodes are smaller than 0.5 cc and almost all extraprostatic extensions are associated with the largest cancers. While current evaluation with 12 to 18 core biopsies may be adequate to determine the index lesion, transperineal three-dimensional mapping biopsy of the prostate should be undertaken if greater accuracy is needed.

Active hydrodissection might optimize cryosurgical ablation of the prostate

OBJECTIVE

To produce lower temperatures safely in the prostate, and better protect the rectum , as well as maximize the technique of cryosurgical ablation to better eradicate prostate cancer.

METHODS

A total of 10 consecutive patients underwent total, subtotal, or focal cryosurgical ablation, with saline hydrodissection. We found lethal prostate temperatures and safer rectal temperatures. One patient developed a very small rectourethral fistula that healed with catheter drainage alone, prompting a revised technique. The prostate-specific antigen values at short follow-up were very low.

RESULTS

Temperatures of -10°C to -76°C were achieved outside the prostate at the neurovascular bundle. Post-operative prostate-specific antigen values were 0.10 to 3.4 if total or focal therapy, respectively, was used. A small rectal fistula healed with catheter drainage alone.

CONCLUSIONS

This technique appears to hold great promise and should be investigated further in a larger group of patients with longer follow-up.

Is focal therapy the future for prostate cancer?

Focal therapy aims to find a middle ground between surveillance and radical therapies by treating the cancer alone, with a margin, and preserving as much tissue as is practical. Early feasibility studies have demonstrated an absence of rectal toxicity and preservation of genitourinary function in 80–90% of men. The incidence of low- to intermediate-risk prostate cancer is rising owing to informal and formal prostate-specific antigen screening practices. The treatment burden from radical therapies is high with over 50% of men suffering genitourinary or rectal toxicity. Active surveillance, on the other hand, carries surveillance and psychological burden with risk of progression. A research strategy to evaluate focal therapy should be embedded within pragmatic designs using a broad patient group, using the available ablative technologies (cryotherapy, high-intensity focused ultrasound, brachytherapy and photodynamic therapy) with end points derived from biochemical, biopsy and imaging. Within this framework there exists a unique opportunity to undertake landmark diagnostic studies incorporating imaging techniques and biomarkers in addition to studies directed at the biology of prostate cancer over time.

Recent advances in focal therapy of prostate and kidney cancer

The concept of focal therapy in oncologic surgery refers to maximizing healthy tissue preservation while maintaining excellent cancer control outcomes. Herein, we address the recent advantages in the field of focal therapy for both kidney and prostate cancer, focusing on technological achievements and future perspectives.