Current Topics in the Treatment of Prostate Cancer with Low-Dose-Rate Brachytherapy

Lung cancer metastasis-related protein 1 promotes the transferring from advanced metastatic prostate cancer to castration-resistant prostate cancer by activating the glucocorticoid receptor α signal pathway

Androgen deprivation therapy is currently the main therapeutic strategy for the treatment of advanced metastatic prostate cancer (ADPC). However, the tumor type in ADPC patients transforms into castration-resistant prostate cancer (CRPC) after 18–24 months of treatments, the underlying mechanism of which remains unclear. The present study aimed to investigate the potential pathological mechanism of the conversion from ADPC to CRPC by exploring the function of lung cancer metastasis-related protein 1 (LCMR1). We found that LCMR1 and glucocorticoid receptor α (GRα) were highly expressed in CRPC tissues, compared to ADPC tissues, and were accompanied by high concentrations of inflammatory factors. Knocking down LCMR1 or GRα in CRPC cells led to inhibition of metastasis and proliferation and induction of apoptosis. The expression of HSP90 and IL-6 was upregulated and that of androgen receptor was downregulated by knocking down LCMR1 or GRα in CRPC cells. Luciferase assay results indicated that the transcription of GRα was promoted by the LCMR1 promoter. The growth rate of CRPC cells in vivo was greatly decreased by knocking down LCMR1 or GRα. Lastly, CRPC cell sensitivity to enzalutamide treatment was found significantly enhanced by the knockdown of LCMR1. Taken together, LCMR1 might regulate the conversion of ADPC to CRPC by activating the GRα signaling pathway.

Minimally disruptive needle insertion: a biologically inspired solution

The mobility of soft tissue can cause inaccurate needle insertions. Particularly in steering applications that employ thin and flexible needles, large deviations can occur between pre-operative images of the patient, from which a procedure is planned, and the intra-operative scene, where a procedure is executed. Although many approaches for reducing tissue motion focus on external constraining or manipulation, little attention has been paid to the way the needle is inserted and actuated within soft tissue. Using our biologically inspired steerable needle, we present a method of reducing the disruptiveness of insertions by mimicking the burrowing mechanism of ovipositing wasps. Internal displacements and strains in three dimensions within a soft tissue phantom are measured at the needle interface, using a scanning laser-based image correlation technique. Compared to a conventional insertion method with an equally sized needle, overall displacements and strains in the needle vicinity are reduced by 30% and 41%, respectively. The results show that, for a given net speed, needle insertion can be made significantly less disruptive with respect to its surroundings by employing our biologically inspired solution. This will have significant impact on both the safety and targeting accuracy of percutaneous interventions along both straight and curved trajectories.

Comparison between preoperative and real-time intraoperative planning ¹²⁵I permanent prostate brachytherapy: long-term clinical biochemical outcome

Background

The purpose of the study is to evaluate the long-term clinical outcome through biochemical no evidence of disease (bNED) rates among men with low to intermediate risk prostate cancer treated with two different brachytherapy implant techniques: preoperative planning (PP) and real-time planning (IoP).

Methods

From June 1998 to July 2011, 1176 men with median age of 67 years and median follow-up of 47 months underwent transperineal ultrasound-guided prostate ¹²⁵I-brachytherapy using either PP (132) or IoP (1044) for clinical T1c-T2b prostate adenocarcinoma Gleason <8 and prostate-specific antigen (PSA) <20 ng/ml. Men with Gleason 7 received combination of brachytherapy, external beam radiation and 6-month androgen deprivation therapy (ADT). Biological effective dose (BED) was calculated using computerized tomography (CT)-based dosimetry 1-month postimplant. Failure was determined according to the Phoenix definition.

Results

The 5- and 7-year actuarial bNED rate was 95% and 90% respectively. The 7-year actuarial bNED was 67% for the PP group and 95% for the IoP group (P < 0.001). Multivariate Cox regression analyses identified implant technique or BED, ADT and PSA as independent prognostic factors for biochemical failure.

Conclusions

Following our previous published results addressing the limited and disappointing outcomes of PP method when compared to IoP based on CT dosimetry and PSA kinetics, we now confirm the long-term clinical, bNED rates clear cut superiority of IoP implant methodology.

Target motion predictions for pre-operative planning during needle-based interventions

During biopsies, breast tissue is subjected to displacement upon needle indentation, puncture, and penetration. Thus, accurate needle placement requires pre-operative predictions of the target motions. In this paper, we used ultrasound elastography measurements to non-invasively predict elastic properties of breast tissue phantoms. These properties were used in finite element (FE) models of indentation of breast soft tissue phantoms. To validate the model predictions of target motion, experimental measurements were carried out. Breast tissue phantoms with cubic and hemispherical geometries were manufactured and included materials with different elastic properties to represent skin, adipose tissue, and lesions. Ultrasound was used to track the displacement of the target (i.e., the simulated lesion) during indentation. The FE model predictions were compared with ultrasound measurements for cases with different boundary conditions and phantom geometry. Maximum errors between measured and predicted target motions were 12% and 3% for the fully supported and partially supported cubic phantoms at 6.0 mm indentation, respectively. Further, FE-based parameter sensitivity analysis indicated that increasing skin elastic modulus and reducing the target depth location increased the target motion. Our results indicate that with a priori knowledge about the geometry, boundary conditions, and linear elastic properties, indentation of breast tissue phantoms can be accurately predicted with FE models. FE models for pre-operative planning in combination with robotic needle insertions, could play a key role in improving lesion targeting for breast biopsies.

Update on prostate brachytherapy: long-term outcomes and treatment-related morbidity

Current research in prostate brachytherapy focuses on five key concepts covered in this review. Transrectal ultrasound-guided prostate brachytherapy assisted by intraoperative treatment planning is the most advanced form of image-guided radiation delivery. Prostate brachytherapy alone for low-risk prostate cancer achieves lower prostate-specific antigen (PSA) nadirs than intensity-modulated radiotherapy (IMRT) or protons while maintaining durable biochemical control in about 90% of patients without late failures seen in surgically treated patients. As an organ-conserving treatment option, seed implant results in a lower rate of erectile dysfunction and urinary incontinence than surgery that has been validated in several recent prospective studies. Combined IMRT and seed implant has emerged as a rational and highly effective approach to radiation-dose escalation for intermediate- and high-risk prostate cancer. Preliminary results suggest that seed implantation may play a role in improving outcomes for historically poor-prognosis locally advanced and recurrent prostate cancers.

Benign prostatic hyperplasia and prostate cancer: an overview for primary care physicians

Benign prostatic hyperplasia (BPH) and prostate cancer (CaP) are major sources of morbidity in older men. Management of these disorders has evolved considerably in recent years. This article provides a focused overview of BPH and CaP management aimed at primary care physicians. Current literature pertaining to BPH and CaP is reviewed and discussed. The management of BPH has been influenced by the adoption of effective medical therapies; nonetheless, surgical intervention remains a valid option for many men. This can be accomplished with well-established standards such as transurethral resection of the prostate or with minimally invasive techniques. Prostate cancer screening remains controversial despite the recent publication of two large clinical trials. Not all prostate cancers necessarily need to be treated. Robot-assisted prostatectomy is a new and increasingly utilised technique for CaP management, although open radical retropubic prostatectomy is the oncological reference standard. The ageing of the population of the developed world means that primary care physicians will see an increasing number of men with BPH and CaP. Close collaboration between primary care physicians and urologists offers the key to successful management of these disorders.

Investigational therapies for brain metastases

Contrary to the incidence of primary cancers, the incidence of brain metastasis has been increasing. This increase is likely because of the effects of an aging population, improved neuroimaging surveillance, and better control of systemic cancer, allowing time for brain metastasis to occur. Unlike systemic cancers, for which chemotherapy is the mainstay of treatment, the therapeutic strategies available to treat brain metastasis have traditionally been limited to surgical resection, whole brain radiation therapy, or stereotactic radiosurgery, either individually or in combination. It is important to put the treatment in the context of the prognosis for patients with brain metastases.