Abstract A great deal of quantitative information regarding the dose–volume relationships of pelvic organs at risk has been collected and analysed over the last 10 years. The need to improve our ...knowledge in the modelling of late and acute toxicity has become increasingly important, due to the rapidly increasing use of inverse-planned intensity-modulated radiotherapy (IMRT) and the consequent need of a quantitative assessment of dose–volume or biological-based cost functions. This comprehensive review concerns most organs at risk involved in planning optimisation for prostate and other types of pelvic cancer. The rectum is the most investigated organ: the largest studies on dose–volume modelling of rectal toxicity show quite consistent results, suggesting that sufficiently reliable dose–volume/EUD-based constraints can be safely applied in most clinical situations. Quantitative data on bladder, bowel, sexual organs and pelvic bone marrow are more lacking but are rapidly emerging; however, for these organs, further investigation on large groups of patients is necessary.
Abstract Background The Prostate Cancer Research International Active Surveillance (PRIAS) study was initiated a decade ago to study the most optimal selection and follow-up of men on active ...surveillance (AS). Objective We report on 10 yr of follow-up of men on AS in the PRIAS study and evaluate if criteria used to recommend a switch to active treatment truly predict unfavorable outcome on subsequent radical prostatectomy (RP). Design, setting, and participants Men with low-risk prostate cancer were included and followed prospectively on AS. Follow-up consisted of regular prostate-specific antigen (PSA) tests, digital rectal examinations, and biopsies. Men with Gleason >3 + 3, more than two positive biopsy cores, or stage higher than cT2 were advised to switch to active treatment (until 2014, a PSA doubling time PSA DT of 0–3 yr was also used). Outcome measurements and statistical analysis Reclassification rates, treatment after discontinuation, and outcome on RP after discontinuing AS were reported. Regression analysis on the outcome of RP was used to evaluate the predictive value of criteria currently used to recommend a switch to active treatment. Kaplan-Meier and competing risk analysis were used to report discontinuation rates over time and long-term oncologic end points. Results and limitations A total of 5302 men were included in PRIAS across 18 countries. Reclassification rates remained stable on all subsequent biopsies, with 22–33% of men having either Gleason >3 + 3 or more than two positive cores on any repeat biopsy. At 5 and 10 yr of follow-up, 52% and 73% of men, respectively, had discontinued AS, most of them because of protocol-based reclassification. A third of men undergoing subsequent RP had favorable pathologic tumor features (Gleason 3 + 3 and pT2). Of the criteria used to recommend a switch to active treatment, more than two positive cores and a PSA DT of 0–3 yr were not predictive of unfavorable pathologic outcome on RP. Conclusions A substantial group of men discontinued AS without subsequent unfavorable tumor features on RP; therefore, we propose Gleason upgrading and cT3 as the only indicators for an immediate switch to active treatment. Surrogate indicators (eg, more than two positive cores and a fast-rising PSA) should not trigger immediate active treatment but rather further investigation to confirm the suspicion of higher risk disease. Patient summary We confirmed the safety of active surveillance as a treatment option for men with low-risk prostate cancer; however, some changes could be made to the follow-up protocol to safely increase the number of men who remain on active surveillance.
Purpose
Despite its increasing application, radiomics has not yet demonstrated a solid reliability, due to the difficulty in replicating analyses. The extraction of radiomic features from clinical ...MRI (T1w/T2w) presents even more challenges because of the absence of well‐defined units (e.g. HU). Some preprocessing steps are required before the estimation of radiomic features and one of this is the intensity normalization, that can be performed using different methods. The aim of this work was to evaluate the effect of three different normalization techniques, applied on T2w‐MRI images of the pelvic region, on radiomic features reproducibility.
Methods
T2w‐MRI acquired before (MRI1) and 12 months after radiotherapy (MRI2) from 14 patients treated for prostate cancer were considered. Four different conditions were analyzed: (a) the original MRI (No_Norm); (b) MRI normalized by the mean image value (Norm_Mean); (c) MRI normalized by the mean value of the urine in the bladder (Norm_ROI); (d) MRI normalized by the histogram‐matching method (Norm_HM). Ninety‐one radiomic features were extracted from three organs of interest (prostate, internal obturator muscles and bulb) at both time‐points and on each image discretized using a fixed bin‐width approach and the difference between the two time‐points was calculated (Δfeature). To estimate the effect of normalization methods on the reproducibility of radiomic features, ICC was calculated in three analyses: (a) considering the features extracted on MRI2 in the four conditions together and considering the influence of each method separately, with respect to No_Norm; (b) considering the features extracted on MRI2 in the four conditions with respect to the inter‐observer variability in region of interest (ROI) contouring, considering also the effect of the discretization approach; (c) considering Δfeature to evaluate if some indices can recover some consistency when differences are calculated.
Results
Nearly 60% of the features have shown poor reproducibility (ICC < 0.5) on MRI2 and the method that most affected features reliability was Norm_ROI (average ICC of 0.45). The other two methods were similar, except for first‐order features, where Norm_HM outperformed Norm_Mean (average ICC = 0.33 and 0.76 for Norm_Mean and Norm_HM, respectively). In the inter‐observer setting, the number of reproducible features varied in the three structures, being higher in the prostate than in the penile bulb and in the obturators. The analysis on Δfeature highlighted that more than 60% of the features were not consistent with respect to the normalization method and confirmed the high reproducibility of the features between Norm_Mean and Norm_HM, whereas Norm_ROI was the less reproducible method.
Conclusions
The normalization process impacts the reproducibility of radiomic features, both in terms of changes in the image information content and in the inter‐observer setting. Among the considered methods, Norm_Mean and Norm_HM seem to provide the most reproducible features with respect to the original image and also between themselves, whereas Norm_ROI generates less reproducible features. Only a very small subset of feature remained reproducible and independent in any tested condition, regardless the ROI and the adopted algorithm: skewness or kurtosis, correlation and one among Imc2, Idmn and Idn from GLCM group.
Though miR-205 function has been largely characterized, the nature of its host gene, MIR205HG, is still completely unknown. Here, we show that only lowly expressed alternatively spliced MIR205HG ...transcripts act as de facto pri-miRNAs, through a process that involves Drosha to prevent unfavorable splicing and directly mediate miR-205 excision. Notably, MIR205HG-specific processed transcripts revealed to be functional per se as nuclear long noncoding RNA capable of regulating differentiation of human prostate basal cells through control of the interferon pathway. At molecular level, MIR205HG directly binds the promoters of its target genes, which have an Alu element in proximity of the Interferon-Regulatory Factor (IRF) binding site, and represses their transcription likely buffering IRF1 activity, with the ultimate effect of preventing luminal differentiation. As MIR205HG functions autonomously from (albeit complementing) miR-205 in preserving the basal identity of prostate epithelial cells, it warrants reannotation as LEADeR (Long Epithelial Alu-interacting Differentiation-related RNA).
Abstract Radiotherapy is one of the main treatment choices for non-metastatic prostate cancer (PCa), although development of radioresistance limits its effectiveness. Mounting evidence supports the ...ability of microRNAs to interfere with different radioresistance-associated pathways, suggesting their potential as radiosensitizers. Here, we demonstrate that reconstitution of miR-875-5p , whose expression is down-regulated in PCa clinical samples and directly correlates with that of E-cadherin, was able to enhance radiation response in PCa cell lines and xenografts through EGFR direct targeting. Consistent with the established role of EGFR in sustaining epithelial-to-mesenchymal transition (EMT) and promoting DNA repair following radiation-induced nuclear translocation, we found that miR-875-5p reconstitution in PCa cells counteracted EMT and impaired DNA lesion clearance. Down-regulation of the EMT-inducing transcription factor ZEB1, which also plays a role in homologous recombination-mediated repair of DNA lesions by regulating CHK1 expression, was found to be a major determinant of miR-875-5p -induced radiosensitization, as confirmed by phenocopy experiments showing that siRNA-mediated ZEB1 knock-down was able to reproduce the microRNA radiosensitizing effect. Overall, our data support the clinical interest in developing a novel therapeutic approach based on miR-875-5p reconstitution to increase PCa response to radiotherapy.
Abstract Background Overdiagnosis and subsequent overtreatment are important side effects of screening for, and early detection of, prostate cancer (PCa). Active surveillance (AS) is of growing ...interest as an alternative to radical treatment of low-risk PCa. Objective To update our experience in the largest worldwide prospective AS cohort. Design, setting, and participants Eligible patients had clinical stage T1/T2 PCa, prostate-specific antigen (PSA) ≤10 ng/ml, PSA density <0.2 ng/ml per milliliter, one or two positive biopsy cores, and Gleason score ≤6. PSA was measured every 3–6 mo, and volume-based repeat biopsies were scheduled after 1, 4, and 7 yr. Reclassification was defined as more than two positive cores or Gleason >6 at repeat biopsy. Recommendation for treatment was triggered in case of PSA doubling time <3 yr or reclassification. Outcome measurements and statistical analysis Multivariate regression analysis was used to evaluate predictors for reclassification at repeat biopsy. Active therapy–free survival (ATFS) was assessed with a Kaplan-Meier analysis, and Cox regression was used to evaluate the association of clinical characteristics with active therapy over time. Results and limitations In total, 2494 patients were included and followed for a median of 1.6 yr. One or more repeat biopsies were performed in 1480 men, of whom 415 men (28%) showed reclassification. Compliance with the first repeat biopsy was estimated to be 81%. During follow-up, 527 patients (21.1%) underwent active therapy. ATFS at 2 yr was 77.3%. The strongest predictors for reclassification and switching to deferred treatment were the number of positive cores (two cores compared with one core) and PSA density. The disease-specific survival rate was 100%. Follow-up was too short to draw definitive conclusions about the safety of AS. Conclusions Our short-term data support AS as a feasible strategy to reduce overtreatment. Clinical characteristics and PSA kinetics during follow-up can be used for risk stratification. Strict monitoring is even more essential in men with high-risk features to enable timely recognition of potentially aggressive disease and offer curative intervention. Limitations of using surrogate end points and markers in AS should be recognized. Trial registration The current program is registered at the Dutch Trial Register with ID NTR1718 ( http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1718 ).
Compelling evidence suggests that epithelial-to-mesenchymal transition is involved in the resistance of human cancer cells to chemotherapy. We previously reported that the expression of miR-205, a ...miRNA down-regulated in prostate cancer, is further repressed in prostate cancer cells undergoing epithelial-to-mesenchymal transition, suggesting a possible involvement of the miRNA in the acquisition of the chemoresistant phenotype. In the present study, we show that miR-205 replacement in castration-resistant mesenchymal prostate cancer cells caused an enhancement of cisplatin cytotoxic activity in vitro and in vivo, as a consequence of autophagy impairment. Specifically, the constraints on the autophagic flux were associated to the miRNA-dependent down-regulation of the lysosome-associated proteins RAB27A and LAMP3. These findings suggest that miR-205-mediated impairment of the autophagic pathway may interfere with the detoxifying capabilities of prostate cancer cells in their attempt to cope with cisplatin-induced detrimental effects. Overall, our data indicate that (i) loss of miR-205 may indeed contribute to acquire mesenchymal tracts and concomitantly establish a permissive autophagic milieu that confers a chemotherapy resistant phenotype to prostate cancer cells, and (ii) strategies aimed at restoring miR-205 expression levels may represent a successful approach to overcome resistance of prostate cancer to platinum compounds.
Aberrant expression of microRNAs, small non-coding RNA molecules that post-transcriptionally repress gene expression, seems to be causatively linked to the pathogenesis of cancer. In this context, ...miR-21 was found to be overexpressed in different human cancers (e.g. glioblastoma, breast cancer). In addition, it is thought to be endowed with oncogenic properties due to its ability to negatively modulate the expression of tumor-suppressor genes (e.g. PTEN) and to cause the reversion of malignant phenotype when knocked- down in several tumor models. On the basis of these findings, miR-21 has been proposed as a widely exploitable cancer-related target. However, scanty information is available concerning the relevance of miR-21 for prostate cancer. In the present study, we investigated the role of miR-21 and its potential as a therapeutic target in two prostate cancer cell lines, characterized by different miR-21 expression levels and PTEN gene status.
We provide evidence that miR-21 knockdown in prostate cancer cells is not sufficient per se i) to affect the proliferative and invasive potential or the chemo- and radiosensitivity profiles or ii) to modulate the expression of the tumor-suppressors PTEN and Pdcd4, which in other tumor types were found to be regulated by miR-21. We also show that miR-21 is not differently expressed in carcinomas and matched normal tissues obtained from 36 untreated prostate cancer patients subjected to radical prostatectomy.
Overall, our data suggest that miR-21 is not a central player in the onset of prostate cancer and that its single hitting is not a valuable therapeutic strategy in the disease. This supports the notion that the oncogenic properties of miR-21 could be cell and tissue dependent and that the potential role of a given miRNA as a therapeutic target should be contextualized with respect to the disease.
Radiotherapy is one of the main treatment options for non-metastatic prostate cancer (PCa). Although treatment technical optimization has greatly improved local tumor control, a considerable fraction ...of patients still experience relapse due to the development of resistance. Radioresistance is a complex and still poorly understood phenomenon involving the deregulation of a variety of signaling pathways as a consequence of several genetic and epigenetic abnormalities. In this context, cumulative evidence supports a functional role of microRNAs in affecting radioresistance, suggesting the modulation of their expression as a novel radiosensitizing approach. Here, we investigated for the first time the ability of miR-205 to enhance the radiation response of PCa models.
miR-205 reconstitution by a miRNA mimic in PCa cell lines (DU145 and PC-3) was used to elucidate miR-205 biological role. Radiation response in miRNA-reconstituted and control cells was assessed by clonogenic assay, immunofluorescence-based detection of nuclear γ-H2AX foci and comet assay. RNAi was used to silence the miRNA targets PKCε or ZEB1. In addition, target-protection experiments were carried out using a custom oligonucleotide designed to physically disrupt the pairing between the miR-205 and PKCε. For in vivo experiments, xenografts generated in SCID mice by implanting DU145 cells stably expressing miR-205 were exposed to 5-Gy single dose irradiation using an image-guided animal micro-irradiator.
miR-205 reconstitution was able to significantly enhance the radiation response of prostate cancer cell lines and xenografts through the impairment of radiation-induced DNA damage repair, as a consequence of PKCε and ZEB1 inhibition. Indeed, phenocopy experiments based on knock-down of either PKCε or ZEB1 reproduced miR-205 radiosensitizing effect, hence confirming a functional role of both targets in the process. At the molecular level, miR-205-induced suppression of PKCε counteracted radioresistance through the impairment of EGFR nuclear translocation and the consequent DNA-PK activation. Consistently, disruption of miR-205-PKCε 3'UTR pairing almost completely abrogated the radiosensitizing effect.
Our results uncovered the molecular and cellular mechanisms underlying the radiosensitizing effect of miR-205. These findings support the clinical interest in developing a novel therapeutic approach based on miR-205 reconstitution to increase PCa response to radiotherapy.
Purpose
REASSURE is a global, prospective, non-interventional study to assess long-term safety of radium-223 in patients with bone metastatic castration-resistant prostate cancer. Here we report an ...interim analysis of patients according to previous use of chemotherapy.
Methods
Radium-223 was administered in routine clinical practice. Interim safety analysis was planned after enrolment of the first 600 patients. Patient characteristics and safety data by previous administration of chemotherapy (docetaxel and/or cabazitaxel) were investigated.
Results
This interim analysis included 583 patients. Median duration of observation was 7 months (range, 0–20). Nineteen patients treated with concomitant chemotherapy were excluded, 564 (97%) were eligible for exploratory analysis according to prior use of chemotherapy; 190 (34%) had previously received and completed chemotherapy, and 374 (66%) had not. In the prior versus no prior chemotherapy group, a higher proportion of patients had an Eastern Cooperative Oncology Group performance status of ≥2 (22% vs 11%) and > 20 metastatic lesions (26% vs 15%), median alkaline phosphatase (162.0 vs 115.0 U/L) and prostate-specific antigen (132.0 vs 40.2 ng/mL) levels were higher, and a lower proportion completed 6 radium-223 injections (45% vs 63%). Drug-related treatment-emergent adverse events (TEAEs) occurred in 63 and 48%, and haematological drug-related TEAEs in 21 and 9% of patients who had or had not previously received chemotherapy. Four drug-related deaths were reported, all in the prior chemotherapy group.
Conclusions
The short-term safety profile of radium-223 in routine clinical practice was comparable to other clinical studies, irrespective of prior chemotherapy use. Haematological TEAEs occurred more frequently in the prior chemotherapy group, presumably due to decreased bone marrow function as a consequence of more advanced disease and prior exposure to cytotoxic therapy. Patients who had not previously received chemotherapy appeared to have a lower burden of disease at baseline, and a lower proportion discontinued radium-223 treatment.
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