Management of prostate cancer recurrence after definitive radiation therapy

Oncological control in high-risk prostate cancer after radical prostatectomy and salvage radiotherapy compared to radiotherapy plus primary hormone therapy

INTRODUCTION

In patients with high-risk localized prostate cancer (HRPCa), multimodal treatment plays a fundamental role.

OBJECTIVE

To compare relapse-free survival (RFS) in patients with HRPCa, treated primarily with radiotherapy (RT)+hormone therapy (HT) versus radical prostatectomy (RP) and salvage RT (sRT)±HT when biochemical recurrence (BCR) appears.

MATERIAL AND METHODS

Retrospective analysis of 226 patients with HRPCa (1996-2008), treated primarily with RT+HT (n=137) or RP (n=89). The Kaplan-Meier method has been used to evaluate survival and the log-rank test has been used to evaluate the contrast between the different categories of the variables. Multivariate analysis has been performed using Cox regression to determine variables with an impact on RFS with statistical significance (P<0.05).

RESULTS

The median follow-up of the series was 111 (IQR 85-137.5) months. After RT+HT, 32 (23.4%) patients relapsed, and after RP (P=0.0001), 41 (46.1%) cases. When comparing the primary treatments, the RFS at 5 and 10 years was higher after RT+HT versus RP in monotherapy (P=0.001). The primary treatment with RT+HT reduced the risk of BCR when compared to the RP (HR=0.41, P=0.002). The estimation of the RFS at 5 and 10 years after RP+sRT±HT was 89.7 and 87.1%, while after primary RT+HT was 91.6 and 71.1%, respectively (P=0.01). The only factor that behaved as an independent predictor of RFS was the multimodal treatment with RP+sRT±HT when BCR showed up (HR=2.39, P=0.01).

CONCLUSION

In HRPCa, multimodal treatment with RP+sRT±HT if BCR, significantly improves RFS with respect to treatment with RT+HT.

Focal Salvage High Dose-Rate Brachytherapy for Locally Recurrent Prostate Cancer After Primary Radiation Therapy Failure: Results From a Prospective Clinical Trial

PURPOSE

Although increasing data support whole-gland salvage therapy for recurrent prostate cancer, toxicity remains a significant concern. We hypothesized that focal therapy, treating only a portion of the prostate containing recurrent disease, might be equally effective and associated with less toxicity. The objectives of this prospective study were to explore the toxicities, quality of life, and efficacy of focal salvage high-dose-rate (HDR) brachytherapy in patients with multiparametric magnetic resonance imaging (MRI)-visible, biopsy-confirmed local recurrence after previous definitive external beam radiation therapy.

MATERIALS AND METHODS

Fifteen patients with locally recurrent prostate cancer after external beam radiation therapy were enrolled in this prospective study. Patients were treated with ultrasound-based HDR brachytherapy with a prescription dose of 27 Gy divided in 2 implants, separated by 1 week, to the clinical target volume, which was defined as the quadrant of the prostate where the MRI-visible recurrent lesion was located. Toxicity, quality of life, and biochemical outcomes were analyzed. Postsalvage MRI was performed to assess radiation therapy response.

RESULTS

Median follow-up was 36 months. The median size of the recurrence on MRI was 9 mm (range, 7-20 mm), and clinical target volume at the time of HDR was 6.1 mL (range, 2.2-16.1 mL). Only one grade 3 genitourinary toxicity event was observed. No urinary retention was observed. Three-year prostate-specific antigen failure-free rate was 61%. There was no significant change in Expanded Prostate Cancer Index Composite urinary or bowel domains over time. Of the 14 patients who had a post-HDR MRI, 12 had a treatment response.

CONCLUSIONS

Our results suggest that focal salvage HDR brachytherapy is well tolerated and promising. External validation is needed.

Phenotypic appearances of prostate utilizing PET-MRI and PET-CT with 68Ga-PSMA, radiolabelled choline and 68Ga-DOTATATE

The objective of this study was to highlight the role of multimodality imaging and present the differential diagnosis of abnormal tracer accumulation in the prostate and periprostatic tissue. Our departments have performed molecular imaging of the prostate utilizing PET-CT and PET-MRI with a range of biomarkers including F-FDG, radiolabelled choline, Ga-DOTATATE PET-CT and Ga-PSMA images. We retrospectively reviewed the varying appearances of the prostate gland in different diseases and incidental findings in periprostatic region. The differential diagnosis of pathologies related to prostate and periprostatic tissue on multimodality imaging includes malakoplakia, rhabdomyosarcoma, lymphoma, prostate cancer, neuroendocrine tumours, uchida changes, rectoprostatic fistula, synchronous malignancies, lymphocoele and schwanoma. There exists a wide differential for abnormal tracer accumulation in the prostate gland. As a radiologist and nuclear medicine physician, it is important to be aware of range of prostatic and periprostatic pathologies.

Brachytherapy for prostate cancer: Present and future

Based on recent, important publications on the impact of brachytherapy in the management of prostate cancer, we analysed already validated indications and the "under investigations" use of brachytherapy. Published studies (MEDLINE), randomized trials and recommendations were reviewed, as well as Delphi consensus when available. While low-dose rate brachytherapy remains a standard of care for low-risk eligible patients, three randomized trials are now available to consider that combination of external beam radiation therapy with brachytherapy boost (low- or high-dose rate) appears as a recommended treatment for intermediate and high-risk patients. Other indications of prostate brachytherapy (monotherapy and salvage) remain under evaluation. For low-risk patients with good urinary status, low-dose rate brachytherapy alone should be offered. For low-intermediate risk prostate cancer, low-dose rate brachytherapy alone may be offered as monotherapy, while for high-intermediate risk prostate cancer, a combination of external beam radiation therapy (with or without androgen deprivation therapy) plus brachytherapy boost (low- or high-dose rate) should be offered to eligible patients. For patients with high-risk prostate cancer receiving external beam radiation therapy and androgen deprivation therapy, brachytherapy boost (low- or high-dose rate) should be offered to eligible patients. High-dose rate brachytherapy as monotherapy (single dose for low-risk/multifractionated for intermediate and high-risk) must be explored under clinical investigations, as well as salvage brachytherapy for local recurrence.

Salvage prostate re-irradiation using high-dose-rate brachytherapy or focal stereotactic body radiotherapy for local recurrence after definitive radiation therapy

Background

Optimal management of locally recurrent prostate cancer after definitive radiation therapy is still challenging. With the development of highly accurate radiotherapy devices, prostate salvage re-irradiation might generate lower toxicity rates than classical salvage therapies. We retrospectively evaluated the toxicity and the feasibility of a prostate re-irradiation after definitive radiation therapy failure. Two modalities were investigated: high-dose-rate brachytherapy (HDRB) on whole prostate gland and focal stereotactic radiotherapy (SBRT) using CyberKnife® linac.

Methods

Between 2011 and 2015, 28 patients with imaged and/or biopsy-proven intra-prostatic recurrence of cancer after definitive radiation therapy underwent a salvage re-irradiation using HDRB (n = 10) or focal SBRT (n = 18). The schedule of re-irradiation was 35 Gy in 5 fractions.

Biological response (defined as post-salvage radiation PSA variation) and biochemical no-evidence of disease (bNED) were evaluated in the whole cohort. For patients who had a positive biological response after salvage radiation, biochemical recurrence (BCR) and survival after salvage radiotherapy were evaluated. Post-salvage toxicities were assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.03 and were compared to baseline status.

Results

Within a median follow-up of 22.5 months (IQR = 8–42), 9 (90%) patients experienced a positive biological response after salvage HDRB and 5 (50%) remained bNED at the end of the follow-up. Among patients who initially responded to salvage HDRB, the BCR rate was 44.4% after a median interval of 19.5 months (IQR = 11.5–26). Only one patient experienced a transient grade 3 urinary complication.

In the SBRT group, the median follow-up was 14.5 months (IQR = 7–23) and 10 (55.6%) out of the 18 patients remained bNED. Among the 15 patients who initially responded to salvage SBRT, 5 (33.3%) experienced a BCR. One patient experienced a transient grade 4 urinary complication.

At the end of the follow-up, all evaluated patients had a urinary status grade variation ≤ +1 grade. No grade 3–4 digestive toxicity was observed.

Conclusions

Salvage prostate re-irradiation for locally recurrent cancer is feasible and generate low toxicities rates when using with HDRB or focal SBRT. However, further investigations are necessary to confirm these findings and to determine predictive features for patients who might benefit from such an approach.

Dosimetric feasibility of ablative dose escalated focal monotherapy with MRI-guided high-dose-rate (HDR) brachytherapy for prostate cancer

PURPOSE

To determine the dosimetric feasibility of dose-escalated MRI-guided high-dose-rate brachytherapy (HDR-BT) focal monotherapy for prostate cancer (PCa).

METHODS

In all patients, GTV was defined with mpMRI, and deformably registered onto post-catheter insertion planning MRI. PTV included the GTV plus 9mm craniocaudal and 5mm in every other direction. In discovery-cohort, plans were obtained for each PTV independently aiming to deliver ⩾16.5Gy/fraction (two fraction schedule) while respecting predefined organs-at-risk (OAR) constraints or halted when achieved equivalent single-dose plan (24Gy). Dosimetric results of original and focal HDR-BT plans were evaluated to develop a planning protocol for the validation-cohort.

RESULTS

In discovery-cohort (20-patients, 32-GTVs): PTV D95% ⩾16.5Gy could not be reached in a single plan (3%) and was accomplished (range 16.5-23.8Gy) in 15 GTVs (47%). Single-dose schedule was feasible in 16 (50%) plans. In the validation-cohort (10-patients, 10-GTVs, two separate implants each): plans met acceptable and ideal criteria in 100% and 43-100% respectively. Migration to single-dose treatment schedule was feasible in 7 implants (35%), without relaxing OAR's constraints or increasing the dose (D100% and D35%) to mpMRI-normal prostate (p>0.05).

CONCLUSION

Focal ablative dose-escalated radiation is feasible with the proposed protocol. Prospective studies are warranted to determine the clinical outcomes.

Percutaneous irreversible electroporation (IRE) of prostate cancer: Contrast-enhanced ultrasound (CEUS) findings

PURPOSE

To evaluate the use of contrast-enhanced ultrasound (CEUS) after irreversible electroporation (IRE) of prostatic cancer tissue to assess the ablation status by depicting microvascularisation in the ablation area.

MATERIALS AND METHODS

Retrospective evaluation of CEUS of 13 patients (mean age: 61.4 ± 7.5 years) with histologically confirmed prostatic cancer who underwent percutaneous IRE. In the course of clinical routine, the tumor lesions were documented before, immediately after, and 1 day after the ablationusing color-coded transabdominal and transrectal CEUS. The obtained image data (DICOM loops and images) were subsequently evaluated by 2 experienced radiologists and assessed with regard to micro vascularisation by means of a 5-point scale.

RESULTS

CEUS images showed significantly reduced microcirculation of the lesions (mean 0.9 ± 0.6 cm (0.5-1.5 cm) after IRE. Microcirculation was reduced from 2.15 ± 0.56 prior to ablation to 0.65 ± 0.63 (p <  0.001) immediately after the ablation and to 0.27 ± 0.44 one day after IRE (p <  0.001).

CONCLUSION

This study showed rapid and significant reduction of the microcirculation in the ablation area afterpercutaneous IRE of prostatic cancer tissue.

Recurrent prostate cancer detection with anti-3-[(18)F]FACBC PET/CT: comparison with CT

PURPOSE

To compare the diagnostic performance of the synthetic amino acid analogue PET radiotracer anti-3-[(18)F]FACBC (fluciclovine) with that of CT in the detection of recurrent prostate carcinoma.

METHODS

This was a retrospective analysis of 53 bone scan-negative patients with suspected recurrent prostate carcinoma who underwent fluciclovine PET/CT and routine clinical CT within 90 days of each other. The correlation between imaging findings and histology and clinical follow-up was evaluated. Positivity rates and diagnostic performance were calculated for fluciclovine PET/CT and CT.

RESULTS

Of 53 fluciclovine PET/CT and 53 CT examinations, 41 (77.4 %) and 10 (18.9 %), respectively, had positive findings for recurrent disease. Positivity rates were higher with fluciclovine PET/CT than with CT at all prostate-specific antigen (PSA) levels, PSA doubling times and original Gleason scores. In the prostate/bed, fluciclovine PET/CT was true-positive in 31 and CT was true-positive in 4 of 51 patients who met the reference standard. In extraprostatic regions, fluciclovine PET/CT was true-positive in 12 and CT was true-positive in 3 of 41 patients who met the reference standard. Of the 43 index lesions used to prove positivity, 42 (97.7 %) had histological proof. In 51 patients with sufficient follow-up to calculate diagnostic performance in the prostate/bed, fluciclovine PET/CT demonstrated a sensitivity of 88.6 %, a specificity of 56.3 %, an accuracy of 78.4 %, a positive predictive value (PPV) of 81.6 %, and a negative predictive value (NPV) of 69.2 %; the respective values for CT were 11.4 %, 87.5 %, 35.3 %, 66.7 % and 31.1 %. In 41 patients with sufficient follow-up to calculate diagnostic performance in extraprostatic regions, fluciclovine PET/CT demonstrated a sensitivity of 46.2 %, a specificity of 100 %, an accuracy of 65.9 %, a PPV of 100 %, and an NPV of 51.7 %; the respective values for CT were 11.5 %, 100 %, 43.9 %, 100 % and 39.5 %.

CONCLUSION

The diagnostic performance of fluciclovine PET/CT in recurrent prostate cancer is superior to that of CT and fluciclovine PET/CT provides better delineation of prostatic from extraprostatic recurrence.

Mechanisms of growth inhibition of primary prostate epithelial cells following gamma irradiation or photodynamic therapy include senescence, necrosis, and autophagy, but not apoptosis

In comparison to more differentiated cells, prostate cancer stem-like cells are radioresistant, which could explain radio-recurrent prostate cancer. Improvement of radiotherapeutic efficacy may therefore require combination therapy. We have investigated the consequences of treating primary prostate epithelial cells with gamma irradiation and photodynamic therapy (PDT), both of which act through production of reactive oxygen species (ROS). Primary prostate epithelial cells were cultured from patient samples of benign prostatic hyperplasia and prostate cancer prior to treatment with PDT or gamma irradiation. Cell viability was measured using MTT and alamar blue assay, and cell recovery by colony-forming assays. Immunofluorescence of gamma-H2AX foci was used to quantify DNA damage, and autophagy and apoptosis were assessed using Western blots. Necrosis and senescence were measured by propidium iodide staining and beta-galactosidase staining, respectively. Both PDT and gamma irradiation reduced the colony-forming ability of primary prostate epithelial cells. PDT reduced the viability of all types of cells in the cultures, including stem-like cells and more differentiated cells. PDT induced necrosis and autophagy, whereas gamma irradiation induced senescence, but neither treatment induced apoptosis. PDT and gamma irradiation therefore inhibit cell growth by different mechanisms. We suggest these treatments would be suitable for use in combination as sequential treatments against prostate cancer.

In vivo characterization and numerical simulation of prostate properties for non-thermal irreversible electroporation ablation

BACKGROUND

Irreversible electroporation (IRE) delivers brief electric pulses to attain non-thermal focal ablation that spares vasculature and other sensitive systems. It is a promising prostate cancer treatment due to sparing of the tissues associated with morbidity risk from conventional therapies. IRE effects depend on electric field strength and tissue properties. These characteristics are organ-dependent, affecting IRE treatment outcomes. This study characterizes the relevant properties to improve treatment planning and outcome predictions for IRE prostate cancer treatment.

METHODS

Clinically relevant IRE pulse protocols were delivered to a healthy canine and two human cancerous prostates while measuring electrical parameters to determine tissue characteristics for predictive treatment simulations. Prostates were resected 5 hr, 3 weeks, and 4 weeks post-IRE. Lesions were correlated with numerical simulations to determine an effective prostate lethal IRE electric field threshold.

RESULTS

Lesions were produced in all subjects. Tissue electrical conductivity increased from 0.284 to 0.927 S/m due to IRE pulses. Numerical simulations show an average effective prostate electric field threshold of 1072 ± 119 V/cm, significantly higher than previously characterized tissues. Histological findings in the human cases show instances of complete tissue necrosis centrally with variable tissue effects beyond the margin.

CONCLUSIONS

Preliminary experimental IRE trials safely ablated healthy canine and cancerous human prostates, as examined in the short- and medium-term. IRE-relevant prostate properties are now experimentally and numerically defined. Importantly, the electric field required to kill healthy prostate tissue is substantially higher than previously characterized tissues. These findings can be applied to optimize IRE prostate cancer treatment protocols.

Kallikreins as biomarkers for prostate cancer

The introduction of testing for prostate-specific antigen (PSA), a member of the fifteen-gene family of kallikrein-related peptidases and also known as kallikrein-related peptidase 3 (KLK3), in blood has revolutionized both the detection and management of prostate cancer. Given the similarities between PSA and other KLK gene family members along with limitations of PSA as a biomarker for prostate cancer mainly in reference to diagnostic specificity, the potential roles of other members of this gene family as well as PSA derivatives and isoforms in the management of prostate cancer have been studied extensively. Of these, approaches to measure distinct molecular forms of PSA (free, intact, complexed PSA, and pro-PSA) combined with kallikrein-related peptidase 2 (KLK2), also known as hK2, have been considered holding particular promise in enhancing the diagnosis of prostate cancer. Recently, an integrated approach of applying a panel of four kallikrein markers has been demonstrated to enhance accuracy in predicting the risk of prostate cancer at biopsy. This review presents an overview of kallikreins, starting with the past and current status of PSA, summarizing published data on the evaluations of various KLKs as biomarkers in the diagnosis, prognostication, and monitoring of prostate cancer.

Focal low-dose rate brachytherapy for the treatment of prostate cancer

Whole-gland low-dose rate (LDR) brachytherapy has been a well-established modality of treating low-risk prostate cancer. Treatment in a focal manner has the advantages of reduced toxicity to surrounding organs. Focal treatment using LDR brachytherapy has been relatively unexplored, but it may offer advantages over other modalities that have established experiences with a focal approach. This is particularly true as prostate cancer is being detected at an earlier and more localized stage with the advent of better detection methods and newer imaging modalities.

The dilemma of a rising prostate-specific antigen level after local therapy: what are our options?

Prostate cancer is the most common solid tumor diagnosed in men in the United States and Western Europe. Primary treatment with radiation or surgery is largely successful at controlling localized disease. However, a significant number (up to one third of men) may develop biochemical recurrence (BR), defined as a rise in serum prostate-specific antigen (PSA) level. A general presumption is that BR will lead to overt progression in patients over subsequent years. There are a number of factors that a physician must consider when counseling and recommending treatment to a patient with a rising PSA. These include the following (1) various PSA-based definitions of BR; (2) source of PSA (ie, local or distant disease, residual benign prostate); (3) available modalities to treat the disease with the least morbidity; and (4) timing of therapy. In this article we review the current and future factors that clinicians should consider in the diagnosis and treatment of recurrent prostate cancer.

The effects of metallic implants on electroporation therapies: feasibility of irreversible electroporation for brachytherapy salvage

PURPOSE

Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments.

MATERIALS AND METHODS

This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions.

RESULTS

There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins.

CONCLUSION

This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

Analysis of intraprostatic therapeutic effects in prostate cancer patients using [(11)C]-choline pet/ct after external-beam radiation therapy

PURPOSE

The objective of the present study was to analyze, with relatively high sensitivity and specificity, uptake properties of [(11)C]-choline in prostate cancer patients by means of positron-emission tomography (pet)/computed tomography (ct) imaging using objectively defined pet parameters to test for statistically significant changes before, during, and after external-beam radiation therapy (ebrt) and to identify the time points at which the changes occur.

METHODS

The study enrolled 11 patients with intermediate-risk prostate cancer treated with ebrt, who were followed for up to 12 months after ebrt. The [(11)C]-choline pet scans were performed before treatment (baseline); at weeks 4 and 8 of ebrt; and at 1, 2, 3, 6, and 12 months after ebrt.

RESULTS

Analysis of [(11)C]-choline uptake in prostate tissue before treatment resulted in a maximum standardized uptake value (suvmax) of 4.0 ± 0.4 (n = 11) at 40 minutes after injection. During week 8 of ebrt, the suvmax declined to 2.9 ± 0.1 (n = 10, p < 0.05). At 2 and 12 months after ebrt, suvmax values were 2.3 ± 0.3 (n = 10, p < 0.01) and 2.2 ± 0.2 (n = 11, p < 0.001) respectively, indicating that, after ebrt, maximum radiotracer uptake in the prostate was significantly reduced. Similar effects were observed when analyzing the tumour:muscle ratio (tmr). The tmr declined from 7.4 ± 0.6 (n = 11) before ebrt to 6.1 ± 0.4 (n = 11, nonsignificant) during week 8 of ebrt, to 5.6 ± 0.03 (n = 11, p < 0.05) at 2 months after ebrt, and to 4.4 ± 0.4 (n = 11, p < 0.001) at 12 months after ebrt.

CONCLUSIONS

Our study demonstrated that intraprostatic [(11)C]-choline uptake in the 11 analyzed prostate cancer patients significantly declined during and after ebrt. The pet parameters SUVmax and tmr also declined significantly. These effects can be detected during radiation therapy and up to 1 year after therapy. The prognostic value of these early and statistically significant changes in intraprostatic [(11)C]-choline pet avidity during and after ebrt are not yet established. Future studies are indicated to correlate changes in [(11)C]-choline uptake parameters with long-term biochemical recurrence to further evaluate [(11)C]-choline pet changes as a possible, but currently unproven, biomarker of response.

Multiparametric prostate MR imaging with T2-weighted, diffusion-weighted, and dynamic contrast-enhanced sequences: are all pulse sequences necessary to detect locally recurrent prostate cancer after radiation therapy?

PURPOSE

To compare diagnostic accuracy of T2-weighted magnetic resonance (MR) imaging with that of multiparametric (MP) MR imaging combining T2-weighted imaging with diffusion-weighted (DW) MR imaging, dynamic contrast material-enhanced (DCE) MR imaging, or both in the detection of locally recurrent prostate cancer (PCa) after radiation therapy (RT).

MATERIALS AND METHODS

This retrospective HIPAA-compliant study was approved by the institutional review board; informed consent was waived. Fifty-three men (median age, 70 years) suspected of having post-RT recurrence of PCa underwent MP MR imaging, including DW and DCE sequences, within 6 months after biopsy. Two readers independently evaluated the likelihood of PCa with a five-point scale for T2-weighted imaging alone, T2-weighted imaging with DW imaging, T2-weighted imaging with DCE imaging, and T2-weighted imaging with DW and DCE imaging, with at least a 4-week interval between evaluations. Areas under the receiver operating characteristic curve (AUC) were calculated. Interreader agreement was assessed, and quantitative parameters (apparent diffusion coefficient [ADC], volume transfer constant [K(trans)], and rate constant [k(ep)]) were assessed at sextant- and patient-based levels with generalized estimating equations and the Wilcoxon rank sum test, respectively.

RESULTS

At biopsy, recurrence was present in 35 (66%) of 53 patients. In detection of recurrent PCa, T2-weighted imaging with DW imaging yielded higher AUCs (reader 1, 0.79-0.86; reader 2, 0.75-0.81) than T2-weighted imaging alone (reader 1, 0.63-0.67; reader 2, 0.46-0.49 [P ≤ .014 for all]). DCE sequences did not contribute significant incremental value to T2-weighted imaging with DW imaging (reader 1, P > .99; reader 2, P = .35). Interreader agreement was higher for combinations of MP MR imaging than for T2-weighted imaging alone (κ = 0.34-0.63 vs κ = 0.17-0.20). Medians of quantitative parameters differed significantly (P < .0001 to P = .0233) between benign tissue and PCa (ADC, 1.64 × 10(-3) mm(2)/sec vs 1.13 × 10(-3) mm(2)/sec; K(trans), 0.16 min(-1) vs 0.33 min(-1); k(ep), 0.36 min(-1) vs 0.62 min(-1)).

CONCLUSION

MP MR imaging has greater accuracy in the detection of recurrent PCa after RT than T2-weighted imaging alone, with no additional benefit if DCE is added to T2-weighted imaging and DW imaging.

Diffusion-weighted MRI for locally recurrent prostate cancer after external beam radiotherapy

OBJECTIVE

The objectives of our study were to establish the apparent diffusion coefficients (ADCs) of tumor and nontumor irradiated tissues in patients with suspected postradiation recurrence of prostate cancer and to determine the sensitivity and specificity of a combination of T2-weighted and diffusion-weighted imaging (DWI) for detecting local recurrence.

MATERIALS AND METHODS

Twenty-four patients with rising prostate-specific antigen levels after having completed radiation therapy 30-130 months earlier (median, 62 months) underwent endorectal T2-weighted imaging and DWI (b = 0, 100, 300, 500, and 800 s/mm(2)) followed by transrectal ultrasound (TRUS)-guided biopsy. Images were scored prospectively as positive for tumor if a region of low signal intensity on T2-weighted imaging within the prostate corresponded with a focally restricted area on the ADC map. A region of interest (ROI) was drawn around the suspicious lesion on a single slice of the ADC map and a corresponding ROI was drawn around presumed nontumor irradiated peripheral zone and central gland tissues on the opposite side of the prostate. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined against TRUS-guided biopsy reference standard (octant, n = 17; sextant, n = 5; two samples, n = 1; 12 samples, n = 1).

RESULTS

Sixteen of 24 patients (66.7%) had positive histology findings. The median tumor ROI area was 0.37 cm(2) (quartiles, 0.30 and 0.82 cm(2)). The sensitivity, specificity, PPV, and NPV for detecting tumor were 93.8%, 75%, 88.2%, and 85.7%, respectively. A cutoff ADC of 1216 × 10(-6) mm(2)/s could predict tumor with 100% sensitivity and 96% specificity (area under the receiver operating characteristic curve = 0.992).

CONCLUSION

An ADC derived from DWI is a useful adjunct to T2-weighted MRI for detecting local tumor recurrence larger than 0.4 cm(2) within the prostate.

Image-guided radiotherapy: has it influenced patient outcomes?

Cancer control and toxicity outcomes are the mainstay of evidence-based medicine in radiation oncology. However, radiotherapy is an intricate therapy involving numerous processes that need to be executed appropriately in order for the therapy to be delivered successfully. The use of image-guided radiation therapy (IGRT), referring to imaging occurring in the radiation therapy room with per-patient adjustments, can increase the agreement between the planned and the actual dose delivered. However, the absence of direct evidence regarding the clinical benefit of IGRT has been a criticism. Here, we dissect the role of IGRT in the radiotherapy (RT) process and emphasize its role in improving the quality of the intervention. The literature is reviewed to collect evidence that supports that higher-quality dose delivery enabled by IGRT results in higher clinical control rates, reduced toxicity, and new treatment options for patients that previously were without viable options.

MR imaging of treated prostate cancer

Many management options are available to patients with newly diagnosed prostate cancer. Magnetic resonance (MR) imaging plays an important role in initial staging of prostate cancer, but it also aids in tumor detection when there is clinical or biochemical suspicion of residual or recurrent disease after treatment. The purpose of this review is to describe the normal appearances of the prostatic region after different kinds of treatment for prostate cancer and to discuss how these appearances differ from those of recurrent and residual disease. Several MR imaging techniques used in evaluating patients with prostate cancer are described, including conventional MR imaging sequences (mainly T1- and T2-weighted sequences), MR spectroscopic imaging, diffusion-weighted imaging, and dynamic contrast agent-enhanced MR imaging. Clinical considerations, together with the different approaches for interpreting serum prostate-specific antigen values in the posttreatment setting, are also presented. All forms of treatment alter the MR imaging features of the prostatic region to a greater or lesser extent, and it is important to be able to recognize expected posttreatment appearances and distinguish them from the features of recurrent or residual cancer to aid subsequent clinical management.

Focal salvage therapy for localized prostate cancer recurrence after external beam radiotherapy: a pilot study

BACKGROUND

The objective of this study was to evaluate the safety, feasibility, side-effect profile, and proof of concept for focal salvage therapy using high-intensity focused ultrasound (HIFU).

METHODS

A registry-based analysis was conducted between 2004 and 2009 of 430 patients who underwent HIFU. Thirty-nine patients received focal salvage therapy for localized recurrence after external beam radiotherapy. Multiparametric magnetic resonance imaging studies combined with transperineal template prostate mapping biopsies or transrectal biopsies were used to localize disease. Validated questionnaires were used to assess functional outcomes. Biochemical failure was defined by using both Phoenix criteria (prostate-specific antigen [PSA] nadir plus 2 ng/mL) and Stuttgart criteria (PSA nadir plus 1.2 ng/mL).

RESULTS

The mean pre-HIFU PSA level was 4.6 ng/mL. The median follow-up was 17 months (interquartile range, 10-29 months). International Index of Erectile Function-5 scores decreased from a median ± standard deviation (SD) of 18 ± 16 to 13 ± 21 at 6 months, demonstrating worsening function. Scores on the University of California Los Angeles-Expanded Prostate Cancer Index Composite Urinary domain indicate that pad-free, leak-free continence status was 64%, and the pad-free rate was 87.2% at last follow-up. One rectourethral fistula occurred and spontaneously resolved with urinary and bowel diversion. The actuarial progression-free survival rate (including PSA nonresponders) was 69% at 1 year and 49% at 2 years according to Phoenix criteria. Excluding PSA nonresponders, these rates were 74% and 58%, respectively (Phoenix criteria).

CONCLUSIONS

The results from this study indicated that focal salvage therapy is a potential strategy for localized recurrence after radiotherapy that may reduce the harms resulting from whole-gland salvage therapies.

Androgen deprivation therapy and cardiovascular risk

PURPOSE

The potential association between androgen deprivation therapy (ADT) and cardiovascular mortality (CVM) remains controversial. This study assessed mortality outcomes in a large national registry to further elucidate the association between treatment selection and cause of mortality.

PATIENTS AND METHODS

A total of 7,248 men in the CaPSURE registry were analyzed. Treatment was categorized as local only, primary ADT monotherapy, local treatment plus ADT, and watchful waiting/active surveillance (WW/AS). Competing hazards survival analysis was performed for prostate cancer-specific mortality (PCSM), CVM, and all-cause mortality. A propensity score-adjusted and a propensity-matched analysis were undertaken to adjust for imbalances in covariates among men receiving various treatments.

RESULTS

Patients treated with ADT or WW/AS had a higher likelihood of PCSM than those treated with local therapy alone. Patients treated with primary ADT had an almost two-fold greater likelihood of CVM (HR, 1.94; 95% CI, 1.29 to 2.97) than those treated with local therapy alone; however, patients treated with WW/AS had a greater than two-fold increased risk of CVM (HR, 2.46; 95% CI, 1.53 to 3.95). A propensity-matching algorithm in a subset of 1,391 patients was unable to find a significant difference in CVM between those who did or did not receive ADT.

CONCLUSION

Patients matched on propensity to receive ADT did not show an association between ADT and CVM. This suggests that potential unmeasured variables affecting treatment selection may confound the relationship between ADT use and cardiovascular risk. However, an association may yet exist, because the propensity score could not include all known risk factors for CVM.

Robotic image-guided stereotactic radiotherapy, for isolated recurrent primary, lymph node or metastatic prostate cancer

PURPOSE

To evaluate the outcome of robotic CyberKnife (Accuray, Sunnyvale, CA)-based stereotactic radiotherapy (CBK-SRT) for isolated recurrent primary, lymph node, or metastatic prostate cancer.

METHODS AND MATERIALS

Between May 2007 and December 2009, 34 consecutive patients/38 lesions were treated (15 patients reirradiated for local recurrence [P], 4 patients reirradiated for anastomosis recurrence [A], 16 patients treated for single lymph node recurrence [LN], and 3 patients treated for single metastasis [M]). In all but 4 patients, [(11)C]choline positron emission tomography/computed tomography was performed. CBK-SRT consisted of reirradiation and first radiotherapy in 27 and 11 lesions, respectively. The median CBK-SRT dose was 30 Gy in 4.5 fractions (P, 30 Gy in 5 fractions; A, 30 Gy in 5 fractions; LN, 33 Gy in 3 fractions; and M, 36 Gy in 3 fractions). In 18 patients (21 lesions) androgen deprivation was added to CBK-SRT (median duration, 16.6 months).

RESULTS

The median follow-up was 16.9 months. Acute toxicity included urinary events (3 Grade 1, 2 Grade 2, and 2 Grade 3 events) and rectal events (1 Grade 1 event). Late toxicity included urinary events (3 Grade 1, 2 Grade 2, and 2 Grade 3 events) and rectal events (1 Grade 1 event and 1 Grade 2 event). Biochemical response was observed in 32 of 38 evaluable lesions. Prostate-specific antigen stabilization was seen for 4 lesions, and in 2 cases prostate-specific antigen progression was reported. The 30-month progression-free survival rate was 42.6%. Disease progression was observed for 14 lesions (5, 2, 5, and 2 in Groups P, A, LN, and M respectively). In only 3 cases, in-field progression was seen. At the time of analysis (May 2010), 19 patients are alive with no evidence of disease and 15 are alive with disease.

CONCLUSIONS

CyberKnife-based stereotactic radiotherapy is a feasible approach for isolated recurrent primary, lymph node, or metastatic prostate cancer, offering excellent in-field tumor control and a low toxicity profile. Further investigation is warranted to identify the patients who benefit most from this treatment modality. The optimal combination with androgen deprivation should also be defined.