Current status and perspectives of brachytherapy for prostate cancer

Biliary drainage combined with simultaneous 125I seed strand brachytherapy for the treatment of hilar cholangiocarcinoma

BACKGROUND

To evaluate the clinical efficacy of percutaneous biliary drainage (PBD) combined with ¹²⁵I seed strand brachytherapy (ISSB) for the treatment of hilar cholangiocarcinoma (HCCA).

METHODS

The clinical data of 64 patients with HCCA (median age 62.5, male 29, female 35) treated in our department from April 2017 to April 2021 were retrospectively analyzed. Thirty-four patients in the experimental group (EG) were treated with PBD combined with ISSB, while 30 patients in the control group (CG) were treated with PBD alone. The primary study endpoints were technical success, clinical success and the 2-month local tumor control (LTC) rate. Secondary endpoints were early/late complications, median progression-free survival (mPFS) and overall survival (mOS).

RESULTS

The technical and clinical success in the EG and CG showed no significant differences (100 vs. 100%, 94.1 vs. 93.3%, P > 0.05). Both early and late complications showed no significant differences between the two groups (P > 0.05). The 2-month LTC rates were significantly better in the EG versus the CG (94.1% vs. 26.7%, 157.7 ± 115.3 vs. 478.1 ± 235.3 U/ml), respectively (P < 0.05). The mPFS and mOS were 4.3 (95% CI 3.9-4.7) months and 2.8 (95% CI 2.5-3.1) months and 13.5 (95% CI 10.7-16.3) months and 8.8 (95% CI 7.8-9.8) months, respectively, with significant differences (P < 0.05).

CONCLUSION

PBD combined with ISSB is a safe and effective treatment for HCCA that can inhibit local tumors and prolong PFS and OS.

Prostate and dominant intraprostatic lesion segmentation on PET/CT using cascaded regional-net

Focal boost to dominant intraprostatic lesions (DILs) has recently been proposed for prostate radiation therapy. Accurate and fast delineation of the prostate and DILs is thus required during treatment planning. In this paper, we develop a learning-based method using positron emission tomography (PET)/computed tomography (CT) images to automatically segment the prostate and its DILs. To enable end-to-end segmentation, a deep learning-based method, called cascaded regional-Net, is utilized. The first network, referred to as dual attention network, is used to segment the prostate via extracting comprehensive features from both PET and CT images. A second network, referred to as mask scoring regional convolutional neural network (MSR-CNN), is used to segment the DILs from the PET and CT within the prostate region. Scoring strategy is used to diminish the misclassification of the DILs. For DIL segmentation, the proposed cascaded regional-Net uses two steps to remove normal tissue regions, with the first step cropping images based on prostate segmentation and the second step using MSR-CNN to further locate the DILs. The binary masks of DILs and prostates of testing patients are generated on the PET/CT images by the trained model. For evaluation, we retrospectively investigated 49 prostate cancer patients with PET/CT images acquired. The prostate and DILs of each patient were contoured by radiation oncologists and set as the ground truths and targets. We used five-fold cross-validation and a hold-out test to train and evaluate our method. The mean surface distance and DSC values were 0.666 ± 0.696 mm and 0.932 ± 0.059 for the prostate and 0.814 ± 1.002 mm and 0.801 ± 0.178 for the DILs among all 49 patients. The proposed method has shown promise for facilitating prostate and DIL delineation for DIL focal boost prostate radiation therapy.

Catheter position prediction using deep-learning-based multi-atlas registration for high-dose rate prostate brachytherapy

PURPOSE

High-dose-rate (HDR) prostate brachytherapy involves treatment catheter placement, which is currently empirical and physician dependent. The lack of proper catheter placement guidance during the procedure has left the physicians to rely on a heuristic thinking-while-doing technique, which may cause large catheter placement variation and increased plan quality uncertainty. Therefore, the achievable dose distribution could not be quantified prior to the catheter placement. To overcome this challenge, we proposed a learning-based method to provide HDR catheter placement guidance for prostate cancer patients undergoing HDR brachytherapy.

METHODS

The proposed framework consists of deformable registration via registration network (Reg-Net), multi-atlas ranking, and catheter regression. To model the global spatial relationship among multiple organs, binary masks of the prostate and organs-at-risk are transformed into distance maps, which describe the distance of each local voxel to the organ surfaces. For a new patient, the generated distance map is used as fixed image. Reg-Net is utilized to deformably register the distance maps from multi-atlas set to match this patient's distance map and then bring catheter maps from multi-atlas to this patient via spatial transformation. Several criteria, namely prostate volume similarity, multi-organ semantic image similarity, and catheter position criteria (far from the urethra and within the partial prostate), are used for multi-atlas ranking. The top-ranked atlas' deformed catheter positions are selected as the predicted catheter positions for this patient. Finally, catheter regression is used to refine the final catheter positions. A retrospective study on 90 patients with a fivefold cross-validation scheme was used to evaluate the proposed method's feasibility. In order to investigate the impact of plan quality from the predicted catheter pattern, we optimized the source dwell position and time for both the clinical catheter pattern and predicted catheter pattern with the same optimization settings. Comparisons of clinically relevant dose volume histogram (DVH) metrics were completed.

RESULTS

For all patients, on average, both the clinical plan dose and predicted plan dose meet the common dose constraints when prostate dose coverage is kept at V100 = 95%. The plans from the predicted catheter pattern have slightly higher hotspot in terms of V150 by 5.0% and V200 by 2.9% on average. For bladder V75, rectum V75, and urethra V125, the average difference is close to zero, and the range of most patients is within ±1 cc.

CONCLUSION

We developed a new catheter placement prediction method for HDR prostate brachytherapy based on a deep-learning-based multi-atlas registration algorithm. It has great clinical potential since it can provide catheter location estimation prior to catheter placement, which could reduce the dependence on physicians' experience in catheter implantation and improve the quality of prostate HDR treatment plans. This approach merits further clinical evaluation and validation as a method of quality control for HDR prostate brachytherapy.

A planning study of focal dose escalations to multiparametric MRI-defined dominant intraprostatic lesions in prostate proton radiation therapy

OBJECTIVES

The purpose of this study is to investigate the dosimetric effect and clinical impact of delivering a focal radiotherapy boost dose to multiparametric MRI (mp-MRI)-defined dominant intraprostatic lesions (DILs) in prostate cancer using proton therapy.

METHODS

We retrospectively investigated 36 patients with pre-treatment mp-MRI and CT images who were treated using pencil beam scanning (PBS) proton radiation therapy to the whole prostate. DILs were contoured on co-registered mp-MRIs. Simultaneous integrated boost (SIB) plans using intensity-modulated proton therapy (IMPT) were created based on conventional whole-prostate-irradiation for each patient and optimized with additional DIL coverage goals and urethral constraints. DIL dose coverage and organ-at-risk (OAR) sparing were compared between conventional and SIB plans. Tumor control probability (TCP) and normal tissue complication probability (NTCP) were estimated to evaluate the clinical impact of the SIB plans.

RESULTS

Optimized SIB plans significantly escalated the dose to DILs while meeting OAR constraints. SIB plans were able to achieve 125, 150 and 175% of prescription dose coverage in 74, 54 and 17% of 36 patients, respectively. This was modeled to result in an increase in DIL TCP by 7.3-13.3% depending on α / β and DIL risk level.

CONCLUSION

The proposed mp-MRI-guided DIL boost using proton radiation therapy is feasible without violating OAR constraints and demonstrates a potential clinical benefit by improving DIL TCP. This retrospective study suggested the use of IMPT-based DIL SIB may represent a strategy to improve tumor control.

ADVANCES IN KNOWLEDGE

This study investigated the planning of mp-MRI-guided DIL boost in prostate proton radiation therapy and estimated its clinical impact with respect to TCP and NTCP.

Multiparametric MRI-guided dose boost to dominant intraprostatic lesions in CT-based High-dose-rate prostate brachytherapy

OBJECTIVE

The purpose of this study is to investigate the dosimetric feasibility of delivering focal dose to multiparametric (mp) MRI-defined DILs in CT-based high-dose-rate (HDR) prostate brachytherapy with MR/CT registration and estimate its clinical benefit.

METHODS

We retrospectively investigated a total of 17 patients with mp-MRI and CT images acquired pre-treatment and treated by HDR prostate brachytherapy. 21 dominant intraprostatic lesions (DILs) were contoured on mp-MRI and propagated to CT images using a deformable image registration method. A boost plan was created for each patient and optimized on the original needle pattern. In addition, separate plans were generated using a virtually implanted needle around the DIL to mimic mp-MRI guided needle placement. DIL dose coverage and organ-at-rick (OAR) sparing were compared with original plan results. Tumor control probability (TCP) was estimated to further evaluate the clinical impact on the boost plans.

RESULTS

Overall, optimized boost plans significantly escalated dose to DILs while meeting OAR constraints. The addition of mp-MRI guided virtual needles facilitate increased coverage of DIL volumes, achieving a V150 > 90% in 85 % of DILs compared with 57 % of boost plan without an additional needle. Compared with original plan, TCP models estimated improvement in DIL control by 28 % for patients with external-beam treatment and by 8 % for monotherapy patients.

CONCLUSION

With MR/CT registration, the proposed mp-MRI guided DIL boost in CT-based HDR brachytherapy is feasible without violating OAR constraints, and indicates significant clinical benefit in improving TCP of DIL. It may represent a strategy to personalize treatment delivery and improve tumor control.

ADVANCES IN KNOWLEDGE

This study investigated the feasibility of mp-MRI guided DIL boost in HDR prostate brachytherapy with CT-based treatment planning, and estimated its clinical impact by TCP and NTCP estimation.

The combined therapeutic effects of 131iodine-labeled multifunctional copper sulfide-loaded microspheres in treating breast cancer

Compared to conventional cancer treatment, combination therapy based on well-designed nanoscale platforms may offer an opportunity to eliminate tumors and reduce recurrence and metastasis. In this study, we prepared multifunctional microspheres loading 131I-labeled hollow copper sulfide nanoparticles and paclitaxel (131I-HCuSNPs-MS-PTX) for imaging and therapeutics of W256/B breast tumors in rats. 18F-fluordeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) imaging detected that the expansion of the tumor volume was delayed (P<0.05) following intra-tumoral (i.t.) injection with 131I-HCuSNPs-MS-PTX plus near-infrared (NIR) irradiation. The immunohistochemical analysis further confirmed the anti-tumor effect. The single photon emission computed tomography (SPECT)/photoacoustic imaging mediated by 131I-HCuSNPs-MS-PTX demonstrated that microspheres were mainly distributed in the tumors with a relatively low distribution in other organs. Our results revealed that 131I-HCuSNPs-MS-PTX offered combined photothermal, chemo- and radio-therapies, eliminating tumors at a relatively low dose, as well as allowing SPECT/CT and photoacoustic imaging monitoring of distribution of the injected agents non-invasively. The copper sulfide-loaded microspheres, 131I-HCuSNPs-MS-PTX, can serve as a versatile theranostic agent in an orthotopic breast cancer model.

Treating cancerous large airway stenosis with staging radioactive particle implantation guided by computed tomography and fiber bronchoscopy: a clinical study

Background

The purpose of this study is to investigate the clinical effectiveness of staging radioactive particle implantation guided by computed tomography (CT) and fiber–optic bronchoscopy in treating cancerous large airway stenosis.

Methods

A total of 102 patients were included; 57 had undergone staging radioactive particle implantation guided by CT and fiber bronchoscopy and 45 did not. Patients were evaluated by CT and fiber–optic bronchoscopy to determine the feasibility of the implantation of radioactive seeds for the treatment of cancerous large airway stenosis. The treatment planning system (TPS) was used to plan the doses. Radioactive seeds were implanted using fiber–optic bronchoscopy. One week later, CT-guided implantation of radioactive seeds was performed.

Results

The clinical evaluation showed complete, partial, slight, and non-response in 38, 14, 5, and 0 patients, respectively. None of the patients were found with serious complications. The diameter of the affected airway, Karnofsky score, dyspnea index, survival, and quality of life of the patients in both groups was significantly higher and significantly different after the treatment (P < 0.05). The dyspnea index was significantly lower in the treatment group as compared with the control group (P < 0.001).

Conclusion

CT- and fiber bronchoscopy-guided staging radioactive particle implantation has definite treatment effectiveness in treating cancerous large airway stenosis. It should be widely used in clinical practices.

The evolution of brachytherapy for prostate cancer

Brachytherapy (BT), using low-dose-rate (LDR) permanent seed implantation or high-dose-rate (HDR) temporary source implantation, is an acceptable treatment option for select patients with prostate cancer of any risk group. The benefits of HDR-BT over LDR-BT include the ability to use the same source for other cancers, lower operator dependence, and - typically - fewer acute irritative symptoms. By contrast, the benefits of LDR-BT include more favourable scheduling logistics, lower initial capital equipment costs, no need for a shielded room, completion in a single implant, and more robust data from clinical trials. Prospective reports comparing HDR-BT and LDR-BT to each other or to other treatment options (such as external beam radiotherapy (EBRT) or surgery) suggest similar outcomes. The 5-year freedom from biochemical failure rates for patients with low-risk, intermediate-risk, and high-risk disease are >85%, 69-97%, and 63-80%, respectively. Brachytherapy with EBRT (versus brachytherapy alone) is an appropriate approach in select patients with intermediate-risk and high-risk disease. The 10-year rates of overall survival, distant metastasis, and cancer-specific mortality are >85%, <10%, and <5%, respectively. Grade 3-4 toxicities associated with HDR-BT and LDR-BT are rare, at <4% in most series, and quality of life is improved in patients who receive brachytherapy compared with those who undergo surgery.

Excitation function and yield for the 103Rh(d,2n)103Pd nuclear reaction: Optimization of the production of palladium-103

Deuteron-induced nuclear reactions for the generation of ¹⁰³Pd were investigated using the stacked-foil activation technique on rhodium targets at deuteron energies up to E_d=33MeV. The excitation functions of the reactions ¹⁰³Rh(d,xn)^101,103Pd, ¹⁰³Rh(d,x)^{100g,cum,101m,g,102m,g}Rh and ¹⁰³Rh(d,2p)¹⁰³Ru have been measured, and the Thick-Target Yield for ¹⁰³Pd has been calculated.

Theranostic Nanoseeds for Efficacious Internal Radiation Therapy of Unresectable Solid Tumors

Malignant tumors are considered “unresectable” if they are adhere to vital structures or the surgery would cause irreversible damages to the patients. Though a variety of cytotoxic drugs and radiation therapies are currently available in clinical practice to treat such tumor masses, these therapeutic modalities are always associated with substantial side effects. Here, we report an injectable nanoparticle-based internal radiation source that potentially offers more efficacious treatment of unresectable solid tumors without significant adverse side effects. Using a highly efficient incorporation procedure, palladium-103, a brachytherapy radioisotope in clinical practice, was coated to monodispersed hollow gold nanoparticles with a diameter about 120 nm, to form ¹⁰³Pd@Au nanoseeds. The therapeutic efficacy of ¹⁰³Pd@Au nanoseeds were assessed when intratumorally injected into a prostate cancer xenograft model. Five weeks after a single-dose treatment, a significant tumor burden reduction (>80%) was observed without noticeable side effects on the liver, spleen and other organs. Impressively, >95% nanoseeds were retained inside the tumors as monitored by Single Photon Emission Computed Tomography (SPECT) with the gamma emissions of ¹⁰³Pd. These findings show that this nanoseed-based brachytherapy has the potential to provide a theranostic solution to unresectable solid tumors.

Synthetic Approach to Glycopolymer Base Nanoparticle Gold(I) Conjugate: A New Generation of Therapeutic Agents

Advances in nanotechnology have led to the fabrication of nano-constructs of organic or inorganic origins with well-defined structures, surface properties, and can be made to respond to physical or chemical stimuli. These nano-constructs can provide a shift in the way diagnostic and therapeutic drugs are delivered to achieve target specificity and increased retention of therapeutic doses for considerable improvement in the overall treatment of the tumors. In this case we describe here a synthetic approach to glycopolymer base nanoparticle gold(I) conjugate for cancer therapy.

Obstructive component analysis of radioactive stents and common plastic stents in the bile duct

BACKGROUND

Endoscopic placement of a iodine-125 radioactive stent is useful to treat obstructive jaundice with unresectable periampullary tumors. This study aimed to retrospectively evaluate the obstructive component of biliary radioactive stents and discuss the different obstructive mechanism with common plastic stents.

PATIENTS AND METHODS

Twenty consecutive patients with malignant obstruction underwent insertion of stents into the common bile duct, including 10 radioactive stents and 10 polyethylene stents. The radioactive stents were withdrawn after ∼3 months or earlier if clinical signs suggested stent clogging. Polyethylene stents were withdrawn after physical signs suggested stent clogging. Bacteriologic analyses included identification of aerobic and anaerobic bacteria. Stent surfaces were observed by scanning electron microscopy. Stent deposition was identified by Fourier-transformed infrared spectroscopy and pyrolysis derivatization/gas chromatography/mass spectrometry.

RESULTS

Radioactive stent group and polyethylene stent group stents were placed for 86 days (interquartile range 62, 114) and 146 days (interquartile range 105, 181) respectively. The placement duration of the two types of stents was statistically significant. A variety of microorganisms were cultured from the stent deposits. Scanning electron microscope images showed a thicker necrotic layer on the external surface of polyethylene stent than the radioactive stent group. The proportions of obstructive components in each stent were different, but none of them were statistically significant. Necrotic tumor tissue was found in the radioactive stent group.

CONCLUSION

Similar clogging events occurred in both radioactive stents and polyethylene stents. The median duration time of the radioactive stent was shorter, probably because of the smaller inner diameter, and the radioactive seeds exerted no beneficial effect in inhibiting microorganisms.

Combining theoretical potential and advanced technology in high-dose rate brachytherapy boost therapy for prostate cancer

External beam radiation therapy (EBRT) combined with brachytherapy (BT) is an attractive treatment option for select patients with clinically localized prostate cancer. Either low- or high-dose rate BT may be combined with EBRT ('LDR-BT boost,' 'HDR-BT boost,' respectively). HDR-BT boost has potential theoretical benefits over LDR-BT boost or external beam radiation therapy monotherapy in terms of radiobiology, radiophysics and patient convenience. Based on prospective studies in this review, freedom from biochemical failure (FFBF) rates at 5 years for low-, intermediate- and high-risk patients have generally been 85-100%, 68-97%, 63-85%, respectively; late Radiotherapy and Oncology Group Grades 3 and 4 genitourinary and gastrointestinal toxicities are seen in <8% of patients. HDR-BT boost is now a relatively well-established treatment modality for certain intermediate-risk and high-risk prostate cancer patients, though limitations exist in drawing conclusions from the currently published studies.

A gEUD-based inverse planning technique for HDR prostate brachytherapy: feasibility study

PURPOSE

The purpose of this work was to study the feasibility of a new inverse planning technique based on the generalized equivalent uniform dose for image-guided high dose rate (HDR) prostate cancer brachytherapy in comparison to conventional dose-volume based optimization.

METHODS

The quality of 12 clinical HDR brachytherapy implants for prostate utilizing HIPO (Hybrid Inverse Planning Optimization) is compared with alternative plans, which were produced through inverse planning using the generalized equivalent uniform dose (gEUD). All the common dose-volume indices for the prostate and the organs at risk were considered together with radiobiological measures. The clinical effectiveness of the different dose distributions was investigated by comparing dose volume histogram and gEUD evaluators.

RESULTS

Our results demonstrate the feasibility of gEUD-based inverse planning in HDR brachytherapy implants for prostate. A statistically significant decrease in D10 or/and final gEUD values for the organs at risk (urethra, bladder, and rectum) was found while improving dose homogeneity or dose conformity of the target volume.

CONCLUSIONS

Following the promising results of gEUD-based optimization in intensity modulated radiation therapy treatment optimization, as reported in the literature, the implementation of a similar model in HDR brachytherapy treatment plan optimization is suggested by this study. The potential of improved sparing of organs at risk was shown for various gEUD-based optimization parameter protocols, which indicates the ability of this method to adapt to the user's preferences.

Diffusion pattern of low dose rate brachytherapy for prostate cancer in Japan

Permanent implant brachytherapy for prostate cancer using iodine-125 seeds was adopted in Japan in 2003. Here, we report on the diffusion pattern of this treatment in Japan since 2003. We examined the annual numbers of prostate cancer patients per hospital in Japan, who were treated with iodine-125 seed implant brachytherapy with or without external beam radiation therapy between 2003 and 2011. The hospitals were excluded from the count if brachytherapy was begun in a hospital within the given year, and thus was only available for part of the year. In 2004, 269 patients were treated by brachytherapy at only two hospitals. However, the numbers increased rapidly. A total of 1412 patients were treated at 23 hospitals in 2005, 2783 patients were treated at 83 hospitals in 2008, and 3793 patients were treated at 109 hospitals in 2011. The mean/median numbers of patients treated per hospital were 61.4/42 in 2005, 33.5/25 in 2008, and 35.0/24 in 2011. The number of hospitals where 24 or fewer patients were treated in a year increased. On the other hand, the number of hospitals with a volume of >48 patients per year was stable. Because a relationship between provider volume and outcomes following oncological procedures was shown, a careful evaluation of the effectiveness of permanent implant brachytherapy for prostate cancer is needed.

Monte Carlo study of a new I-125 brachytherapy prototype seed with a ceramic radionuclide carrier and radiographic marker

In prostate cancer treatment, there is an increasing interest in the permanent radioactive seeds implant technique. Currently, in Brazil, the seeds are imported with high prices, which prohibit their use in public hospitals. A ceramic matrix that can be used as a radioisotope carrier and radiographic marker was developed at our institution. The ceramic matrix is distinguished by the characteristic of maintaining the radioactive material uniformly distributed in its surface. In this work, Monte Carlo simulations were performed in order to assess the dose distributions generated by this prototype seed model, with the ceramic matrix encapsulated in titanium, in the same way as the commercial 6711 seed. The obtained data was assessed, as described in the TG-43U1 report by the American Association of Physicists in Medicine, for two seed models: (1) the most used model 6711 source - for validation and comparison, and (2) for the prototype model with the ceramic matrix. The dosimetric parameters dose rate constant, Λ, radial dose function, gL(r), and anisotropy function, F(r,θ), were derived from simulations by the Monte Carlo method using the MCNP5 code. A Λ 0.992 (± 2.33%) cGyh-1U-1 was found for the prototype model. In comparison with the 6711 model, a lower dose fall-off on transverse axis was found, as well as a lower dose anisotropy for the radius r = 0.25 cm. In general, for all distances, the prototype seed model presents a slightly larger anisotropy between 0° ≤ Θ < 50° and anisotropy similar to the 6711 model for Θ ≥ 50°. The dosimetric characteristics of the prototype model presented in this study suggest that its use is feasible. Because of the model's characteristics, seeds of lower specific activity iodine might be necessary which, on the other hand, would help to reduce costs. However, it has to be emphasized that the proposed source is a prototype, and the required (AAPM prerequisites) experimental study and tolerance manufacturer values are pending for future studies.

Prostate cancer overview

OBJECTIVES

To review prostate anatomy, epidemiology and risk factors, presentation and diagnosis, staging and treatment, emerging therapies, and patient education.

DATA SOURCES

Review of current and classic literature.

CONCLUSION

Patients must be educated regarding screening recommendations and offered evidence-based guidance regarding the risks, benefits, and alternatives to treatment. Adverse effects of treatment may impact quality of life.

IMPLICATIONS FOR NURSING PRACTICE

As the incidence of prostate cancer continues to rise, nurses will play an essential role in the treatment and counseling of men facing this malignancy. Nursing research will also be necessary to further investigate quality-of-life concerns and evidence-based practice regarding symptom management.

An overview of prostate diseases and their characteristics specific to Asian men

In this paper, we reviewed the features of common prostate diseases, such as benign prostatic hyperplasia (BPH), prostate cancer (PCa) and chronic prostatitis (CP) that are specific to Asian men. Compared to the Westerners, Asians exhibit particular characteristics of prostate diseases. Through summarizing the epidemiology, symptomatology, diagnostics and therapeutics of these diseases, we find that Asians have a lower incidence of PCa than whites, but the incidences of BPH and CP are similar. Asian men with CP often suffer from fewer disease sites, but have a higher frequency of pain during urination rather than after sexual climax. Prostate-specific antigen (PSA) is a widely used marker for the diagnosis of PCa in both Asian and Western countries. Although the PSA level may be lower in Asians, the threshold used is based on whites. After reviewing the treatments available for these diseases, we did not find a fundamental difference between Asians and whites. Furthermore, the selection for the most appropriate treatment based on the individual needs of patients remains a challenge to urologists in Asia. After considering the traits of prostate diseases that are specific to Asian men, we hope to pave the way for the development of specific diagnostic and therapeutic strategies targeted specifically to Asian men.

Short-term outcomes of CyberKnife therapy for advanced high-risk tumors: A report of 160 cases

The objective of the present study was to evaluate short-term outcomes of CyberKnife therapy in patients with advanced high-risk tumors. A total of 201 target areas from 341 advanced high-risk tumor lesions in 160 patients were treated with CyberKnife. A prescribed dose of 18-60 Gy to the gross tumor volume was delivered in 1-6 fractions to complete the entire treatment in 1 week. Radiographic studies and clinical examinations were performed at 1- to 3-month follow-up intervals, and the results were compared to outcomes of 160 similar advanced high-risk tumor patients who were treated by conformal radiotherapy (CRT). After CyberKnife therapy, the short-term improvement in the quality of life was significant according to radiographic study, radioimmunoassay and ZPS scores of these patients. The total rates of objective efficacy and alleviation of ascities were as high as 66.88 and 67.90%. The short-term outcomes in our series of patients with advanced high-risk tumors treated with CyberKnife appeared to be better compared to conventional CRT. CyberKnife may be an option for patients with incurable advanced high-risk tumors, although further studies of the long-term outcomes are required to confirm the validity.

Dose measurement for medical staff with glass dosemeters and thermoluminescence dosemeters during 125I brachytherapy for prostate cancer

Photoluminescence glass dosemeters (PLDs) and thermoluminescence dosemeters (TLDs) are commonly used as a personal monitoring dosemeter. PLDs and TLDs were used for surface dose monitoring of medical staff involved in (125)I brachytherapy for prostate cancer because these dosemeters have a wide dose-response linearity and high sensitivity for low photon energy. Surface doses measured with PLDs agreed with those with TLDs within ∼20 % except for a few cases. Surface doses at a surgeon's left hand and arm were higher than those at the other measuring points. A surgeon received a maximum dose of 650 μGy at the back of left hand. Surface doses to an assistant were <100 μGy. Surface doses to a nurse, a radiologist, an anaesthesiologist and a radiological technologist were <10 μGy. The occupational exposure to a surgeon could be reduced by the adjustment of fluoroscopic parameters and the use of lead gloves.

HDR monotherapy for prostate cancer: a simulation study to determine the effect of catheter displacement on target coverage and normal tissue irradiation

PURPOSE

The aim of this study was to systematically analyse the effect of catheter displacements both on target coverage and normal tissue irradiation in fractionated high dose rate (HDR) prostate brachytherapy, using a simulation study, and to define tolerances for catheter displacement ensuring that both target coverage and normal tissue doses remain clinically acceptable. Besides the effect of total implant displacement, also displacements of catheters belonging to selected template rows only were evaluated in terms of target coverage and normal tissue dose, in order to analyse the change in dose distribution as a function of catheter dwell weight and catheter location.

MATERIAL AND METHODS

Five representative implant geometries, with 17 catheters each, were selected. The clinical treatment plan was compared to treatment plans in which an entire implant displacement in caudal direction over 3, 5, 7 and 10 mm was simulated. Besides, treatment plans were simulated considering a displacement of either the central, most ventral or most dorsal catheter rows only, over 5 mm caudally.

RESULTS

Due to displacement of the entire implant the target coverage drops below the tolerance of 93% for all displacements studied. The effect of displacement of the entire implant on organs at risk strongly depended on the patient anatomy; e.g., for 80% of the implant geometries the V(80) of the rectum exceeded its tolerance for all displacements. The effect of displacement of catheters belonging to selected template rows depended strongly on the relative weight of each catheter row when considering the target coverage and on its location when considering the dose in the organs at risk.

CONCLUSION

This study supports the need for a check of the catheter locations before each fraction and correction of deviations of the catheter position exceeding 3mm.

The experiences of unpartnered men with prostate cancer: a qualitative analysis

PURPOSE

The purpose of this study was to examine how men without partners make decisions about prostate cancer treatment, manage treatment side effects, and obtain information and support.

BACKGROUND

In 2009, it was projected that over 230,000 men were diagnosed with prostate cancer. While treatment options vary, these options result in changes within the man that can affect his quality of life. Research has shown that often spouses play a central role in men's choice of treatment and in maintaining men's quality of life. In addition, spouses are the major providers of emotional support and physical care. However, little is known about how men without partners cope with prostate cancer. Prior research seldom addresses how diagnosis and treatment for prostate cancer affects the quality of life of men without partners.

METHODS

Because very little is known about the needs of men without partners managing prostate cancer, qualitative analysis of data obtained during semi-structure interviews provided respondents with an opportunity to share the lived experience of prostate cancer. A semi-structured interview was conducted with selected, consenting men. The sample was drawn from the ongoing R01 study of men with prostate cancer (PROSTQA).

RESULTS

The sample for this study included 17 unpartnered prostate cancer survivors. The ages of participants ranged from 47 to 72 with a mean age of 63. The participants had between zero and two co-morbidities with an average of one co-morbidity per participant. The sample was 82% Caucasian and 17% Black. A total of 35% of the participants reported "some college" (n  =  6), 30% graduated from college (n  =  5), and 23% went to graduate school (n  =  4). One participant reported that he was a high school graduate and one had less than a high school education. Five themes emerged from the data: going it alone, diagnosis and prostate cancer treatment decision-making, sources of information and support, the aftermath of prostate cancer, and coping strategies.

CONCLUSIONS

This study provides information about unpartnered men's prostate cancer experience. This information will help health care professionals to meet the needs of unpartnered more effectively and help them to assist men as they adapt to living with this chronic illness.

Verification of air-kerma strength of 125I seed for permanent prostate implants in Japan

BACKGROUND

To assure the physical quality of brachytherapy, we investigated the difference between measured and manufacturer's stated source strengths in a single model SourceTech Medical (STM)1251 (125)I seed.

METHODS

A well-type ionization chamber with a single-seed holder was used to measure the source strength of 2412 (125)I seeds before implant in 34 patients. The air-kerma strength was 0.450 U for all cases. The mean source strength for each patient was measured and compared with the manufacturer's stated value. The deviation from the measured value was compared with the tolerance range of the American Association of Physicists in Medicine (AAPM) TG-56 report's recommendation.

RESULTS

The measured source strength was higher than the manufacturer's stated value, with a median difference of 1% (range, 2% to 5%). Sixteen of the total of 2412 seeds (0.7%) were more than 5% different from the manufacturer's stated value. The median SD from the mean value was 2.2% (range, 1.1% to 2.5%) for all patients.

CONCLUSION

This is the first report of a single-seed assay performed for the model STM1251 (125)I seed. In this study the manufacturer's stated strength agreed well with the measured value. Nevertheless, the advisability of performing a single-seed assay at every institution should be considered, by referring to the appropriate regulations; for example, those used in the United States.