3D Conformal Radiotherapy Research Articles

Abstract P1-10-18: Impact of Adjuvant Chemoradiation on cardiopulmonary function and Quality of Life in Breast Cancer

Abstract Aims and Objectives – To evaluate the safety of adjuvant chemo-radiation (CTRT) for breast cancer. We report the cardio-pulmonary safety and quality of life outcome of this regimen. Methods – Stage II-III invasive breast cancer patients planned for adjuvant taxane-based chemotherapy and adjuvant radiotherapy (RT) between April 2019 to December 2020 were eligible irrespective of prior neo-adjuvant therapy. Patients received standard 3D conformal radiotherapy (40 Gy in 15 fractions over 3 weeks ± boost for breast conservation) along with the third cycle of adjuvant taxanes in a 3- weekly schedule or the eighth cycle in a weekly schedule. Troponin T, echo cardiography and pulmonary function test were done pre-RT and repeated at 6 months from RT conclusion while quality of life was evaluated pre-RT, at RT conclusion and after 6 months using EORTC QLQ C30 and BR23. Results – Sixty patients were analysed. The median ejection fraction pre and post CTRT was 60% (p=0.177). The median value of Troponin T at baseline was 37 which decreased to 20 post CTRT (p=0.009). Of the 54 patients who underwent the PFT, the functional vital capacity (FCV) was 2.29 litres at baseline which was 2.2 litres post CTRT (p=0.375). No significant difference was seen for forced expiratory volume (FEV) at 1 second (1.86 vs. 1.82: p=0.365), FEV1/FVC (81.5 vs. 81.43; p=0.9) and diffusing capacity for carbon monoxide (DLCO) (88.3 vs. 87.6; p=0.62) at baseline and post CTRT respectively. There was a significant improvement in QOL scores for nausea, vomiting, pain, constipation, loss of appetite and hair loss post RT 6 months. Conclusion- Patients treated with taxane-based adjuvant CTRT had stable cardio-pulmonary profile at 6 months compared to pre-RT. Quality of life scores improved after treatment for most of the domains compared to the pre-RT scores. Table 1. Calculated scores of EORTC QLQ-C30 and BR23 scales for breast cancer patients at baseline, post CTRT and at first follow up of six months. Citation Format: AKANKSHA ANUP, Tabassum Wadasadawala, CARLTON JOHNNY, RAJIV SARIN, RIMA PATHAK, REVATHY KRISHNAMURTHY, Sudeep Gupta, VANI PARMAR, Jaya Ghosh, JYOTI BAJPAI, SEEMA GULIA. Impact of Adjuvant Chemoradiation on cardiopulmonary function and Quality of Life in Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-10-18.

Metastatic cutaneous squamous cell carcinoma to the parotid: Adjuvant radiotherapy and treatment outcomes.

Adjuvant radiotherapy is an established component in the management of metastatic cutaneous squamous cell carcinoma (SCC) involving the parotid gland. Radiotherapy technique, dose and volumes are seldom described sufficiently to allow close examination. We report our treatment outcomes and focus on treatment-related factors that affect outcomes in this cohort. We performed a retrospective review of patients with metastatic cutaneous SCCs who underwent parotidectomy with or without ipsilateral neck dissection. All patients received adjuvant radiotherapy. Demographics, clinical data and treatment details were collected from an intuitional electronic database. Individual patient-level radiotherapy technique, volumes and doses were reviewed. Between July 2008 and July 2018, 60 patients met our inclusion criteria. Median follow-up duration was 32.7 months. The mean age was 66.4 years. The majority of patients (49 patients) received full neck irradiation. The 2-year and 5-year loco-regional failure-free survival was 87% (95% confidence interval (CI): 0.74-0.93) and 71% (95% CI: 0.52, 0.83), respectively. The 2-year and 5-year overall survival was 76% (95% CI: 0.62, 0.85) and 60% (95% CI: 0.45, 0.72), respectively. There were 15 cases of loco-regional failures, with 6 cases with dermal involvement. Lymphovascular invasion (LVI) was associated with higher loco-regional failure (hazard ratio: 8.43, 95% CI: 1.85-38.39, P =0.005) and cancer-specific mortality (hazard ratio: 5.40, 95% CI: 1.40-20.87, P=0.015). Treatment technique, intensity-modulated radiation therapy (IMRT) vs 3D conformal radiotherapy (3D CRT), bolus use, perineural invasion (PNI) and surgical margins were not significantly associated with loco-regional failure. We demonstrated high loco-regional control rates with routine use of comprehensive adjuvant radiotherapy. The presence of LVI was identified as a strong predictor for recurrence. Further analysis will help to define optimal radiation dose and techniques.

Characterization of the Response of 9L and U-251N Orthotopic Brain Tumors to 3D Conformal Radiation Therapy.

In a study employing MRI-guided stereotactic radiotherapy (SRS) in two orthotopic rodent brain tumor models, the radiation dose yielding 50% survival (the TCD50) was sought. Syngeneic 9L cells, or human U-251N cells, were implanted stereotactically in 136 Fischer 344 rats or 98 RNU athymic rats, respectively. At approximately 7 days after implantation for 9L, and 18 days for U-251N, rats were imaged with contrast-enhanced MRI (CE-MRI) and then irradiated using a Small Animal Radiation Research Platform (SARRP) operating at 220 kV and 13 mA with an effective energy of ∼70 keV and dose rate of ∼2.5 Gy per min. Radiation doses were delivered as single fractions. Cone-beam CT images were acquired before irradiation, and tumor volumes were defined using co-registered CE-MRI images. Treatment planning using MuriPlan software defined four non-coplanar arcs with an identical isocenter, subsequently accomplished by the SARRP. Thus, the treatment workflow emulated that of current clinical practice. The study endpoint was animal survival to 200 days. The TCD50 inferred from Kaplan-Meier survival estimation was approximately 25 Gy for 9L tumors and below 20 Gy, but within the 95% confidence interval in U-251N tumors. Cox proportional-hazards modeling did not suggest an effect of sex, with the caveat of wide confidence intervals. Having identified the radiation dose at which approximately half of a group of animals was cured, the biological parameters that accompany radiation response can be examined.

Different meaning of the mean heart dose between 3D-CRT and IMRT for breast cancer radiotherapy.

Previous studies in 2D and in 3D conformal radiotherapy concludes that the maximal heart distance and the mean heart dose (MHD) are considered predictive of late cardiac toxicities. As the use of inverse-planned intensity modulated radiation therapy (IMRT) is increasing worldwide, we hypothesized that this 3D MHD might not be representative of heart exposure after IMRT for breast cancer (BC). Patients with left-sided BC and unfavorable cardiac anatomy received IMRT. Their treatment plan was compared to a virtual treatment plan for 3D conformal radiotherapy with similar target volume coverage (study A). Then, a second 3D conformal treatment plan was generated to achieve equivalent individual MHD obtained by IMRT. Then the heart and left anterior descending (LAD) coronary artery exposures were analyzed (study B). Last, the relationship between MHD and the heart volume or LAD coronary artery volume receiving at least 30Gy, 40Gy and 45Gy in function of each additional 1Gy to the MHD was assessed (study C). A significant decrease of heart and LAD coronary artery exposure to high dose was observed with the IMRT compared with the 3D conformal radiotherapy plans that both ensured adequate target coverage (study A). The results of study B and C showed that 3D MHD was not representative of similar heart substructure exposure with IMRT, especially in the case of high dose exposure. The mean heart dose is not a representative dosimetric parameter to assess heart exposure following IMRT. Equivalent MHD values following IMRT and 3DRT BC treatment do not represent the same dose distribution leading to extreme caution when using this parameter for IMRT plan validation.

Toxicity Profile of Intensity Modulated Radiotherapy Vs. 3D-Conformal Radiotherapy in Head and neck cancer: A Retrospective study

Background: Most head and neck patients have historically been treated with photon-based radiation techniques such as intensity modulated radiation therapy (IMRT), there is a growing awareness of the potential clinical benefits of proton therapy over IMRT in the definitive, postoperative and reirradiation settings given the unique physical properties of protons. Aim of the work: to assess toxicity profile of IMRT in comparison to 3D conformal radiotherapy (3DCRT) and to assess predictors for progression free survival and overall survival rates. Patients and Methods: This retrospective cohort study included 131 head and neck cancer patients who were recruited from El Hussein University Hospital over 10 years then they were divided into 2 groups according to the type of radiotherapy. Results: Both groups were comparable regarding age, sex and associated medical disorders except for ischemic heart disease and smoking. Sites of primary tumors were comparable except tongue and nasopharynx. Most of 3DCRT group received TPF as induction chemotherapy and most of IMRT group received concurrent chemotherapy. Dose of irradiation was higher significantly among IMRT group. Grades of early and late toxicity were higher among 3DCRT group. There was no statistically significant difference between both groups regarding response to treatment. Mortality cases were higher significantly among 3DCRT group. Cox regression analysis was performed to assess predictors for progression free survival and overall survival in each group. Conclusion: IMRT provide good choice as radiotherapy technique for head and neck cancers with adequate efficacy similar to other techniques and better toxicity profile.

Comparison of esophagus dose in breast cancer patients undergoing supraclavicular irradiation with and without esophagus countering.

Esophagus toxicity and the risk of esophageal cancer are linked to radiation dose to the esophagus in breast cancer patients undergoing supraclavicular irradiation. The aim of this study was to evaluate the impact of esophagus contouring on the dose received in the esophagus in breast cancer patients undergoing supraclavicular irradiation. This study included 30 treatment plans for breast cancer patients who received 50 Gy/25 fractions (2 Gy/fraction/day) using 3D-conformal radiation therapy (3D-CRT) to the whole breast or chest wall and supraclavicular. Our study included two groups: the non-sparing group was the treatment plan in which the esophagus was not delineated and the esophagus sparing group was generated, in which the plans were modified to spare the esophagus. The maximum dose, mean dose, and percentage of esophagus volume received, 5, 10, 15, and 20 Gy, respectively (V5, V10, V15, and V20), were used to evaluate both groups. One-way analysis of variance was used. A P value <0.05 was considered statistically significant. The esophagus sparing group plans show a reduction in the esophageal mean dose Dmean (5.72 ± 5.15) Gy when compared to the non-sparing group (7.83 ± 3.31) Gy. Likewise, the maximum dose, V5, V10, V15, and V20 were reduced in the esophagus sparing group. All dosimetric parameters were significantly higher (P < 0.05) in patients with left breast cancer for both groups. Our results suggest that it is possible to reduce the dose to the esophagus by considering the esophagus during treatment planning while maintaining plan quality. This reduction could lead to the greatest predicted decrease in acute esophagitis and esophageal cancer.

A Dosimetric Study Comparing Different Radiotherapy Planning Techniques With and Without Deep Inspiratory Breath Hold for Breast Cancer.

To analyze whether deep inspiratory breath hold (DIBH) would be dosimetrically beneficial irrespective of radiotherapy planning techniques for patients with left breast cancers requiring adjuvant radiotherapy. Planning CT scans were taken in free-breathing (FB) as well as deep-inspiration breath hold (DIBH) for patients requiring adjuvant radiotherapy for left breast cancers. After registration, three radiotherapy plans - 3D-conformal radiotherapy (3DCRT), intensity modulated RT (IMRT), and volumetric modulated arc-therapy (VMAT) - were generated for both FB and DIBH scans for each patient. The dose-volume parameters were collected from the dose-volume histogram and analyzed. A paired t-test is used for statistical analysis of the parameters. The study was conducted on thirteen patients. The mean dose of the left lung was reduced with DIBH by 32%, 24%, and 6% (8.6 Gy, 6.6 Gy, and 6.4 Gy) with 3DCRT, IMRT, and VMAT, respectively. The mean heart dose was reduced by 3.3 Gy (2.2 vs 5.5 Gy), 2.2 Gy (7.5 vs 9.7 Gy), and 1.2 Gy (5.8 vs 7 Gy) with 3DCRT, IMRT, and VMAT with DIBH. Similarly, the left anterior descending artery (LAD) mean dose was relatively reduced by 80%, 34%, and 20% when compared with the FB scans for 3DCRT, IMRT, and VMAT respectively, with max dose in the 3DCRT plan. DIBH appears to have maximum benefit in achieving a better sparing of organs-at-risk for patients being considered for 3DCRT, and to a lesser extent with even IMRT and VMAT techniques.

Dosimetric Study Comparing 3D Conformal Radiotherapy (3D-CRT), Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) in Hypofractionated One-Week Radiotherapy Regimen in Breast Cancer.

Introduction Recently, the one-week hypofractionated radiotherapy regimen (26 Gy in 5 fractions) for adjuvant breast radiotherapy has been shown to be non-inferior to other hypofractionated regimens (15-16 fractions). The aim of the present dosimetric study is to compare Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT) and 3D Conformal Radiotherapy (3D-CRT) for a one-week hypofractionated radiotherapy regimen (26 Gy in 5 fractions) for adjuvant breast radiotherapy. Methods A total of 30 patients with histologically proven invasive carcinoma of the breast after breast conservation surgery (BCS) or modified radical mastectomy (MRM) were considered for in silico planning study. The dose prescription used was 26 Gy in 5 fractionsas used in the FAST Forward protocol. Targets were contoured according to standard guidelines. The heart, ipsilateral lung, and contralateral breast were contoured as organs at risk. Results Planning Target Volume (PTV) coverage:For IMRT, VMAT and 3D-CRT, respectively, the volumes that received at least 95% of the prescription dose (V95) were 95.7 ± 2.12, 92.47 ± 3.83, 90.87 ± 5.13; mean PTV doses (Dmean) were 26.1 ± 0.6, 25.7 ± 0.7, and 28 ± 4.39 (3D-CRT has higher Dmean compared to other techniques). Maximum PTV doses (Dmax) were 28.23 ± 0.72, 28.73 ± 0.64, and 29.8 ± 1.03. IMRT had a better V95 coverage and conformity index. Organs At Risk (OARs):The volumes that received at least 25% of the prescription dose (V25) of the heart were 3.41 ± 4.7, 1.8 ± 2.02 and 4.3 ± 6.98 in IMRT, VMAT and 3D-CRT, respectively. The volumetric (V25) comparison of heart dose in left-sided breast cancer was significantly different between VMAT and 3D-CRT (p=0.04, Wilcoxon signed-rank test). The volume that received at least 5% of the prescription dose (V5)was less than 25% in the 3D-CRT plan (12.55).For the ipsilateral lung, the V25 parameters were 19.53 ± 10.96, 23.93 ± 13.58 and 20.5 ± 12.32 in IMRT, VMAT and 3D-CRT, respectively. Conclusion From this study, we can conclude that IMRT and VMAT techniques are feasible and can achieve better dosimetric goals for target and OARs though minimizing the area achieving low dose remains to be a dosimetric concern for VMAT.

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.

Influence of radiation treatment technique (IMRT vs. 3D-RT) on acute toxicity and prognostic factors for survival for anal cancer

We compared our institutional experience with intensity-modulated radiotherapy (IMRT) and 3D-conformal radiotherapy (3D-RT) for definitive treatment of primary anal cancer. We performed a single-institution retrospective review of all patients with anal squamous cell carcinoma treated with definitive (chemo) radiotherapy with curative intent from 2004 through 2018. We assessed several prognostic factors in respect to relevant survival endpoints. In addition, acute toxicities were determined and compared between IMRT and 3D-RT patients. This study included 94 patients (58 IMRT, 36 3D-RT). Mean follow up for all patients, for IMRT and 3D-RT patients was 61 months (range 6–176), 46 months (range 6–118), and 85 months (range 6–176), respectively. 5-year overall survival (OS) was 86%, disease-free survival (DFS) was 72%, and colostomy-free survival (CFS) was 75% in the IMRT cohort. In the 3D-RT cohort, OS was 87%, DFS was 71%, and CFS was 81% (all p > 0.05). Male gender and Karnofsky Index (KI) were revealed as independent prognostic factors for 5-year OS (p = 0.017; p = 0.023). UICC stage was an independent prognostic factor for DFS and CFS (p = 0.023; p = 0.042). In addition, the pre-treatment leukocyte count was an independent prognostic factor for CFS (p = 0.042). Acute grade ≥ 3 toxicity was not significantly different between IMRT and 3D-RT patients, but the IMRT cohort had favorable outcomes. This study confirmed IMRT as the primary definitive treatment of anal cancer. With similar survival rates, IMRT had the potential to reduce acute toxicity by sparing organs at risk. Promising prognostic factors such as BMI, KI, and leucocyte and hemoglobin levels should be further investigated.

Transition from 3D conformal to modern modulated craniospinal radiotherapy

Background: Achieving optimal tumour coverage during craniospinal irradiation (CSI) is a challenge. Whilst several critical organs are at risk of radiation-induced toxicity, if target volume structures like the cribriform plate receive less than 95% of the prescribed dose, tumours could recur.Aim: This single-institution study seeks to establish the most effective craniospinal radiotherapy amongst 3D conformal radiation therapy (CRT), intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) by comparing dosimetry across target volumes, organs at risk (OARs) and total irradiated volume. Time taken for contouring, generation and evaluation of treatment plans, quality assurance and treatment beam delivery is assessed.Setting: The demographics of patients comprised of six children and one adult who underwent 3D CRT craniospinal radiotherapy at a Western Cape hospital.Methods: Approval from the Human Research Ethics Committee was obtained. The 3D CRT plan consisted of two parallel opposing lateral fields at the cranial isocentre and a single posterior field at the spinal isocentre. Both the IMRT and VMAT plans comprised three isocentres, one cranial and two spinal, with a total of 15 fields.Results: Volumetric modulated arc therapy was the most conformal (CI = 0.48) and IMRT the most homogeneous (HI = 0.06). Although the VMAT low-dose bath (58.1%) was highest at 2 Gy, OARs were least exposed with VMAT. The total time taken for VMAT was the shortest.Conclusion: Volumetric modulated arc therapy was recommended as the most effective CSI technique owing to its superior conformality, least OARs exposure and fastest planning times. Clinical investigation into possible late adverse effects arising from the VMAT low-dose bath should be conducted.Contribution: This study will establish which of the three radiation therapy (RT) techniques is most effective in the treatment of craniospinal tumours, as well as, which technique offers the fastest turn around time.

Dosimetric analysis of 3 dimensional conformal radiotherapy with volumetric modulated arc therapy in patients with carcinoma oesophagus – Prospective study

: To study the dosimetry and treatment plan of Volumetric Modulated Arc Therapy and 3 Dimensional Conformal Radiotherapy in patients with carcinoma oesophagus. : A prospective study was taken up in Department of Radiotherapy, from October 2017 to June 2019. A total 20 patients who achieved eligibility criteria was taken into study and both 3D CRT (3D Conformal Radiation Therapy)and VMAT(Volumetric Modulated Arc Therapy ) plans was done in all patients. Dosimetric comparison is done between these two techniques. Dose to spinal cord is significantly reduced with VMAT technique when compared to 3D CRT. VMAT plans in this study showed significantly reduced doses to heart, when compared to 3D CRT plans. VMAT plans decrease volume of lung receiving high dose(v20,dmean,v30,v40) compared to 3D CRT but at a cost of delivering low dose to more volume of lung (v5, v10, v15) resulting in serious complications like radiation pneumonitis. VMAT plans are advisable in carcinoma oesophagus patients to achieve reduced doses to OARs(Organs at Risk) like Spinal Cord, Heart &amp; Lung and better target coverage particularly in cervical esophagus where higher doses are planned.

What We Talk about When We Talk about Artificial Intelligence in Radiation Oncology

The constant evolution of technology has dramatically changed the history of radiation oncology, allowing clinicians to deliver increasingly accurate and precise treatments, moving from 2D radiotherapy to 3D conformal radiotherapy, leading to intensity-modulated image-guided (IMRT-IGRT) and stereotactic body radiotherapy treatments [...].

147 (PB-060) Poster - Oesophagus exposure in hypofractionated breast cancer radiotherapy: an organ at risk commonly overlooked?

Background: Recent evidence related breast cancer radiotherapy to higher risk of subsequent oesophageal cancer in long-term survivors. The aim of this study was to assess radiation dose distribution to oesophagus in modern hypofractionated 3D conformal breast cancer radiotherapy.

Definitive High-Dose Radiotherapy for Primary Vulvar Cancer: The DRIVE Multicenter Cohort Study

<h3>Purpose/Objective(s)</h3> There is limited published data on definitive chemoradiation therapy for vulvar cancer. A retrospective multi-institutional cohort study was conducted to determine the efficacy, patterns of failure and long-term toxicity of high-dose radiation therapy (RT) for the primary treatment of vulvar carcinoma. <h3>Materials/Methods</h3> DRIVE (definitive radiation therapy for primary vulvar cancer) is a multicenter cohort study evaluating outcome for definitive high-dose conformal RT (dRT) for first line treatment of vulvar cancer. Treatment compliance, toxicity and patterns of failure were investigated. Actuarial locoregional control (LRC) and survival (OS) were estimated using Kaplan-Meier method and compared using log rank test. Herein, we present our preliminary results. <h3>Results</h3> In total, 48 patients [median (interquartile range) age, 57 (46-67) years] who received dRT between 2010 and 2020 were analyzed. Median follow-up was 28 (2–113) months. Cohort included 15 (31%) with stage I-II, and 33 (69%) patients with stage III-IV disease. Inguinal nodes alone were involved in 13 patients (27%); 19 (40%) had inguinal and/or pelvic node metastases. Elective surgical staging of groins was performed in 16 (33%) patients, of whom 7 had involved nodes. Intensity-modulated RT (IMRT) was used in 45 (94%) patients, and 3 (6%) received 3D-conformal RT. Median tumor dose was 64Gy (52-74.8Gy). Concurrent platinum-based chemotherapy was administered in 40 (83%) patients (1-8 cycles). Clinical complete response (CR) was achieved in 81.3% (39/48) patients at the primary site, and 84% (27/32) at involved nodes. Eight (16.7%) patients had persistent/recurrent disease following treatment, all within treatment volume; 5 (10%) patients developed distant metastasis. Actuarial 2 and 5-year LRC was 77.7% and 73%, respectively. Two and 5-year overall survival were 71% and 55%, respectively. On univariate analysis, determinants of inferior LRC were stage III/IV (p=0.04), non-IMRT technique (p=0.05) and <2 cycles of chemo (p=0.03). Treatment compliance included 90% (43 patients) completing planned treatment, 11/48 (23%) hospitalization, 6/48 (12.5%) blood transfusion, 12/48 (25%) with >5 days interruptions and median weight loss of 2.6Kg during RT. Of 40 evaluable patients, 25 (63%) developed significant vaginal stenosis. Vulvar necrosis was observed in 5 (10%) patients, all received ≥64Gy [2 treated with hyperbaric oxygen, 1 had musculocutaneous flap-reconstruction]. No acute/chronic grade 3 GI or GU toxicity, or any grade 5 toxicities were seen. <h3>Conclusion</h3> Definitive high-dose RT for vulvar cancer achieves high rates of local control, good compliance with acceptable dose dependent long-term toxicity. Use of IMRT does not result in increased geographic miss and was associated with improved locoregional control over existing prospective data from GOG 205 study.

Reduction in Total On-Table Time for Palliative Radiation Patients Using Pre-Treatment Field Validation

<h3>Purpose/Objective(s)</h3> Palliative radiation therapy is commonly used to help relieve pain, prevent pathologic fracture, and improve quality of life. Physicians often use conventional 2D or 3D conformal radiotherapy to treat these lesions with multi-field arrangements. These fields are traditionally verified with portal images obtained with the patient on the treatment table, to simultaneously evaluate block design accuracy and isocenter position. Unfortunately, this process can be time-consuming as each field needs to be independently and sequentially verified, which can negatively impact patients in pain on the treatment table. Therefore, minimizing total "on-table" time by streamlining the validation process can improve patient experience and quality of life during radiation therapy. Our research investigates an alternative validation process to reduce total on-table time and improve clinic efficiency by validating all fields with port films obtained prior to patient arrival, then verifying isocenter position against patient anatomy using cone beam CT (CBCT). An isodose-line (IDL) surrogate structure was utilized as needed for either block edge (e.g., 50% IDL) or clinically meaningful dose (e.g., 95% IDL) when deemed useful for verification of anatomy within the treatment field. <h3>Materials/Methods</h3> Data was gathered for 172 patients treated for palliation over nine years at a single institution within the VA system. From our record and verify system, "total table time" was acquired – defined as time from initial image procurement to completion of first treatment delivery. Data was analyzed based on patient setup method (PORTs vs. Pre-PORTs + CBCT) in addition to the treatment site. <h3>Results</h3> We found a significant 60% reduction in average on-table time when implementing the Pre-PORTs + CBCT validation method as compared to the traditional PORTs only method. <h3>Conclusion</h3> We report a practical process to verify field design and treatment iso-center while reducing total table time, an important goal especially in palliative cases to minimize pain and improve patient experience during radiation therapy. Additionally, this approach improves workflow and can potentially increase clinic throughput. While cone beam CTs for palliative patients are not always feasible in current reimbursement models, this technique can also improve patient safety and treatment accuracy by automating shifts and limiting table time for combative or altered patients, and thereby might ultimately provide added incentive for changing those models.

Trends in American Radiation Oncology Workforce, Patient Volume and Technology Utilization

<h3>Purpose/Objective(s)</h3> Concerns have arisen within the US radiation oncology (RO) community regarding the current workforce supply-demand imbalance and the future impact of the Centers for Medicare and Medicaid Services (CMS) alternative payment model (APM) on reimbursement and practice patterns. We evaluated trends in RO providers and technology utilization before the RO-APM implementation based on CMS data. <h3>Materials/Methods</h3> We used publicly available CMS Physician and Other Provider Public Use Files from 2012 to 2019. We identified RO providers by the "provider type" field. New patient visits (NPVs) were determined by the 99203, 99204, 99205 CPT codes, treatment plans by the 77261, 77262, and 77263 CPT codes, and on-treatment visits (OTVs) by the 77427, 77431, 77432, and 77435 CPT codes. The total number of yearly fractions per RT modality was defined by relevant CPT codes. We report descriptive statistics and trends in these metrics. These numbers do not include patients enrolled on Medicare Advantage plans, the prevalence of which has increased over the study period. <h3>Results</h3> From 2012 to 2019, the number of RO providers per year in the CMS database increased from 4,135 to 4,612 (+11.5%); the number of Medicare NPVs per year by provider increased by 17% over the same time (220,569 to 257,408). Consequently, the ratio of new patients per provider per year increased slightly (+4.6%); in contrast, the number of treatment plans per provider per year declined (-5.3%). <b>Table 1</b> shows these data numerically. The number of IMRT fractions per year slightly declined (-5.1%); the total number of proton and SBRT/SRS fractions per year increased by 343% and 182%, respectively. Total 3D conformal radiotherapy fractions per year nearly halved (-41%). The number of OTVs per treatment plan declined annually, suggesting a decrease in treatment duration (4.3 to 3.8, -7.3%). In absolute terms, Medicare payments to RO providers declined marginally from 2012 ($1.50 billion USD) to 2019 ($1.43 billion USD); but, when accounting for inflation, this resulted in a 14% decline in RO reimbursement from CMS. <h3>Conclusion</h3> The stable ratio of new patient visits to RO providers suggests that, as of 2019, growth in patient volume resembles growth in ROs; however, there has been an uncoupling of increase in NPVs and treatment plans that may reflect increased omission of RT in situations where RT was previously utilized. RO reimbursement declined before the introduction of the RO-APM. Upon enacting the RO-APM, the appropriate use of technology and hypofractionated courses should be closely monitored in the setting of monetary incentives.

Acute Gastrointestinal Toxicity Results from a Multi-Institution, Phase 2, Randomized Controlled Trial Comparing 3D-Conformal Radiotherapy (3DCRT) Versus Intensity Modulated Radiotherapy (IMRT) for Locally-Advanced Rectal Cancer (TRI-LARC).

<h3>Purpose/Objective(s)</h3> The primary aim of this trial was to compare the incidence of grade 2 or above acute gastrointestinal (GI) toxicity for patients undergoing 3DCRT versus IMRT in the preoperative setting for locally-advanced rectal cancer. Secondary objectives included quality of life and other acute and late toxicity. <h3>Materials/Methods</h3> The trial was designed to have 80% power to detect a difference between a hypothesized 37% acute toxicity rate in the 3DCRT arm (Bosset et al, 2006) and 20% in the IMRT arm, with a sample size of 120 per arm, and a 0.05 two-sided level of significance. Eligible participants were adults aged 18 or over scheduled to receive pre-operative pelvic chemo-radiotherapy for histologically-confirmed rectal adenocarcinoma. Exclusion criteria included prior pelvic radiotherapy, inflammatory bowel disease, hip replacements, and previous bowel surgery. Prescription dose was 50.4 Gray in 28 fractions over 5.5 weeks with concurrent 5-fluorouracil or capecitabine chemotherapy. Participants were centrally randomized 1:1 to receive 3DCRT or IMRT. Each individual radiotherapy volume and plan was reviewed centrally to ensure compliance with the trial's RTQA specifications. Toxicity was graded and reported according to CTCAE version 4.0 (National Institutes of Health National Cancer Institute). Acute toxicity was assessed weekly during radiotherapy, and at 2- and 4-weeks post-treatment. <h3>Results</h3> 94 patients were enrolled. 77% were male and median age was 59.4. Two participants from the 3DCRT arm did not complete radiotherapy as planned and were excluded from analysis. 25 (56%) of participants from the 3dCRT arm and 23 (49%) from the IMRT arm experienced acute grade 2 or above GI toxicity (p=.670). Rates for grade 3 GI toxicity were 8 (18%) and 5 (11%) for 3dCRT and IMRT, respectively (p=.494). Grade 3 GI events included diarrhea (n=11), nausea (n=2), intestinal obstruction (n=1), oral mucositis (n=1), and rectal pain (n=1). The study closed early due to absence of evidence of a difference between arms at the interim analysis. <h3>Conclusion</h3> No significant difference in rates of acute GI toxicity with IMRT versus 3DCRT for locally advanced rectal cancer was seen. Although IMRT can reduce dose to organs at risk, it appears to be similarly safe in terms of acute GI toxicity to deliver this treatment with 3DCRT.

Quality of Life Analysis of a Phase II Randomized Controlled Trial Comparing 3D-Conformal Radiotherapy (3D-CRT) and Intensity Modulated Radiotherapy (IMRT) in Locally Advanced Rectal Cancer (TRI-LARC)

<h3>Purpose/Objective(s)</h3> The aim of the study was to compare the use of 3D-CRT and IMRT in pre-operative long course chemo-radiotherapy for locally advanced rectal cancer. We herein evaluate the impact of the two treatment modalities on quality of life (QOL), a secondary objective of the study. <h3>Materials/Methods</h3> 94 patients with rectal adenocarcinoma were enrolled in a prospective randomized phase II trial across three institutions between 2014 and 2020. Eligible patients had stage T3-4, N(any) or circumferential resection margin at risk with no evidence of metastatic disease. All patients were prescribed 50.4Gy in 28 fractions with concomitant 5-fluorouracil or capecitabine. Patients were randomly assigned (1:1) to 3D-CRT and IMRT planning techniques. QOL was assessed using the EORTC QLQ C30 and QLQ CR29 questionnaires at baseline, during the final week of radiotherapy and at six and twelve months after radiotherapy. A paired sample t test was used to compare differences in QOL from baseline to each follow-up. One-way between-group analyses of covariance (ANCOVA) were conducted to compare the effect of the trial arms on each QOL score. <h3>Results</h3> At a median follow-up of 14 months, the trial was terminated early due to failure to establish efficacy in the primary outcome, acute gastrointestinal toxicity. The median age was 59 years and 72/94 (77%) were male. 86/94 (91%) patients completed the baseline and at least one other QOL assessments. QOL data at one year was available in 55/94(58%). At baseline, there was no difference in QOL scores between trial arms. Overall, emotional functioning had improved at six months but physical, cognitive, role and social functioning had declined. At six months, there was a significant improvement in constipation, blood and mucous in stool, bloating, urinary frequency, buttock pain and anxiety scores compared to baseline. There was a significant deterioration in dyspnea, fatigue, nausea/vomiting, taste, hair loss, erectile dysfunction, body image and global health scores from baseline to 6-month follow-up. After adjusting for pre-intervention score, the IMRT arm had better physical functioning (p=0.038) and role functioning (p=0.014) during the final week of radiotherapy compared to the 3DCRT arm. The end of radiotherapy embarrassment score, for those without a stoma, was significantly worse in the IMRT arm (p=0.032). There was no other significant difference in QOL scores between the two arms, at either the final week of radiotherapy or at 6 months, after adjustment for pre-intervention scores. The limitations of the study include its early termination, the potential for type 1 error and the possible influence of other factors on QOL data such as chemotherapy and postoperative complications. <h3>Conclusion</h3> There are limited QOL benefits of IMRT compared to 3D-CRT in the neoadjuvant setting for rectal cancer.

Anal squamous cell carcinoma: Impact of radiochemotherapy evolution over years and an explorative analysis of MRI prediction of tumor response in a mono-institutional series of 131 patients.

Radiochemotherapy (RCHT) for the treatment of anal squamous cell carcinoma (ASCC) has evolved dramatically, also thanks to intensity-modulated RT (IMRT) and 3D image guidance (3D IGRT). Despite most patients presenting fair outcomes, unmet needs still exist. Predictors of poor tumor response are lacking; acute toxicity remains challenging; and local relapse remains the main pattern of failure. Between 2010 and 2020, ASCC stages I-III treated with 3D conformal radiotherapy or IMRT and CDDP-5FU or Mytomicine-5FU CHT were identified. Image guidance accepted included 2D IGRT or 3D IGRT. The study endpoints included freedom from locoregional recurrence (FFLR), colostomy free survival (CFS), freedom from distant metastasis (FFDM), overall survival (OS), and acute and late toxicity as measured by common terminology criteria for adverse events (CTCAE) version 5.0. An exploratory analysis was performed to identify possible radiomic predictors of tumor response. Feature extraction and data analysis were performed in Python™, while other statistics were performed using SPSS® v.26.0 software (IBM®). A total of 131 patients were identified. After a median FU of 52 months, 83 patients (63.4%) were alive. A total of 35 patients (26.7%) experienced locoregional failure, while 31 patients (23.7%) relapsed with distant metastasis. Five year FFLR, CFS, DMFS and PS resulted 72.3%, 80.1%, 74.5% and 64.6%. In multivariate analysis, 2D IGRT was associated with poorer FFLR, OS, and CFS (HR 4.5, 4.1, and 5.6, respectively); 3DcRT was associated with poorer OS and CFS (HR 3.1 and 6.6, respectively). IMRT reduced severe acute gastro-intestinal (GI) and severe skin acute toxicity in comparison with 3DcRT. In the exploratory analysis, the risk of relapse depended on a combination of three parameters: Total Energy, Gray Level Size Zone Matrix's Large Area High Gray Level Emphasis (GLSZM's LAHGLE), and GTV volume. Advances in radiotherapy have independently improved the prognosis of ASCC patients over years while decreasing acute GI and skin toxicity. IMRT and daily 3D image guidance may be considered standard of care in the management of ASCC. A combination of three pre-treatment MRI parameters such as low signal intensity (SI), high GLSZM's LAHGLE, and GTV volume could be integrated in risk stratification to identify candidates for RT dose-escalation to be enrolled in clinical trials.