Focal therapy and imaging in prostate and kidney cancer: high-intensity focused ultrasound ablation of small renal tumors

Polarization-sensitive optical coherence tomography for renal tumor detection in ex vivo human kidneys

Kidney cancer is a kind of high mortality cancer because of the difficulty in early diagnosis and the high metastatic dissemination in treatments. The surgical resection of tumors is the most effective treatment for renal cancer patients. However, precise assessment of tumor margins is a challenge during surgical resection. The objective of this study is to demonstrate an optical imaging tool in precisely distinguishing kidney tumor borders and identifying tumor zones from normal tissues to assist surgeons in accurately resecting tumors from kidneys during the surgery. 30 samples from six human kidneys were imaged using polarization-sensitive optical coherence tomography (PS-OCT). Cross-sectional, enface, and spatial information of kidney samples were obtained for microenvironment reconstruction. Polarization parameters (phase retardation, optic axis direction, and degree of polarization uniformity (DOPU) and Stokes parameters (Q, U, and V) were utilized for multi-parameter analysis. To verify the detection accuracy of PS-OCT, H&E histology staining and dice-coefficient was utilized to quantify the performance of PS-OCT in identifying tumor borders and regions. In this study, tumor borders were clearly identified by PS-OCT imaging, which outperformed the conventional intensity-based OCT. With H&E histological staining as golden standard, PS-OCT precisely identified the tumor regions and tissue distributions at different locations and different depths based on polarization and Stokes parameters. Compared to the traditional attenuation coefficient quantification method, PS-OCT demonstrated enhanced contrast of tissue characteristics between normal and cancerous tissues due to the birefringence effects. Our results demonstrated that PS-OCT was promising to provide imaging guidance for the surgical resection of kidney tumors and had the potential to be used for other human kidney surgeries in clinics such as renal biopsy.

Robotic-assisted partial nephrectomy: experience on 60 cases

INTRODUCTION

Laparoscopic partial nephrectomy is still one of the more challenging procedures in urology. Minimizing warm ischemia time (WIT) and bleeding requires efficient intracorporeal suturing. In addition, achieving negative surgical margins requires complete excision of the tumor. Robotic-assisted partial nephrectomy (RALPN) adds the advantages offered by the "Da Vinci system" to laparoscopy, such as the 3-D vision, and the better degree of freedom of surgical instruments.

OBJECTIVE

The objective of this study is to report our experience with RALPN.

METHODS

From August 2009 to October 2012, 60 patients underwent RALPN for kidney cancer. The average age of the patients (35 female, 25 male) was 63 (range 48-80) years. Average BMI was 25 (range 21.8-29.7) kg/m2. Average tumor size was 3.2 cm (range 2-6.7 cm). All the procedures were performed by a transperitoneal approach. Ilar clamping was used in all cases: in 47 patients by one intracorporeal tourniquet for the artery and one for the vein; in three cases, ilar clamping was "en block" by Satinsky.

RESULTS

Mean operative time was 167.2 min (140-250) with a WIT of 23.8 min (15-28). The mean estimated blood loss was 260 mL (50-300). In one case, nephrectomy was necessary because the tumor involved the renal pedicle. One patient had pulmonary embolism and one urinary leakage conservatively managed.Pathologic examination revealed clear cell renal cell carcinoma in 58 patients, oncocytoma in one patient, and angiomyolipoma in one patient. All resection margins were free from tumor.

CONCLUSIONS

Partial nephrectomy, facilitated by robotic technology, is more and more frequently performed as a safe and effective minimally invasive procedure.

Comparison of Contrast-Enhanced Ultrasound Scan (CEUS) and MRI in the follow-up of cryoablation for small renal tumors. Experience on 25 cases

Introduction

Percutaneous ablation in the kidney is now performed as a standard therapeutic nephron-sparing option in patients who are poor candidates for resection. Its increasing use has been largely prompted by the rising incidental detection of renal cell carcinomas with cross-sectional imaging and the need to preserve renal function in patients with comorbid conditions, multiple renal cell carcinomas, and/or heritable renal cancer syndromes. To date, clinical studies indicate that cryoablation is an effective therapy with acceptable short- to intermediate-term outcomes and with a low risk in the appropriate setting. This article focuses on the efficiency of contrast enhanced ultrasound scan (CEUS) as compared to contrast enhanced magnetic resonance imaging (MRI) during the follow-up after cryoablation of small renal tumors.

Material and Methods

In our Department, percutaneous or laparoscopic assisted cryoablation is offered in the treatment of small renal masses. Between January 2009 and January 2013, 25 patients (pts) were treated with laparoscopic assisted cryoablation or percutaneous cryoablation for renal tumors <3.5 cm in pts unfit for surgery. All pts had severe comorbidities (ASA score 3). Transperitoneal laparoscopic approach was performed in 11 pts, extraperitoneal approach in 3 pts, percutaneous technique was performed in 11 patients. “Tru-cut biopsy” of the renal mass was always performed before cryoablation. The SeedNet system (Galil Medical, Arden Hills, MN) was used in 12/25 pts; the Precise system (Galil Medical, Arden Hills, MN) was used in 13/25 pts. In all cases, IceRod needles were used. Real-time ultrasound guidance was used to localize the tumour and to monitor the progression of “iceball”. A double “freeze-thaw cycle” was used. All pts had MRI and CEUS before cryoablation and the follow-up consisted in CEUS/MRI every 3 months during the first year and every 6 months thereafter.

Results

The mean age of the 25 pts was 67.7 years (range 56–79); 5 pts were females and 20 were males. The mean tumor size was 2.8 cm (range 1.5–3.5). No patient required conversion to open procedure. 19 tumors were located at the lower pole, 4 were interpolar and 2 tumors were located at the upper pole. There were no intraoperative complications. The mean hospital stay was 4 days (range 1–7). Two pts required a blood transfusion; there was no statistically significant difference between preoperative and postoperative serum creatinine levels. The biopsy showed RCC in all cases. In 24/25 patients both CEUS and MRI showed no enhancement. In 1/25 pts, during the follow-up, CEUS and MRI showed a well visible recurrence at the perfusion study. It was histologically confirmed. The final results of CEUS and MRI were concordant in all pts.

Conclusions

CEUS is effective during the follow-up of renal tumor cryoablation. It could be an alternative technique to standard CT and MRI, with some advantages: low cost, short time consuming procedure, no radiation exposure, reduced amount of contrast agent (1–2 mL) and rare adverse reactions.

SonoKnife for ablation of neck tissue: in vivo verification of a computer layered medium model

PURPOSE

This study aimed to determine which treatment parameters of the SonoKnife device can be used to safely and effectively perform non-invasive thermal ablation of subcutaneous tissue.

METHODS

A three-dimensional computational layered medium model was constructed to simulate thermal ablation treatment of the SonoKnife device. The acoustic and thermal fields were calculated with the Fast Object-Oriented C++ Ultrasound-Simulator software and a finite difference code, respectively. Subcutaneous tissue was represented as layers of skin, fat and muscle. The simulations were conducted for ultrasound frequencies of 1 or 3.5 MHz. The thermal dose model was used to predict the size and location of the ablated regions. The computer simulations were verified by using the SonoKnife to perform subcutaneous ablations in the neck area of healthy pigs, in vivo. Triphenyltetrazolium chloride viability stain was used to differentiate viable tissue from ablated regions ex vivo.

RESULTS

The simulations for the layered medium model suggest that operating the SonoKnife at frequency of 1 MHz is more effective and safer than 3.5 MHz providing skin cooling is applied prior to ablation. These predictions were in agreement with the results observed in the animal studies. The required sonication time for ablation increased from 50 to 300 s by using 1 MHz.

CONCLUSION

Our modelling and animal studies suggest that 1 MHz with pretreatment skin cooling are the optimal settings to operate the SonoKnife to safely and effectively perform subcutaneous thermal ablation of porcine skin. More work is needed to optimise skin cooling and define the optimal sonication time.

In vivo antitumor activity of intratumoral fludarabine phosphate in refractory tumors expressing E. coli purine nucleoside phosphorylase

PURPOSE

Systemically administered fludarabine phosphate (F-araAMP) slows growth of human tumor xenografts that express Escherichia coli purine nucleoside phosphorylase (PNP). However, this treatment has been limited by the amount of F-araAMP that can be administered in vivo. The current study was designed to (1) determine whether efficacy of this overall strategy could be improved by intratumoral administration of F-araAMP, (2) test enhancement of the approach with external beam radiation, and (3) optimize recombinant adenovirus as a means to augment PNP delivery and bystander killing in vivo.

METHODS

The effects of systemic or intratumoral F-araAMP in mice were investigated with human tumor xenografts (300 mg), in which 10 % of the cells expressed E. coli PNP from a lentiviral promoter. Tumors injected with an adenoviral vector expressing E. coli PNP (Ad/PNP; 2 × 10(11) viral particles, 2 times per day × 3 days) and the impact of radiotherapy on tumors treated by this approach were also studied. Radiolabeled F-araAMP was used to monitor prodrug activation in vivo.

RESULTS

Intratumoral administration of F-araAMP in human tumor xenografts expressing E. coli PNP resulted in complete regressions and/or prolonged tumor inhibition. External beam radiation significantly augmented this effect. Injection of large human tumor xenografts (human glioma, nonsmall cell lung cancer, or malignant prostate tumors) with Ad/PNP followed by intratumoral F-araAMP resulted in excellent antitumor activity superior to that observed following systemic administration of prodrug.

CONCLUSION

Activation of F-araAMP by E. coli PNP results in destruction of large tumor xenografts in vivo, augments radiotherapy, and promotes robust bystander killing. Our results indicate that intratumoral injection of F-araAMP leads to ablation of tumors in vivo with minimal toxicity.

SonoKnife: feasibility of a line-focused ultrasound device for thermal ablation therapy

PURPOSE

To evaluate the feasibility of line-focused ultrasound for thermal ablation of superficially located tumors.

METHODS

A SonoKnife is a cylindrical-section ultrasound transducer designed to radiate from its concave surface. This geometry generates a line-focus or acoustic edge. The motivation for this approach was the noninvasive thermal ablation of advanced head and neck tumors and positive neck nodes in reasonable treatment times. Line-focusing may offer advantages over the common point-focusing of spherically curved radiators such as faster coverage of a target volume by scanning of the acoustic edge. In this paper, The authors report studies using numerical models and phantom and ex vivo experiments using a SonoKnife prototype.

RESULTS

Acoustic edges were generated by cylindrical-section single-element ultrasound transducers numerically, and by the prototype experimentally. Numerically, simulations were performed to characterize the acoustic edge for basic design parameters: transducer dimensions, line-focus depth, frequency, and coupling thickness. The dimensions of the acoustic edge as a function of these parameters were determined. In addition, a step-scanning simulation produced a large thermal lesion in a reasonable treatment time. Experimentally, pressure distributions measured in degassed water agreed well with acoustic simulations, and sonication experiments in gel phantoms and ex vivo porcine liver samples produced lesions similar to those predicted with acoustic and thermal models.

CONCLUSIONS

Results support the feasibility of noninvasive thermal ablation with a SonoKnife.

Perioperative, oncologic, and functional outcomes of laparoscopic renal cryoablation and open partial nephrectomy: a matched pair analysis

PURPOSE

To directly compare perioperative, oncologic, and functional outcomes of laparoscopic renal cryoablation and open partial nephrectomy using a matched pair analysis.

PATIENTS AND METHODS

A total of 41 patients who underwent laparoscopic cryoablation for an incidental, solid clinical T(1a)N(0)M(0) renal tumor were matched with 82 patients who received partial nephrectomy in cold ischemia, using optimal matching based on propensity scores, which were created on the basis of preoperative aspects and dimensions used for an anatomic classification of renal tumors (PADUA) score, preoperative glomerular filtration rate, age-adjusted Charlson comorbidity index, and sex. Median follow-up was 33.6 months.

RESULTS

No differences in the overall incidence of complications (cryoablation, 20%; partial nephrectomy, 17%; P=0.739) and grade of complications (P=0.424) were observed. After cryoablation, local recurrence developed in four patients with renal-cell carcinoma (n=35) after a median duration of 14 months (range 6-18  mos), but none after partial nephrectomy. The 3-year recurrence-free survival probabilities after laparoscopic renal cryoablation vs open partial nephrectomy were 83% vs 100%, respectively (P=0.015). The average decrease of estimated glomerular filtration rate during follow-up was 7.8±3.1  mL/min/1.73  m(2) after laparoscopic cryoablation and 9.8±2.3  mL/min/1.73  m(2) after open partial nephrectomy, which was not statistically significant (P=0.602).

CONCLUSIONS

Perioperative complications and renal functional outcomes of laparoscopic cryoablation and open partial nephrectomy are similar; however, laparoscopic cryoablation confers a substantially higher local recurrence risk of about 17% after 3 years. Therefore, laparoscopic renal cryoablation should be reserved for high-risk patients with decreased life expectancy. Careful patient counseling is advocated. Study limitations include the small sample size, the lack of randomization, and the short follow-up.

The ongoing history of thermal therapy for cancer

Through 5,000 years of practice, physicians, surgeons, clergy, or lay people have used thermal therapy to treat mass lesions now known as cancer. The methods have changed dramatically over this time span and certainly the techniques have improved the efficacy and safety. Hyperthermia used in combination with chemotherapy or ionizing radiation continues to improve outcomes. The authors briefly describe the historical role of hyperthermia in cancer care as well as modern expectations based on technological advancements. In particular, the article focuses on the role of hyperthermia for cancers that do not have other, more effective treatments.