Image-guided Volumetric Modulated Arc Therapy Research Articles

Global assessment of swallow function (GASF) following VMAT radiotherapy for head and neck squamous cell carcinoma

AimThis study aimed to conduct a global assessment of swallow function (GASF) using a range of swallow outcome tools, in a cohort of patients pre- and post-treatment with image-guided volumetric modulated arc therapy (VMAT) radiotherapy. Materials and methodsAll patients receiving radical (chemo)radiation for SCC of the larynx, oro-, hypo- or nasopharynx between October 2016 – 2021 were eligible for inclusion.Patients were treated with VMAT radiotherapy according to institutional and national protocols.Patients underwent GASF pre- and 6 months post-treatment. Data were collated from the MD Anderson Dysphagia Inventory (MDADI), the Functional Oral Intake Scale (FOIS), the Performance Status Scale-Head and Neck: Normalcy of Diet scale (PSS-NoD), the 100 ml water swallow test (WST) for capacity and maximal interincisal opening (MIO). ResultsOne hundred and seventy-five patients were included. 55.2 % of patients experienced a fall in MDADI-Composite score greater than the published meaningful clinical important difference (MCID).A trend for a decrease in FOIS score reflects a decrease in range of diet textures and increase in reliance on enteral feeding at 6 months post-treatment.Mean PSS-NoD score decreased reflecting increased restriction in diet textures.20 patients’ WST capacity improved by the minimal clinically important difference of > 4mls whilst 37 % of patients experienced a decrease in WST capacity of 4mls or more. 12.6 % of patients developed trismus following radiotherapy. ConclusionsThis paper adds new detail to the understanding of the decline in measured eating, drinking and swallowing function that patients treated with VMAT radiotherapyexperience at 6 months post treatment. However, gaps are highlighted in the evidence base in terms of interpretation of swallow outcomes tool scores; future research in HNC should include ongoing discussion and development around robust outcomes tools and data collection.

Clinical Outcomes of Image-Guided Volumetric Modulated Arc Therapy for Total Body Irradiation

Volumetric modulated arc therapy (VMAT)-based total body irradiation (TBI) with image guidance is a novel technique that is increasing in implementation. Compared to conventional TBI, VMAT-TBI offers favorable dose homogeneity, better organ-at-risk sparing, and enhanced patient comfort. However, whether these dosimetric advantages translate to improved clinical outcomes that justify the increased planning and delivery burden is not well understood. Only a single study of clinical outcomes of VMAT-TBI exists in the literature. We present the largest study to date of clinical outcomes of VMAT-TBI. In this IRB-approved retrospective single-institution study, all patients treated with VMAT-TBI conditioning for allogeneic stem cell transplant, per the institution's published protocol, were identified. Dosimetric data were abstracted from the radiation oncology treatment planning system. Clinical data were abstracted from the electronic medical record. The primary outcome was six-month overall survival (6M OS) from the last day of TBI by Kaplan-Meier method. Fifty-five patients (47 adult and 8 pediatric) were treated with VMAT-TBI between June 2020 and December 2022. All patients received conditioning chemotherapy with standard-dose TBI of 12 or 13.2 Gy in 8 twice-daily fractions. The PTV coverage (V95%) mean was 95.3% ± 1.2%. Mean lung dose was 9.5 Gy ± 0.6 for adult patients and 8.4 Gy ± 0.9 for pediatric patients. Mean lung dose rate was 18.0 cGy/min ± 4.4. Mean kidney dose was 5.9 Gy ± 0.6. Mean skin dose measured by MOSFET was 12.7 Gy ± 1.2. Median treatment time was 63 minutes (range: 53-104). Median follow-up was 7.7 months. At most recent follow-up, 78% of patients were alive. 6M OS was 82%. Common acute toxicities were fatigue (90.9% of patients, all grade 1-2), diarrhea (70.9%, all grade 1-2), nausea (76.4%, all grade 1-2), mucositis (60% grade 1-2, 12.7% grade 3, 1.8% grade 4, no grade 5), and xerostomia (54.5%, all grade 1). Mean pretreatment FEV1 was 98.3 percent of predicted (%p) ± 11.9%p and mean posttreatment FEV1 was 94.7%p ± 13.8%p. Mean pretreatment GFR was 101.4mL/min/1.73m² ± 17.4, mean 3-month posttreatment GFR was 92.4 ± 20.0, and mean 6-month posttreatment GFR was 97.5 ± 26.48. One patient experienced grade 2 pneumonitis; there were no other cases of pneumonitis. There were no acute grade 3+ toxicities aside from mucositis. Observed late toxicities were cataracts (7.3%, all grades 1-3) and hypothyroidism (12.7%, all grades 1-2). There were no grade 3+ late toxicities. Mild acute graft-versus-host disease (GVHD) was noted in 27.2% of patients and mild chronic GVHD was noted in 14.5% of patients, with no other cases of GVHD. In the largest series to date, VMAT-TBI had excellent oncologic and toxicity outcomes. A randomized trial of VMAT-TBI versus standard TBI is warranted.

The dosimetric underpinning of bladder filling criteria for prostate image-guided volumetric modulated arc therapy.

Repeated CT simulation imaging is common at our institution due to failure to achieve acceptable bladder filling in patients undergoing prostate radiotherapy. There is operational value in re-assessing the validity of the bladder filling assessment criteria by comparing the quality of two plans optimized based on either an "Accepted" or "Rejected" bladder status. Twenty prostate patients with repeated CT simulation imaging were included. For each patient, a VMAT plan created using the "Rejected" bladder was compared with the "Accepted" bladder plan. Then, delivered dose to bladder was estimated using ≥4 CBCTs to measure number of fractions with major bladderdose violation (>5% difference) for both plans. Bladder heights of fractions without major bladder dose violations were compared to those with a violation to determine a threshold height for bladder filling acceptability. Using the "Accepted" bladder plans for treatment resulted in 30/175 fractions with major dose violations. These 30 bladders were significantly shorter than those without major violation (mean 28 vs 43mm, p < 0.05). The "Rejected" bladder plans delivered a lower dose to the bladder by ≥5% than the '"Accepted" bladder plans in 59% of fractions, and the number of fractions with major dose violations was 17. Using a shorter bladder for plan optimization resulted in better bladder sparing during treatment and improved compliance to protocol specific bladder dose constraints. A bladder height range of 20-40 mm measured between the bladder dome and the superior aspect of the symphysis pubis is recommended for prostate radiotherapy requiring a full bladder protocol. Using real patient data from simulation and treatment, this study established a range of bladder height that can be measured easily in a clinical setting for assessing adequacy of bladder filling for prostate radiotherapy.

Prostate Cancer Treatment-Related Toxicity: Comparison between 3D-Conformal Radiation Therapy (3D-CRT) and Volumetric Modulated Arc Therapy (VMAT) Techniques.

Objective: This paper illustrates the results of a mono-institutional registry trial, aimed to test whether gastrointestinal (GI) and genitourinary (GU) toxicity rates were lower in localized prostate cancer patients treated with image-guided volumetric modulated arc therapy (IG-VMAT) compared to those treated with IG-3D conformal radiation therapy (IG-3DCRT). Materials and Methods: Histologically proven prostate cancer patients with organ-confined disease, treated between October 2008 and September 2014 with moderately hypofractionated radiotherapy, were reviewed. Fiducial markers were placed in the prostate gland by transrectal ultrasound guide. The prescribed total dose was 70 Gy in 28 fractions. The mean and median dose volume constraints for bladder and rectum as well as total volume of treatment were analyzed as potentially prognostic factors influencing toxicity. The Kaplan−Meier method was applied to calculate survival. Results: Overall, 83 consecutive patients were included. Forty-two (50.6%) patients were treated with 3D-CRT and 41 (49.4%) with the VMAT technique. The median follow-up for toxicity was 77.26 months for the whole cohort. The VMAT allowed for a dose reduction to the rectum and bladder for the large majority of the considered parameters; nonetheless, the only parameter correlated with a clinical outcome was a rectal dose limit V66 > 8.5% for late GI toxicity G ≥ 2 (p = 0.045). Rates of G ≥ 2 toxicities were low among the whole cohort of these patients treated with IGRT. The analysis for rectum dose volume histograms (DVHs) showed that a severe (grade ≥ 2) late GI toxicity was related with the rectal dose limit V66 > 8.5% (p = 0.045). Conclusions: This study shows that moderate hypofractionation is feasible and safe in patients with intermediate and high-risk prostate cancer. Daily IGRT may decrease acute and late toxicity to organs at risk and improve clinical benefit and disease control rate, cutting down the risk of PTV geographical missing. The adoption of VMAT allows for promising results in terms of OAR sparing and a reduction in toxicity that, also given the small sample, did not reach statistical significance.

Radiobiological analysis of preliminary results of a phase II study of pelvic hypofractionated and accelerated radiotherapy for high-risk prostate cancer patients.

PurposeConventionally fractionated radiotherapy (CRT) is widely applied for the treatment of high-risk prostate cancer. Pelvic node irradiation improves control of the disease. Although the therapeutic guidelines support the use of hypofractionated and accelerated radiotherapy (HypoAR), this is addressed to prostate and seminal vesicles. At the same time, the safety and efficacy of HypoAR for pelvic node irradiation remain obscure.Material and MethodsIn a phase II study, we evaluated the feasibility of pelvic HypoAR in 22 high-risk prostate cancer patients. The RT scheme delivers 14 consecutive fractions of 3.67 Gy (total 51.38 Gy) to the prostate, 3.5 Gy (total 49 Gy) to the seminal vesicles, and 2.7 Gy (total 37.8 Gy) to the lymph nodes, using image-guided volumetric modulated arc therapy. A comparative radiobiological analysis of dose-volume histogram is performed (HypoAR vs. hypothetical equivalent CRT regimens, without and with time correction).ResultsOur clinical experience shows impressively low early and short-term late toxicities, without any grade III events, within a median follow-up of 30 months. Only one biochemical relapse was recorded 30 months after irradiation. In radiobiological analysis, considering an α/β-value of 4 Gy and a λ-value of 0.2 Gy/day for late effects, all comparisons predicted significantly lower toxicity for the HypoAR regimen (p < 0.05). For early toxicities (α/β = 10 Gy), a λ-value lower than 0.4 Gy/day favors the HypoAR regimen, which is along with the clinical results.ConclusionRadiobiological analysis favors HypoAR as a safe and effective regimen for high-risk prostate cancer patients, which is confirmed in the current phase II clinical study.

Image-Guided Volumetric Modulated Arc Therapy for Total Body Irradiation: A Single Institution Experience

<h3>Purpose/Objective(s)</h3> The use of multi-isocentric volumetric mediated arc therapy (VMAT) for total body irradiation (TBI) improves dose uniformity and organ-at-risk avoidance and offers better patient comfort, but is limited by time-intensive planning and positioning errors at treatment delivery. We present a system that utilizes automated contouring and planning scripts run in widely-available software combined with image-guided delivery for an efficient simulation-to-treatment workflow. We hypothesize that this system will improve target dose coverage and normal tissue avoidance compared to conventional TBI. <h3>Materials/Methods</h3> Patients were simulated supine in both head-first and feet-first positions. Automated planning software scripts were used to co-register the two simulation scans into a single whole-body CT, to contour organs at risk and planning target volume (PTV), to divide the PTV into sub-targets with junction region overlap, and to place isocenters. Treatment was planned with VMAT for the entire body except for legs and feet, which were planned with conventional AP/PA fields. Image guidance was used for treatment delivery. Plans were evaluated for quality, planning time, delivery time, and setup accuracy. The dosimetric parameters of VMAT-TBI plans versus conventional AP/PA TBI plans were compared. <h3>Results</h3> Twelve patients were simulated and treated with VMAT-TBI: three pediatric patients and nine adult patients (age range: 9-59). Compared with conventional whole-body AP/PA technique, VMAT-TBI improved dose coverage to the whole body: PTV V₁₀₀ was improved from 71.4% ± 11.1% to 88.1% ± 2.6% (<i>P</i> < 0.001). Mean lung dose was reduced from 11.1 Gy ± 0.9 Gy to 9.3 Gy ± 1.0 Gy (<i>P</i> < 0.001). With a beam monitor unit (MU) rate of 200 MU/minute, mean lung dose rate was 15.5 centiGray (cGY)/minute. Robust planning and image-guided delivery reduced setup uncertainty. VMAT-TBI planning time was one working day. Total time on the treatment table was approximately one hour per fraction. All patients were able to complete the treatment course as prescribed. <h3>Conclusion</h3> A robust treatment planning technique and an image-guided delivery workflow were developed for VMAT-TBI. Planning efficiency was improved using automation with scripts, making planning time comparable to traditional TBI. Compared with classic AP/PA whole body fields, VMAT-TBI improved whole body prescription dose coverage and lung sparing. Time on treatment table was comparable to treatment time for traditional TBI, and patient comfort was improved due to ability to deliver treatment in the supine position. VMAT planning should be considered for all myeloablative transplant protocol patients being treated with TBI.

How Much Daily Image-guided Volumetric Modulated Arc Therapy Is Useful for Proctitis Prevention With Respect to Static Intensity Modulated Radiotherapy Supported by Topical Medications Among Localized Prostate Cancer Patients?

To evaluate if topical support therapy during static-intensity modulated radiotherapy (sIMRT) course is able to equal the characteristic minimum risk for radiation proctitis of Image-guided volumetric modulated arc therapy (IG-VMAT) treatment among localized prostate cancer patients. Rectal toxicity data of the above patients were retrospectively collected throughout three different clinical periods at our Radiotherapy Deparment: from October 2011 to December 2012, prostate cancer patients were treated with sIMRT and in advance supported by means of daily topical corticosteroids; from January 2013 to November 2016, topical corticosteroids were replaced by daily hyaluronic acid enemas; from December 2016 to May 2018 eligible patients were treated with newly introduced IG-VMAT supported by only on-demand topical corticosteroids. Among 359 eligible patients, IG-VMAT was proven generally more effective than sIMRT supported by topical medications in terms of proctitis reduction, although without clinical and practical relevance. Topical medications might have a role in radiation proctitis prevention.

Efficacy and Safety of Image-Guided Intensity-Modulated Radiation Therapy and Volumetric Modulated Arc Therapy Combined with Paclitaxel Liposomes and Cisplatin for Locally Advanced Stage IIB-IIIB Cervical Cancer: A Retrospective Study at a Single Center.

BackgroundThis retrospective study aimed to investigate the efficacy and safety of image-guided intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) combined with administration of paclitaxel liposomes and cisplatin for locally advanced stage IIB–IIIB cervical cancer at a single center in China.Material/MethodsThe clinical data of 126 patients with stage IIB–IIIB cervical cancer treated in our hospital were retrospectively analyzed. The patients were divided into the IMRT group (n=63) and the VMAT group (n=63). The short-term clinical efficacy, the incidence of adverse reactions, the quality-of-life score, and the changes in levels of T-lymphocyte subsets, serum inflammatory factors, and tumor markers were compared pre- and posttreatment between the 2 groups.ResultsThe clinical response rate was 90.5% and 96.8% in the IMRT group and the VMAT group, respectively; the difference was not statistically significant. After treatment, the levels of CD3+, CD4+, and CD4+/CD8+ subsets rose significantly, while the CD8+ level declined significantly in both groups compared with the pretreatment levels. After treatment, the levels of serum vascular endothelial growth factor, squamous cell carcinoma antigen, interleukin-8, tumor necrosis factor-α, carcinoembryonic antigen, and carbohydrate antigen 125 declined in both groups compared with pretreatment levels. After treatment, the Karnofsky performance scale score rose in both groups, and it was higher in the VMAT group than in the IMRT group.ConclusionsIMRT and VMAT combined with paclitaxel liposomes and cisplatin have similar short-term clinical efficacy and long-term survival rates in the treatment of stage IIB–IIIB cervical cancer.

Moderately hypofractionated radiotherapy for localized prostate cancer: updated long-term outcome and toxicity analysis

PurposeEvaluation of long-term outcome and toxicity of moderately hypofractionated radiotherapy using intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost treatment planning and cone beam CT-based image guidance for localized prostate cancer.MethodsBetween 2005 and 2015, 346 consecutive patients with localized prostate cancer received primary radiotherapy using cone beam CT-based image-guided intensity-modulated radiotherapy (IG-IMRT) and volumetric modulated arc therapy (IG-VMAT) with a simultaneous integrated boost (SIB). Total doses of 73.9 Gy (n = 44) and 76.2 Gy (n = 302) to the high-dose PTV were delivered in 32 and 33 fractions, respectively. The low-dose PTV received a dose (D95) of 60.06 Gy in single doses of 1.82 Gy. The pelvic lymph nodes were treated in 91 high-risk patients to 45.5 Gy (D95).ResultsMedian follow-up was 61.8 months. The 5‑year biochemical relapse-free survival (bRFS) was 85.4% for all patients and 93.3, 87.4, and 79.4% for low-, intermediate-, and high-risk disease, respectively. The 5‑year prostate cancer-specific survival (PSS) was 94.8% for all patients and 98.7, 98.9, 89.3% for low-, intermediate-, and high-risk disease, respectively. The 5‑year and 10-year overall survival rates were 83.8 and 66.3% and the 5‑year and 10-year freedom from distant metastasis rates were 92.2 and 88.0%, respectively. Cumulative 5‑year late GU toxicity and late GI toxicity grade ≥2 was observed in 26.3 and 12.1% of the patients, respectively. Cumulative 5‑year late grade 3 GU/GI toxicity occurred in 4.0/1.2%.ConclusionModerately hypofractionated radiotherapy using SIB treatment planning and cone beam CT image guidance resulted in high biochemical control and survival with low rates of late toxicity.

Analysis of long-term outcome of image-guided volumetric modulated arc therapy (VMAT) for primary malignant tumor of the cervical spine

ABSTRACT Objective Retrospective analysis of the long-term clinical outcome and acute toxicity of the primary malignant tumor of cervical spine receiving CBCT image-guided VMAT. Methods Thirty patients with primary malignant tumor of the cervical spine included in our center, from December 2013 to January 2016, 28 patients were retrospectively studied. The prescription dosage 95% PTV volume dose was 44 Gy, 2.0 Gy/fraction, and a total of 22 times. The median PGTV synchronized volume dose was 60 Gy (45–62.1 Gy), median 2.5 Gy (2–2.7 Gy)/fraction. In volumetric modulated, two arc volumetric modulated arc therapy (VMAT) was used, with spinal cord dosage DMAX< 45 Gy. Early response rate and acute toxicities were analyzed. Result The follow-up duration was 6–76 months (median 53 months). At the end of follow-up of June 1, 2019, 78.6% (22/28) patients were still alive. 3 and 5-y local control rates were 67.3% and 56.5% while 3 and 5-y OS were both 78.6% in the whole group of patients, respectively. Fourteen patients with chordoma 5-y local control rates and OS were 57.1% and 85.7%, respectively. Nine patients with giant-cell tumor of bone had a 5-y local control rate and OS were 77.8% and 85.7%, respectively. The response rate for moderate pain or above was 80% (8/10). Eleven patients (39.3%) suffered from grade 1 acute skin toxicity. Twenty-four patients (85.7%) had grade 1/2 mucositis. No radiation-induced spinal cord injury was found. Conclusion The image-guided VMAT for primary malignant tumor of the cervical spine provided a satisfactory long-term local control rate.

Late gastrointestinal toxicity after radiotherapy for rectal cancer: a systematic review.

Although the multimodal cancer treatment techniques have greatly improved over the years, irradiation-induced late gastrointestinal toxicity remains a great concern as it may highly affect the quality of life of a patient. The aim of this study was to define the prevalence of late gastrointestinal toxicities. Electronic databases of Cochrane Library, Embase, Web of Science, CENTRAL and PubMed were searched until September 2019. We used the following keywords: radiotherapy, radiation therapy, irradiation, rectal cancer, gastrointestinal toxicity, adverse effects, late effects, pelvic radiation and pelvic radiation disease. Nine studies were included into this review out of 4785 that were preidentified as potentially relevant. Overall prevalence of severe (Grade 3 or higher) late irradiation-induced gastrointestinal toxicities was up to 19%. Most frequent toxicities of any grade were reported to be diarrhoea (up to 35%), faecal incontinence (22%), incontinence to gas (71%), rectal bleeding (9%), rectal pain (13%) and obstruction (7.4%). Preoperative treatment approaches and more advance radiotherapy techniques such as intensity-modulated and image-guided radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) turn out to result in lower late gastrointestinal toxicity rates. After great improvements in rectal cancer treatment, late gastrointestinal toxicity after radiotherapy is experienced less frequent and less severe; however, it remains a great concern associated with worse quality of life.

Moderately HRT vs. CRT for localized prostate cancer using image-guided VMAT with SIB: evaluation of acute and late toxicities

PurposeThis retrospective study aims at investigating the effects of moderately hypofractionated radiation therapy (HRT) on acute and late toxicities as well as on early biochemical control and therapeutic efficiency compared to conventional radiation therapy (CRT) in prostate cancer.Patients and methodsWe analyzed 55 HRT patients irradiated with the total dose of 60 Gy in 20 fractions delivered over 4 weeks. These patients were compared to a control group of 55 patients who received CRT with a total of <78 Gy in 37–39 fractions delivered over circa 8 weeks. External beam radiation therapy (EBRT) was conducted using daily image-guided (cone beam CT) volumetric modulated arc therapy (VMAT) and a simultaneously integrated boost (SIB) for both groups to protect the rectum. Acute toxicities were evaluated according to Common Terminology Criteria for Adverse Events (CTCAE) v5, whereas chronic toxicities were assessed in accordance with LENT-SOMA. Patient traits were compared by implementing t‑tests and Wilcoxon–Whitney tests for continuous variables, whereas discrete characteristics were evaluated by applying two-tailed Fisher’s exact tests. In addition, we calculated average treatment effects (ATE). Thereby, propensity score matching (PSM) based on nearest-neighbor matching considering age, comorbidities, and risk stratification as covariates was applied. The statistical analysis was conducted using Stata 14.2 (StataCorp LLC, TX, USA).ResultsAs confirmed by the descriptive tests, the ATE revealed that the intensity and occurrence of urinary frequency (p = 0.034) and proctitis (p = 0.027) significantly decreased for the HRT group, whereas all other acute toxicities did not differ significantly between the HRT and CRT groups. For late toxicities, neither statistical tests nor ATE estimation showed significant differences. Also, no significant difference was found regarding the decrease in prostate specific antigen (PSA) after a median follow-up of 13 months (range 2–28 months), which indicates biochemical freedom from progression.ConclusionHRT offers several medical and economic advantages and should therefore be considered as a useful alternative to CRT.

Influence of volumetric modulated arc therapy and FET-PET scanning on treatment outcomes for glioblastoma patients

BackgroundWe sought to assess the influence of the clinical introduction of new radiotherapy technologies on glioblastoma patients’ outcomes. MethodsNewly diagnosed glioblastoma patients treated with 60 Gy and temozolomide (2005–2014) were analyzed. The patients’ GTV and CTV were defined based on MR (n = 521) or FET-PET/MR (n = 190), and were treated using conformal radiotherapy (CRT, n = 159) or image-guided volumetric modulated arc therapy with hippocampal sparing (IG-VMAT, n = 362). Progression-free survival (PFS) was assessed using the McDonald criteria. Associations between clinical data, dosimetry data, treatment technology, for PFS and overall survival (OS) were explored. ResultsThe PFS (7 months) and OS (15 months) were unaffected by CRT, IG-VMAT and FET-PET technology. Mean brain dose was correlated with tumor volume, and was lower for IG-VMAT vs. CRT (p < 0.001). Larger mean brain dose was associated with inferior PFS (univariate/multivariate Cox models, p < 0.001) and OS (univariate, p < 0.001). Multivariate Cox models revealed association of larger mean brainstem dose (p < 0.001), BTV (p = 0.045), steroid use at baseline (p = 0.003), age (p = 0.019) and MGMT status (p = 0.022) with lower OS. ConclusionsIntroduction of hippocampal-sparing IG-VMAT technology appeared to be safe, and may have reduced toxicity and cognitive impairment. Larger mean brain dose was strongly associated with inferior PFS and OS.

The impact of margin reduction on outcome and toxicity in head and neck cancer patients treated with image-guided volumetric modulated arc therapy (VMAT)

Background and purposeIn recent decades, outcomes of patients with head and neck cancer (HNC) have improved as a result of implementing several strategies, such as chemoradiation. However, these improvements were achieved at the cost of increased toxicity. One way to reduce radiation-related toxicity is by reducing the margins. Materials and methodsBetween 2013 and 2016, 206 consecutive patients were treated with CTV-PTV margin of 5 mm and subsequently 208 patients with 3 mm margin. This study evaluates the impact of reducing clinical target volume (CTV) to planning target volume (PTV) margin on outcome and toxicity. ResultsAll patients were treated with volumetric modulated arc therapy (VMAT) with daily-image guidance using cone-beam CT (CBCT). Overall acute grade 3 toxicity was significantly lower in 3 mm-group, compared to 5 mm-group (53.8% vs. 65%, respectively, p = 0.032). The same was true for acute grade 3 mucositis (30.8% vs. 42.2%, p = 0.008) and for acute grade 3 dysphagia (feeding tube-dependence) (22.1% vs. 33.5%, p = 0.026). The incidence of ongoing feeding tube-dependence after 3 months of radiotherapy was 11.1% and 20.4%, respectively (p = 0.012). The 2-year incidence of late grade ≥2 xerostomia was 15.8% and 19.4% (p = 0.8). The 2-year loco-regional control rates of patients treated in 3 mm and 5 mm-groups were 79.9% and 79.2% (p = 1.0). The figures for disease-free survival were 71.5% and 72.7 (p = 0.6) and for overall survival were 75.2% and 75.1% (p = 0.9). ConclusionReducing the CTV-PTV margin from 5 to 3 mm combined with daily CBCT-guided VMAT reduced the severity, frequency, and duration of radiation-related toxicity without jeopardizing outcome.

Analysis of adverse events after radiotherapy for primary and metastatic prostate carcinoma in patients with oligometastasized castration resistant prostate carcinoma

Objective To analyze the adverse events in patients diagnosed with oligometastasized castration resistant prostate carcinoma (CRPC) receiving radiotherapy for the primary and metastatic prostate carcinomas. Methods Twenty patients with oligometastasized CRPC admitted to our hospital between 2011 and 2015 were treated with image-guided volumetric modulated arc therapy (VMAT). The dose for prostate+ seminal vesicle was 76 Gy/38 f, 46 Gy/23 f for the pelvic lymph node and the median dose for the metastatic lesions was 60 Gy (52-66)/23 f. Relevant clinical data and adverse events were analyzed. Results All patients completed the radiotherapy. Only 1 patient showed grade Ⅲ urinary obstruction and received catheterization. In terms of acute adverse events of ≥ grade Ⅱ, urinary tract was observed in 4 cases (20%), rectum in 2(10%) and blood system in 2(10%). The rectal V50 was correlated with acute adverse events of ≥ grade Ⅱ. The median follow-up time was 24.2 months. No patient suffered from late adverse events of ≥ grade Ⅱ. All cases showed a decline in the level of prostate specific antigen (PSA) after radiotherapy. The median PSA reduction rate was 99%. Among them, 16 cases (80%) had a PSA reduction rate of over 90%. Conclusions It is safe and efficacious to perform radical dosage radiotherapy for primary and metastatic prostate carcinomas in patients with oligometastasized CRPC. Key words: Castration resistant prostate carcinoma/volumetric modulated arc therapy; Oligometastasis; Adverse event

Early Clinical Outcomes, Patterns of Failure, and Acute Haematologic Toxicity of Image-Guided Volumetric Modulated Arc Therapy (IG-VMAT) in the Definitive Treatment of Locally Advanced Carcinoma Cervix.

Purpose:To evaluate clinical outcomes and failure patterns in patients with locally advanced cervical cancer (LACC) treated definitively using image-guided volumetric-modulated arc therapy (IG-VMAT).Methods and materials:This retrospective review included 18 consecutively treated patients with LACC. Treatment consisted of IG-VMAT and concurrent chemotherapy followed by intracavitary radiotherapy. The primary end points were overall survival (OS) and disease-free survival (DFS). Acute haematologic toxicity was evaluated using Radiation Therapy Oncology Group (RTOG) criteria.Results:A total of 16 patients were either stage IIB or IIIB and the median follow-up was 30.5 months (interquartile range: 13-36.25 months). The 2-year DFS was 63.3% (95% confidence interval [CI]: 52.8%-72.4%) and 2-year OS was 72.2% (95% CI: 62.1%-80.5%). There were 7 treatment failures, predominantly in-field. Acute haematologic toxicity was low.Conclusions:IG-VMAT is associated with favourable outcomes for patients with LACC.

One-Size Does Not Fit All: Planning Objectives with IG-VMAT for Oropharynx Cancer and Guidelines By Clinical Context

Protocols set static objectives to organs-at-risk (OARs) to provide guidance during radiation treatment planning for oropharynx cancer (OPC). However, these objectives are dependent on the clinical scenario and may be either easily achieved or unrealistic based on disease anatomic distribution. Here we correlate clinical parameters with dosimetric achievements in the VMAT era and identify achievable objectives for various scenarios. Patients treated non-operatively with narrow-margin, image-guided volumetric modulated arc therapy (IG-VMAT) for squamous OPC were identified from an IRB-approved registry. Narrow-margin was defined as a routine 2-3 mm expansion from GTV to CTV and another 2-3 mm expansion from CTV to PTV, with manual edits as per physician preference. Patients treated with static IMRT were excluded due to superior planning achievements with VMAT. Patients were treated to doses of 66-72 Gy to PTVHD with an elective dose of 54-56 Gy to PTVLD. Patients treated to doses of 60 Gy to PTVHD on protocol were excluded. All normal tissue doses were re-normalized to a PTVHD of 70 Gy. Dosimetric data was extracted via automated scripting using MIM Software (Cleveland, OH). Three treatment groups were correlated with dosimetric achievements: unilateral neck with cT1-2N0-2b; bilateral neck with cT1-2N0-2b, and bilateral neck with cT3-4 or N2c-3. Planning objectives achievable in 75% of cases were described for each treatment group. 79 patients were included. The primary site originated from the base of tongue in 56%, tonsil in 39% and other OPC sites in 5%. 90% were node-positive. The bilateral neck was involved in 30% and 3% were N3. The unilateral neck was targeted in 15% and bilateral neck in 85%. The PTVHD was midline in 28% and lateralized in 72%. In each case, PTVHD achieved a D95>97%. Tumor laterality was correlated with mean dose to midline structures such as the posterior pharyngeal wall, supraglottis, glottis and oral cavity (Wilcoxon p£0.01 for all). Mean doses achievable in 75% of cases were 39, 50 and 53 Gy for the posterior pharyngeal wall, 27, 47 and 54 Gy for the supraglottis, 32, 37 and 67 Gy for the oral cavity, 21, 30 and 32 Gy for the glottis, and 15, 41 and 67 Gy for the contralateral submandibular for the unilateral cT1-2N0-2b, bilateral cT1-2N0-2b, and bilateral cT3-4 or N2c-3 groups respectively. Among each dose group, the 90% range was >20 Gy for nearly every structure, suggesting significant heterogeneity. Treatment planning for OPC is heterogeneous. Achievement of static published dose objectives is not always possible but also does not ensure quality. Physicians should individualize planning objectives and planners should push for the lowest achievable doses to OARs. OAR doses routinely achieved for three clinical groups treated with IG-VMAT are provided for reference.

Treatment plan comparison between Tri-Co-60 magnetic-resonance image-guided radiation therapy and volumetric modulated arc therapy for prostate cancer.

To investigate the plan quality of tri-Co-60 intensity-modulated radiation therapy (IMRT) with magnetic-resonance image-guided radiation therapy compared with volumetric-modulated arc therapy (VMAT) for prostate cancer. Twenty patients with intermediate-risk prostate cancer, who received radical VMAT were selected. Additional tri-Co-60 IMRT plans were generated for each patient. Both primary and boost plans were generated with tri-Co-60 IMRT and VMAT techniques. The prescription doses of the primary and boost plans were 50.4 Gy and 30.6 Gy, respectively. The primary and boost planning target volumes (PTVs) of the tri-Co-60 IMRT were generated with 3 mm margins from the primary clinical target volume (CTV, prostate + seminal vesicle) and a boost CTV (prostate), respectively. VMAT had a primary planning target volume (primary CTV + 1 cm or 2 cm margins) and a boost PTV (boost CTV + 0.7 cm margins), respectively. For both tri-Co-60 IMRT and VMAT, all the primary and boost plans were generated that 95% of the target volumes would be covered by the 100% of the prescription doses. Sum plans were generated by summation of primary and boost plans. In sum plans, the average values of V70 Gy of the bladder of tri-Co-60 IMRT vs. VMAT were 4.0% ± 3.1% vs. 10.9% ± 6.7%, (p < 0.001). Average values of V70 Gy of the rectum of tri-Co-60 IMRT vs. VMAT were 5.2% ± 1.8% vs. 19.1% ± 4.0% (p < 0.001). The doses of tri-Co-60 IMRT delivered to the bladder and rectum were smaller than those of VMAT while maintaining identical target coverage in both plans.

Radiothérapie des cancers de l’œsophage, du cardia et de l’estomac

Localized oesophageal and gastric cancers have a poor prognosis. In oesophageal cancer, external radiotherapy combined with concomitant chemotherapy is accepted as part of the therapeutic armamentarium in a curative intent in the preoperative setting for resectable tumours; or without surgery in inoperable patients or non-resectable tumours due to wide local and/or regional extension. Data from the literature show conflicting results with no clinical evidence in favour of either a unique dose protocol or consensual target volume definition in the setting of exclusive chemoradiation. In the preoperative setting, chemoradiotherapy has become the standard in oesophageal cancer, even though there is no evidence that surgery may be beneficial in locally advanced tumours that respond to radiotherapy and chemotherapy. The main cause of failure after exclusive chemoradiotherapy in oesophageal cancer is locoregional relapse suggesting that doses and volumes usually considered may be inadequate. In gastric cancer, radiotherapy may be indicated postoperatively in patients with resected tumours that include less than D2 lymph node dissection or in the absence of perioperative chemotherapy. Preoperative chemoradiotherapy in gastric cancers is still under investigation. The evolving techniques of external radiotherapy, such as image-guided radiotherapy (IMRT) and volumetric modulated arctherapy (VMAT) have reduced the volume of lung and heart exposed to radiation, which seems to have diminished radiotherapy-related morbi-mortality rates. Given this, quality assurance for radiotherapy and protocols for radiotherapy delivery must be better standardized. This article on the indications for radiotherapy and the techniques used in oesophageal and gastric cancers is included in a special issue dedicated to national recommendations from the French society of radiation oncology (SFRO) on radiotherapy indications, planning, dose prescription, and techniques of radiotherapy delivery.

P-217 Chemoradiotherapy with Image-Guided Volumetric Modulated Arc Therapy (IG-VMAT) and Image-Guided Intensity Modulated Radiotherapy (IG-IMRT) to treat Squamous Anal Cancer

P-217 Chemoradiotherapy with Image-Guided Volumetric Modulated Arc Therapy (IG-VMAT) and Image-Guided Intensity Modulated Radiotherapy (IG-IMRT) to treat Squamous Anal Cancer