Nicolas Jansen

A Dosimetric Selectivity Intercomparison of HDR Brachytherapy, IMRT and Helical Tomotherapy in Prostate Cancer Radiotherapy

Background and Purpose:Dose escalation in order to improve the biochemical control in prostate cancer requires the application of irradiation techniques with high conformality. The dosimetric selectivity of three radiation modalities is compared: high-dose-rate brachytherapy (HDR-BT), intensity-modulated radiation radiotherapy (IMRT), and helical tomotherapy (HT).Patients and Methods:Ten patients with prostate adenocarcinoma treated by a 10-Gy HDR-BT boost after external-beam radiotherapy were investigated. For each patient, HDR-BT, IMRT and HT theoretical treatment plans were realized using common contour sets. A 10-Gy dose was prescribed to the planning target volume (PTV). The PTVs and critical organs’ dose-volume histograms obtained were compared using Student’s t-test.Results:HDR-BT delivers spontaneously higher mean doses to the PTV with smaller cold spots compared to IMRT and HT. 33% of the rectal volume received a mean HDR-BT dose of 3.86 ± 0.3 Gy in comparison with a mean IMRT dose of 6.57 ± 0.68 Gy and a mean HT dose of 5.58 ± 0.71 Gy (p < 0.0001). HDR-BT also enables to better spare the bladder. The hot spots inside the urethra are greater with HDR-BT. The volume of healthy tissue receiving 10% of the prescribed dose is reduced at least by a factor of 8 with HDR-BT (p < 0.0001).Conclusion:HDR-BT offers better conformality in comparison with HT and IMRT and reduces the volume of healthy tissue receiving a low dose.Hintergrund und Ziel:Eine Dosiseskalation zur Steigerung der biochemischen Kontrollraten beim Prostatakarzinom erfordert die Anwendung von Bestrahlungstechniken, die eine hohe Dosiskonformität ermöglichen. Verglichen wird die dosimetrische Selektivität von drei Bestrahlungsmodalitäten: High-Dose-Rate-Brachytherapie (HDR-BT), intensitätsmodulierte Radiotherapie (IMRT) und helikale Tomotherapie (HT).Patienten und Methodik:Zehn Patienten mit einem Adenokarzinom der Prostata, die im Anschluss an eine perkutane Radiotherapie einen Boost von 10 Gy in Form einer HDR-BT erhielten, wurden untersucht. Für jeden dieser Patienten wurden Bestrahlungspläne für eine HDR-BT, eine IMRT und eine HT unter Anwendung gemeinsamer Konturierungsverfahren erstellt. Für das Planungszielvolumen (PTV) wurden 10 Gy verordnet. Die ermittelten jeweiligen PTV und Dosis-Volumen-Histogramme für die kritischen Organe wurden mittels Student-t-Test miteinander verglichen.Ergebnisse:Die HDR-BT führt zu höheren mittleren Dosen im PTV mit kleineren Cold Spots als die IMRT oder HT. 33% des bestrahlten Volumens des Rektums erhielten bei der HDR-BT eine mittlere Dosis von 3,86 ± 0,3 Gy im Vergleich zu 6,57 ± 0,68 Gy bei der IMRT und 5,58 ± 0,71 Gy bei der HT (p < 0,0001). Die HDR-BT ermöglicht eine bessere Schonung der Harnblase. Die Dosisspitzen (Hot Spots) an der Urethra sind jedoch bei der HDR-BT höher. Das Volumen des gesunden Gewebes, das 10% der vorgeschriebenen Dosis erhält, wird bei Anwendung der HDR-BT etwa um den Faktor 8 verringert (p < 0,0001).Schlussfolgerung:Die HDR-BT führt zu einer günstigeren Dosiskonformität im Vergleich zur HT und zur IMRT und reduziert so das mit einer niedrigen Dosis belastete Volumen gesunden Gewebes.

DOSIMETRIC COMPARISON OF HIGH-DOSE-RATE BRACHYTHERAPY AND INTENSITY-MODULATED RADIATION THERAPY AS A BOOST TO THE PROSTATE

PURPOSE We compared the dose conformity of two radiation modalities: high-dose-rate brachytherapy (HDR BT) and intensity-modulated radiation therapy (IMRT) to deliver a boost to the prostate after external beam radiotherapy (EBRT). METHODS AND MATERIALS Ten successive patients with prostate adenocarcinoma treated with a single 10-Gy HDR BT boost after EBRT were investigated. Four theoretical IMRT plans were computed: (a) 32.85 Gy IMRT and (b) 26 Gy IMRT with CTV-PTV expansions, doses corresponding to the equivalent dose in 2-Gy fractions (EQD2) of one 10-Gy fraction calculated with a prostate alpha/beta ratio of respectively 1.5 and 3 Gy; and (c) 32.85 Gy IMRT and (d) 26 Gy IMRT without CTV-PTV expansions. The dose-volume histogram values converted in EQD2 with an alpha/beta ratio of 3 Gy for the organs at risk were compared. RESULTS The HDR BT plan delivered higher mean doses to the PTV compared with IMRT plans. In all, 33% of the rectal volume received a mean dose of 5.32 +/- 0.65 Gy and 20% of bladder volume received 4.61 +/- 1.24 Gy with HDR BT. In comparison, doses delivered with IMRT were respectively 13.4 +/- 1.49 Gy and 10.81 +/- 4 Gy, even if only 26 Gy was prescribed to the PTV with no CTV-PTV expansion (p < 0.0001). The hot spots inside the urethra were greater with HDR BT but acceptable. CONCLUSIONS Use of HDR BT produced a more conformal plan for the boost to the prostate than IMRT even without CTV-PTV expansions.

Clinical efficacy and toxicity of radio-chemotherapy and magnetic resonance imaging-guided brachytherapy for locally advanced cervical cancer patients: A mono-institutional experience

ABSTRACT Background. To evaluate efficacy and toxicity of radio-chemotherapy (RCT) and MR-guided pulsed-dose-rate (PDR) adaptive brachytherapy (IGABT) for locally advanced cervical cancer (LACC). Material and methods. Between 2007 and 2014 85 patients with FIGO stage 1B1 N+ or ≥ 1B2 cervical cancer were treated with RCT+ IGABT. The treatment consisted of a pelvic± paraaortic external beam radiotherapy (EBRT) (45–50.4 Gy ± 10 Gy boost to primary tumor and/or to pathologic lymph nodes) with concurrent cisplatin followed by 25–35 Gy of PDR IGABT in 30–50 pulses. The ratio of 3D-CFRT/IMRT was 61/24 patients. Dose-volume parameters of high-risk clinical target volume (HR-CTV), intermediate-risk clinical target volume (IR-CTV) and D2cm3 organs at risk (OARs) were reported. Local control (LC), cancer-specific survival (CCS) and overall survival (OS) were analyzed actuarially and morbidity crude rates were scored using CTCAEv4.0. Results. Mean follow-up was 36 months (range 6–94). The mean D90 and D98 for HR-CTV was 84.4 ± 9 Gy and 77 ± 8.1 Gy, while for IR-CTV was 69.1 ± 4.3 Gy and 64.8 ± 4.3 Gy, respectively. The mean D2cm3 for OARs was the following: bladder: 77.3 ± 10.5 Gy, rectum: 65 ± 6.8 Gy, sigmoid: 63 ± 7.9 Gy and intestine: 64.0 ± 9.1 Gy. Three year LC, CSS and OS were: 94%, 85% and 81%. The three-year regional- and distant control rates were 95% and 74%. Node negative patients had significantly higher three-year CSS (100 vs. 72%, p = 0.016) and OS (92 vs. 72%, p = 0.001) compared to node positive ones. Three-year actuarial late Grade ≥ 3 morbidity was the following: GI: 8%, GU: 5%, Vaginal: 8%. The frequency of Grade ≥ 3 hematological toxicities including anemia/leukopenia/neutropenia/thrombocytopenia were 8.6%/34.7%/24.3%/24.3%, respectively. Conclusion. This large mono-institutional experience builds up further evidences that IGABT in conjunction with RCT should be the standard of care for patients suffering LACC.

Photons, protons or carbon ions for stage I non-small cell lung cancer – Results of the multicentric ROCOCO in silico study

PURPOSE To compare dose to organs at risk (OARs) and dose-escalation possibility for 24 stage I non-small cell lung cancer (NSCLC) patients in a ROCOCO (Radiation Oncology Collaborative Comparison) trial. METHODS For each patient, 3 photon plans [Intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT) and CyberKnife], a double scattered proton (DSP) and an intensity-modulated carbon-ion (IMIT) therapy plan were created. Dose prescription was 60 Gy (equivalent) in 8 fractions. RESULTS The mean dose and dose to 2% of the clinical target volume (CTV) were lower for protons and ions compared with IMRT (p < 0.01). Doses to the lungs, heart, and mediastinal structures were lowest with IMIT (p < 0.01), doses to the spinal cord were lowest with DSP (p < 0.01). VMAT and CyberKnife allowed for reduced doses to most OARs compared with IMRT. Dose escalation was possible for 8 patients. Generally, the mediastinum was the primary dose-limiting organ. CONCLUSION On average, the doses to the OARs were lowest using particles, with more homogenous CTV doses. Given the ability of VMAT and CyberKnife to limit doses to OARs compared with IMRT, the additional benefit of particles may only be clinically relevant in selected patients and thus should be carefully weighed for every individual patient.

Clinical outcomes of 130 patients with primary and secondary lung tumors treated with Cyberknife robotic stereotactic body radiotherapy

Abstract Background Authors report clinical outcomes of patients treated with robotic stereotactic body radiotherapy (SBRT) for primary, recurrent and metastatic lung lesions. Patients and methods 130 patients with 160 lesions were treated with Cyberknife SBRT, including T1-3 primary lung cancers (54%), recurrent tumors (22%) and pulmonary metastases (24%). The mean biologically equivalent dose (BED10Gy) was 151 Gy (72–180 Gy). Median prescribed dose for peripheral and central lesions was 3×20 Gy and 3×15 Gy, respectively. Local control (LC), overall survival (OS), and cause-specific survival (CSS) rates, early and late toxicities are reported. Statistical analysis was performed to identify factors influencing local tumor control. Results Median follow-up time was 21 months. In univariate analysis, higher dose was associated with better LC and a cut-off value was detected at BED10Gy ≤ 112.5 Gy, resulting in 1-, 2-, and 3-year actuarial LC rates of 93%, vs 73%, 80% vs 61%, and 63% vs 54%, for the high and low dose groups, respectively (p = 0.0061, HR = 0.384). In multivariate analysis, metastatic origin, histological confirmation and larger Planning Target Volume (PTV) were associated with higher risk of local failure. Actuarial OS and CSS rates at 1, 2, and 3 years were 85%, 74% and 62%, and 93%, 89% and 80%, respectively. Acute and late toxicities ≥ Gr 3 were observed in 3 (2%) and 6 patients (5%), respectively. Conclusions Our favorable LC and survival rates after robotic SBRT, with low rates of severe toxicities, are coherent with the literature data in this mixed, non-selected study population.

Stereotactic Robotic Body Radiotherapy for Patients With Unresectable Hepatic Oligorecurrence

Micro‐Abstract We present our retrospective study of 42 patients treated for hepatic oligorecurrence with stereotactic body radiotherapy using the CyberKnife system (Accuray Inc). Besides reporting on acute and late toxicities, the influence of patient and lesion characteristics on local control, liver and distant progression‐free survival, and overall survival were also investigated. Background The purpose of this study was to analyze local control (LC), liver progression‐free survival (PFS), and distant PFS (DFS), overall survival (OS), and toxicity in a cohort of patients treated with stereotactic body radiotherapy (SBRT) with fiducial tracking for oligorecurrent liver lesions; and to evaluate the potential influence of lesion size, systemic treatment, physical and biologically effective dose (BED), treatment calculation algorithms and other parameters on the obtained results. Patients and Methods Unoperable patients with sufficient liver function had [18F]‐fluorodeoxyglucose‐positron emission tomography‐computed tomography and liver magnetic resonance imaging to confirm the oligorecurrent nature of the disease and to further delineate the gross tumor volume (GTV). An intended dose of 45 Gy in 3 fractions was prescribed on the 80% isodose and adapted if risk‐related. Treatment was executed with the CyberKnife system (Accuray Inc) platform using fiducials tracking. Initial plans were recalculated using the Monte Carlo algorithm. Patient and treatment data were processed using the Kaplan–Meier method and log rank test for survival analysis. Results Between 2010 and 2015, 42 patients (55 lesions) were irradiated. The mean GTV and planning target volume (PTV) were 30.5 cc and 96.8 cc, respectively. Treatments were delivered 3 times per week in a median of 3 fractions to a PTV median dose of 54.6 Gy. The mean GTV and PTV D98% were 51.6 Gy and 51.2 Gy, respectively. Heterogeneity corrections did not influence dose parameters. After a median follow‐up of 18.9 months, the 1‐ and 2‐year LC/liver PFS/DFS/OS were 81.3%/55%/62.4%/86.9%, and 76.3%/42.3%/52%/78.3%, respectively. Performance status and histology had a significant effect on LC, whereas age (older than 65 years) marginally influenced liver PFS. Clinical target volume physical dose V45 Gy > 95%, generalized equivalent uniform dose (a = −30) > 45 Gy and a BED (&agr;/&bgr; = 10) V105 Gy > 96% showed statistically significant effect on the LC. Acute Grade 3 gastrointestinal (GI) and late Grade 2 GI and fatigue toxicity were found in 5% and 11% patients, respectively. Conclusion Favorable survival and toxicity results support the potential paradigm shift in which the use of SBRT in oligorecurrent liver disease could benefit patients with unresectable or resectable liver metastases.