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Featured researches published by Piet Ost.


European Urology | 2015

Metastasis-directed Therapy of Regional and Distant Recurrences After Curative Treatment of Prostate Cancer: A Systematic Review of the Literature

Piet Ost; Alberto Bossi; Karel Decaestecker; Gert De Meerleer; Gianluca Giannarini; R. Jeffrey Karnes; Mack Roach; Alberto Briganti

CONTEXT The introduction of novel imaging modalities has increased the detection of oligometastatic prostate cancer (PCa) recurrence, potentially justifying the use of a metastasis-directed therapy (MDT) with surgery or radiotherapy (RT) rather than a systemic approach. OBJECTIVE To perform a systematic review of MDT for oligometastatic PCa recurrence. EVIDENCE ACQUISITION This systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. We searched the Medline and Embase databases from 1946 to February 2014 for studies reporting on biochemical or clinical progression and/or toxicity or complications of MDT (RT or surgery). Reports were excluded if these end points could not be ascertained or separately analysed, or if insufficient details were provided. Methodological quality was assessed using an 18-item validated quality appraisal tool for case series. EVIDENCE SYNTHESIS Fifteen single-arm case series reporting on a total of 450 patients met the inclusion criteria. Seven studies were considered of acceptable quality. Oligometastatic PCa recurrence was diagnosed with positron emission tomography with coregistered computed tomography in most of the patients (98%). Nodal, bone, and visceral metastases were treated in 78%, 21%, and 1%, respectively. Patients were treated with either RT (66%) or lymph node dissection (LND) (34%). Adjuvant androgen deprivation was given in 61% of patients (n=275). In the case of nodal metastases, prophylactic nodal irradiation was administered in 49% of patients (n=172). Overall, 51% of patients were progression free 1-3 yr after salvage MDT, with most of them receiving adjuvant treatment. For RT, grade 2 toxicity was observed in 8.5% of patients, with one case of grade 3 toxicity. In the case of LND, 11% and 12% of grade 2 and grade 3 complications, respectively, were reported. CONCLUSIONS MDT is a promising approach for oligometastatic PCa recurrence, but the low level of evidence generated by small case series does not allow extrapolation to a standard of care. PATIENT SUMMARY We performed a systematic review to assess complications and outcomes of treating oligometastatic prostate cancer recurrence with surgery or radiotherapy. We concluded that although this approach is promising, it requires validation in randomised controlled trials.


Clinical Genitourinary Cancer | 2013

Salvage Stereotactic Body Radiotherapy for Patients With Limited Prostate Cancer Metastases: Deferring Androgen Deprivation Therapy

P. Berkovic; Gert De Meerleer; Louke Delrue; Bieke Lambert; Valérie Fonteyne; Nicolaas Lumen; Karel Decaestecker; Geert Villeirs; Philippe Vuye; Piet Ost

BACKGROUND We investigated whether repeated stereotactic body radiotherapy (SBRT) of oligometastatic disease is able to defer the initiation of palliative androgen deprivation therapy (ADT) in patients with low-volume bone and lymph node metastases. PATIENTS AND METHODS Patients with up to 3 synchronous metastases (bone and/or lymph nodes) diagnosed on positron emission tomography, following biochemical recurrence after local curative treatment, were treated with (repeated) SBRT to a dose of 50 Gy in 10 fractions. Androgen deprivation therapy-free survival (ADT-FS) defined as the time interval between the first day of SBRT and the initiation of ADT was the primary end point. ADT was initiated if more than 3 metastases were detected during follow-up even when patients were still asymptomatic or in case of a prostate specific antigen elevation above 50 ng/mL in the absence of metastases. Secondary end points were local control, clinical progression-free survival, and toxicity. Toxicity was scored using the Common Terminology Criteria for Adverse Events. RESULTS We treated 24 patients with a median follow-up of 24 months. Ten patients started with ADT resulting in a median ADT-FS of 38 months. The 2-year local control and clinical progression-free survival was 100% and 42%, respectively. Eleven and 3 patients, respectively, required a second and third salvage treatment for metachronous low-volume metastatic disease. No grade 3 toxicity was observed. CONCLUSION Repeated salvage SBRT is feasible, well tolerated and defers palliative ADT with a median of 38 months in patients with limited bone or lymph node PCa metastases.


European Urology | 2016

Progression-free Survival Following Stereotactic Body Radiotherapy for Oligometastatic Prostate Cancer Treatment-naive Recurrence: A Multi-institutional Analysis

Piet Ost; Barbara Alicja Jereczek-Fossa; Nicholas Van As; Thomas Zilli; Alexander Muacevic; Kenneth R. Olivier; D. Henderson; Franco Casamassima; Roberto Orecchia; Alessia Surgo; Lindsay C. Brown; A. Tree; Raymond Miralbell; Gert De Meerleer

UNLABELLED The literature on metastasis-directed therapy for oligometastatic prostate cancer (PCa) recurrence consists of small heterogeneous studies. This study aimed to reduce the heterogeneity by pooling individual patient data from different institutions treating oligometastatic PCa recurrence with stereotactic body radiotherapy (SBRT). We focussed on patients who were treatment naive, with the aim of determining if SBRT could delay disease progression. We included patients with three or fewer metastases. The Kaplan-Meier method was used to estimate distant progression-free survival (DPFS) and local progression-free survival (LPFS). Toxicity was scored using the Common Terminology Criteria for Adverse Events. In total, 163 metastases were treated in 119 patients. The median DPFS was 21 mo (95% confidence interval, 15-26 mo). A lower radiotherapy dose predicted a higher local recurrence rate with a 3-yr LPFS of 79% for patients treated with a biologically effective dose ≤100Gy versus 99% for patients treated with >100Gy (p=0.01). Seventeen patients (14%) developed toxicity classified as grade 1, and three patients (3%) developed grade 2 toxicity. No grade ≥3 toxicity occurred. These results should serve as a benchmark for future prospective trials. PATIENT SUMMARY This multi-institutional study pools all of the available data on the use of stereotactic body radiotherapy for limited prostate cancer metastases. We concluded that this approach is safe and associated with a prolonged treatment progression-free survival.


Cancer | 2005

Postoperative intensity-modulated radiotherapy in sinonasal carcinoma - Clinical results in 39 patients

Wim Duthoy; Tom Boterberg; Filip Claus; Piet Ost; Luc Vakaet; Samuel Bral; Frederic Duprez; Marianne Van Landuyt; Hubert Vermeersch; Wilfried De Neve

Carcinoma of the paranasal sinuses is rare. Standard therapeutic modalities consist of surgery and radiotherapy (RT). Because of the often advanced stage and the vicinity of optic structures, RT‐induced ocular toxicity is a feared side effect of conventional RT. Intensity‐modulated radiotherapy (IMRT) is a relatively new technique, which is implemented with the hypothesis that, compared with conventional RT, it would result in a lower rate of ocular toxicity for an equal local control (LC).


International Journal of Radiation Oncology Biology Physics | 2011

Volumetric Arc Therapy and Intensity-Modulated Radiotherapy for Primary Prostate Radiotherapy With Simultaneous Integrated Boost to Intraprostatic Lesion With 6 and 18 MV: A Planning Comparison Study

Piet Ost; Bruno Speleers; Gert De Meerleer; Wilfried De Neve; Valérie Fonteyne; Geert Villeirs; Werner De Gersem

PURPOSE The aim of the present study was to compare intensity-modulated radiotherapy (IMRT) with volumetric arc therapy (VMAT), in the treatment of prostate cancer with maximal dose escalation to the intraprostatic lesion (IPL), without violating the organ-at-risk constraints. Additionally, the use of 6-MV photons was compared with 18-MV photons for all techniques. METHODS AND MATERIALS A total of 12 consecutive prostate cancer patients with an IPL on magnetic resonance imaging were selected for the present study. Plans were made for three IMRT field setups (three, five, and seven fields) and one VMAT field setup (single arc). First, optimal plans were created for every technique using biologic and physical planning aims. Next, an additional escalation to the IPL was planned as high as possible without violating the planning aims of the first step. RESULTS No interaction between the technique and photon energy (p=.928) occurred. No differences were found between the 6- and 18-MV photon beams, except for a reduction in the number of monitor units needed for 18 MV (p<.05). All techniques, except for three-field IMRT, allowed for dose escalation to a median dose of ≥93±6 Gy (mean±standard deviation) to the IPL. VMAT was superior to IMRT for rectal volumes receiving 20-50 Gy (p<.05). CONCLUSION VMAT allowed for dose escalation to the IPL with better sparing of the rectum than static three-, five-, and seven-field IMRT setups. High-energy photons had no advantage over low-energy photons.


Radiotherapy and Oncology | 2008

Salvage intensity-modulated radiotherapy for rising PSA after radical prostatectomy

Gert De Meerleer; Valérie Fonteyne; Sabine Meersschout; Caroline Van den Broecke; Geert Villeirs; Nicolaas Lumen; Piet Ost; Katrien Vandecasteele; Wilfried De Neve

INTRODUCTION The aim was to prospectively evaluate both acute and late toxicity and biochemical non-evidence of disease (bNED) in patients treated with salvage intensity-modulated radiotherapy (IMRT) +/- androgen deprivation (AD) for biochemical relapse after radical prostatectomy (RP). MATERIALS AND METHODS IMRT was prescribed to a mean prescription dose to the planning target volume (PTV) of 75 Gy to be delivered in 37 fractions of 2 Gy. In total, 135 patients were treated with IMRT. Median age was 64 years. Median PSA level was 0.8 ng/ml. AD was initiated in 94 patients. Indications were perineural invasion, seminal vesicle invasion or Gleason score > or = 8 at RP. (1) Acute toxicity (n = 135). All patients were available for this analysis. Acute toxicity was scored using an in-house developed scoring system. (2) Late toxicity (n = 68). Only patients with a follow-up of at least 18 months were considered for late toxicity analysis. The RILIT score was used to register gastro-intestinal (GI) toxicity. An in-house developed scale was used to register genito-urinary (GU) toxicity. (3) bNED (n = 87). For bNED, all AD-naive patients (n = 38) together with the AD-positive patients with a follow-up > or = 18 months (n = 49) were considered. Factors influencing the results of salvage treatment were analyzed. RESULTS (1) Acute toxicity (n = 135). No patient developed grade 3 GI toxicity. We observed grade 2 toxicity in 20 patients. Four patients developed grade 3 GU toxicity. (2) Late toxicity (n = 68). One patient developed grade 3 rectal blood loss. One patient developed grade 3 anal pain (anal fissure). We observed grade 2 GI toxicity in 9 patients. Two patients developed grade 3GU toxicity. Twenty-one patients developed grade 2 GU toxicity. We observed an urethral stricture in 5 patients. (3) bNED (n = 87). The 3- and 5-year bNED was 67%. Gleason score at RP, perineural invasion and capsular perforation were significant predictors for bNED. PSA before IMRT (<1.0 vs. 1.0 ng/ml) showed a trend in predicting bNED (p = 0.08). CONCLUSION IMRT to 75Gy+/-AD can be delivered with low levels of acute and late toxicity. In patients without perineural invasion and capsular invasion and with a Gleason score > or = 7 (3 + 4), IMRT offers very good 5-years bNED.


The Prostate | 2014

Prognostic factors influencing prostate cancer-specific survival in non-castrate patients with metastatic prostate cancer.

Piet Ost; Karel Decaestecker; Bieke Lambert; Valérie Fonteyne; Louke Delrue; Nicolaas Lumen; Filip Ameye; Gert De Meerleer

In non‐castrate prostate cancer (PCa), the prognostic value of the number of metastases on prostate cancer‐specific survival (PCSS) is not well studied.


International Journal of Radiation Oncology Biology Physics | 2011

A Matched Control Analysis of Adjuvant and Salvage High-Dose Postoperative Intensity-Modulated Radiotherapy for Prostate Cancer

Piet Ost; Bart De Troyer; Valérie Fonteyne; Willem Oosterlinck; Gert De Meerleer

PURPOSE It is unclear whether immediate adjuvant radiotherapy for high-risk disease at prostatectomy (capsule perforation, seminal vesicle invasion, and/or positive surgical margins) is equivalent to delayed salvage radiotherapy at biochemical recurrence. We performed a matched case analysis comparing high-dose adjuvant intensity modulated radiotherapy (A-IMRT) with salvage IMRT (S-IMRT). METHODS AND MATERIALS One hundred forty-four patients with high-risk disease at prostatectomy were referred for A-IMRT, and 134 patients with high-risk disease were referred at biochemical recurrence (rising prostate-specific antigen [PSA], following prostatectomy, above 0.2 ng/ml) for S-IMRT. Patients were matched in a 1:1 ratio according to preoperative PSA level, Gleason score, and pT stage. Median doses of 74 Gy and 76 Gy were prescribed for A-IMRT and S-IMRT, respectively. We report biochemical relapse free survival (bRFS) rates using the Kaplan-Meier method. Univariate and multivariate analyses were used to examine tumour- and treatment-related factors. RESULTS A total of 178 patients were matched (89:89). From the end of radiotherapy, the median follow-up was 36 months for both groups. The 3-year bRFS rate for the A-IMRT group was 90% compared to 65% for the S-IMRT group (p < 0.05). On multivariate analysis, S-IMRT, Gleason grades of ≥ 4+3, perineural invasion, preoperative PSA level of ≥ 10 ng/ml, and omission of androgen deprivation (AD) were independent predictors for a reduced bRFS (p < 0.05). From the date of surgery, the median follow-up was 43 and 60 months for A-IMRT and S-IMRT, respectively. The 3-year bRFS rate for A-IMRT was 91% compared to 79% for S-IMRT (p < 0.05). On multivariate analysis, Gleason grades of ≥ 4+3, perineural invasion, and omission of AD were independent predictors for a reduced bRFS (p < 0.05). S-IMRT was no longer an independent prognostic factor (p = 0.08). CONCLUSIONS High-dose A-IMRT significantly improves 3-year bRFS compared to S-IMRT. Gleason grades of ≥ 4+3, perineural invasion, and omission of AD were independent prognostic factors for a decreased bRFS, both from the dates of surgery and from radiotherapy.


European Urology | 2009

Adjuvant High-Dose Intensity-Modulated Radiotherapy after Radical Prostatectomy for Prostate Cancer: Clinical Results in 104 Patients

Piet Ost; Valérie Fonteyne; Geert Villeirs; Nicolaas Lumen; Willem Oosterlinck; Gert De Meerleer

BACKGROUND Approximately 25% of patients treated with adjuvant radiotherapy (RT) will develop a biochemical failure within 5 yr after RT when doses of 60-64 Gray (Gy) are used. OBJECTIVE To report on the safety and biochemical outcome of adjuvant intensity-modulated RT (IMRT) with doses >70 Gy. DESIGN, SETTING, AND PARTICIPANTS Between 1999 and 2008, 104 patients underwent radical prostatectomy (RP) followed by adjuvant IMRT with or without androgen deprivation (AD) with a median follow-up of 36 mo. Indications for adjuvant IMRT were capsule perforation, seminal vesicle invasion (SVI) and/or positive surgical margins at prostatectomy specimen. All patients were irradiated at a single tertiary academic centre. AD was initiated on the basis of SVI, a preprostatectomy prostate-specific antigen level >20 ng/ml, Gleason score > or = 4+3 (n=36), or personal preference of the referring urologist (n=32). INTERVENTION A median dose of 74 Gy was prescribed to the planning target volume using IMRT in all patients. AD consisted out of a luteinising hormone-releasing hormone analogue for 6 mo. MEASUREMENTS We report on acute and late toxicity, biochemical relapse-free survival (bRFS), and clinical progression. The Kaplan-Meier method was used to estimate bRFS. Univariate analysis was used to examine the influence of patient- and treatment-related factors on bRFS. RESULTS AND LIMITATIONS With respect to acute toxicity, no patients developed grade 3 gastrointestinal (GI) toxicity, and eight patients developed grade 3 genitourinary (GU) toxicity (8%). With respect to late toxicity, no patients developed grade 3 GI toxicity, and four patients (4%) developed grade 3 GU toxicity. A urethral stricture was observed in six patients (6%). The 3- and 5-yr actuarial bRFS was 93%. On univariate analysis, bRFS rates were worse when SVI (p<0.02), Gleason score > or = 4+3 (p<0.02), or negative surgical margins (p<0.02) were present. AD did not influence bRFS. Six patients had a clinical relapse. CONCLUSIONS Adjuvant high-dose IMRT after prostatectomy is safe and bRFS is excellent.


European Urology | 2011

High-Dose Salvage Intensity-Modulated Radiotherapy With or Without Androgen Deprivation After Radical Prostatectomy for Rising or Persisting Prostate-Specific Antigen: 5-Year Results

Piet Ost; Nicolaas Lumen; An-Sofie Goessaert; Valérie Fonteyne; Bart De Troyer; Filip Jacobs; Gert De Meerleer

BACKGROUND Long-term results with salvage radiotherapy (SRT) for a biochemical recurrence after radical prostatectomy (RP) are poor. It has been suggested that radiotherapy doses >70 Gy might result in improved outcome. OBJECTIVE To report on the late toxicity profile and outcome of patients treated with high-dose salvage intensity-modulated radiotherapy (HD-SIMRT) with or without androgen deprivation (AD). DESIGN, SETTING, AND PARTICIPANTS Between 1999 and 2008, 136 patients were referred for HD-SIMRT with or without AD. The median follow-up was 5 yr. Indications for HD-SIMRT were persisting prostate-specific antigen (PSA) or a rising PSA following RP. All patients were irradiated at a single, tertiary, academic centre. AD was initiated on the basis of seminal vesicle invasion, preprostatectomy PSA >20 ng/ml, Gleason score ≥ 4+3 (n=43), or personal preference of the referring urologist (n=54). INTERVENTION A median 76-Gy dose was prescribed to the RP bed using intensity-modulated radiotherapy (IMRT) in all patients. AD consisted of a luteinising hormone-releasing hormone analogue for 6 mo. MEASUREMENTS Univariate and multivariate analyses were used to examine the influence of patient- and treatment-related factors on late toxicity, biochemical relapse-free survival (bRFS), and clinical relapse-free survival (cRFS). RESULTS AND LIMITATIONS The 5-yr actuarial bRFS and cRFS were 56% and 86%, respectively. On multivariate analysis, the presence of perineural invasion at RP (hazard ratio [HR]: 6.19, p=0.001) and an increasing pre-SRT PSA (PSA 0.5 ng/ml: HR: 1; PSA 1-1.5 ng/ml: HR: 1.60, p=0.30; and PSA >1 ng/ml: HR: 2.70, p=0.02) were independent factors for a decreased bRFS. The addition of AD improved bRFS (HR: 0.33, p=0.005). On multivariate analysis, none of the variables was a predictor of cRFS. The 5-yr risk of grade 2-3 toxicity was 22% and 8% for genitourinary and gastrointestinal symptoms, respectively. CONCLUSIONS IMRT allows for safe dose escalation to 76Gy with good bRFS.

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Gert De Meerleer

Katholieke Universiteit Leuven

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Nicolaas Lumen

Ghent University Hospital

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Geert Villeirs

Ghent University Hospital

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G. De Meerleer

Ghent University Hospital

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Alberto Briganti

Vita-Salute San Raffaele University

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Giorgio Gandaglia

Vita-Salute San Raffaele University

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