Quality and Safety Considerations in Intensity Modulated Radiation Therapy: An ASTRO Safety White Paper Update.

PURPOSE: This updated report on intensity modulated radiation therapy (IMRT) is part of a series of consensus-based white papers previously published by the American Society for Radiation Oncology (ASTRO) addressing patient safety. Since the first white papers were published, IMRT went from widespread use to now being the main delivery technique for many treatment sites. IMRT enables higher radiation doses to be delivered to more precise targets while minimizing the dose to uninvolved normal tissue. Due to the associated complexity, IMRT requires additional planning and safety checks before treatment begins and, therefore, quality and safety considerations for this technique remain important areas of focus. METHODS AND MATERIALS: ASTRO convened an interdisciplinary task force to assess the original IMRT white paper and update content where appropriate. Recommendations were created using a consensus-building methodology, and task force members indicated their level of agreement based on a 5-point Likert scale, from "strongly agree" to "strongly disagree." A prespecified threshold of ≥75% of raters who select "strongly agree" or "agree" indicated consensus. CONCLUSIONS: This IMRT white paper primarily focuses on quality and safety processes in planning and delivery. Building on the prior version, this consensus paper incorporates revised and new guidance documents and technology updates. IMRT requires an interdisciplinary team-based approach, staffed by appropriately trained individuals as well as significant personnel resources, specialized technology, and implementation time. A comprehensive quality assurance program must be developed, using established guidance, to ensure IMRT is performed in a safe and effective manner. Patient safety in the delivery of IMRT is everyone's responsibility, and professional organizations, regulators, vendors, and end-users must work together to ensure the highest levels of safety.

Strategies for effective physics plan and chart review in radiation therapy: Report of AAPM Task Group 275.

BACKGROUND: While the review of radiotherapy treatment plans and charts by a medical physicist is a key component of safe, high-quality care, very few specific recommendations currently exist for this task. AIMS: The goal of TG-275 is to provide practical, evidence-based recommendations on physics plan and chart review for radiation therapy. While this report is aimed mainly at medical physicists, others may benefit including dosimetrists, radiation therapists, physicians and other professionals interested in quality management. METHODS: The scope of the report includes photon/electron external beam radiotherapy (EBRT), proton radiotherapy, as well as high-dose rate (HDR) brachytherapy for gynecological applications (currently the highest volume brachytherapy service in most practices). The following review time points are considered: initial review prior to treatment, weekly review, and end-of-treatment review. The Task Group takes a risk-informed approach to developing recommendations. A failure mode and effects analysis was performed to determine the highest-risk aspects of each process. In the case of photon/electron EBRT, a survey of all American Association of Physicists in Medicine (AAPM) members was also conducted to determine current practices. A draft of this report was provided to the full AAPM membership for comment through a 3-week open-comment period, and the report was revised in response to these comments. RESULTS: The highest-risk failure modes included 112 failure modes in photon/electron EBRT initial review, 55 in weekly and end-of-treatment review, 24 for initial review specific to proton therapy, and 48 in HDR brachytherapy. A 103-question survey on current practices was released to all AAPM members who self-reported as working in the radiation oncology field. The response rate was 33%. The survey data and risk data were used to inform recommendations. DISCUSSION: Tables of recommended checks are presented and recommendations for best practice are discussed. Suggestions to software vendors are also provided. CONCLUSIONS: TG-275 provides specific recommendations for physics plan and chart review which should enhance the safety and quality of care for patients receiving radiation treatments.

Evaluation of radiation-induced cardiac toxicity in breast cancer patients treated with Trastuzumab-based chemotherapy.

PURPOSE: Patients with Her2-positive breast cancer treated with trastuzumab have higher rates of cardiotoxicity (CT). Left-breast radiation might increase the risk for CT from cardiac exposure to radiation. The goal of our study is to evaluate the contribution of radiotherapy (RT) in the development of CT in breast cancer patients receiving trastuzumab. METHODS: Two hundred and two patients were treated with RT and trastuzumab from 2000 to 2014. The RT plans for left-side disease were recalled from archives. The heart, each chamber, and left anterior descending artery (LAD) were independently contoured. New dose-volume histograms (DVH) were generated. Their serial left-ventricular ejection fractions (LVEF) were studied. CT for left and right side were compared using Fisher's exact test. The DVH data were correlated with the predefined cardiac events using actuarial Cox regression analysis. RESULTS: Compared to the right sided, the left-side cases showed statistically significant development of arrhythmia (14.2%) versus (< 1%) (p < 0.001). Cardiac ischemia was found in 10 patients in left and one patient in right side (p = 0.011). The equivalent uniform dose (EUD) to the left ventricle (LV), right ventricle (RV), and LAD was significantly associated with decrease in LVEF by > 10% (p = 0.037, p = 0.023 and p = 0.049, respectively). CONCLUSIONS: Among patients treated for left-sided lesions, there were no significant differences in EF decline. However, there was a higher rate of ischemia and arrhythmia compared to those with right-sided disease. The EUD index of LV, RV, and LAD could be considered as a parameter to describe the risk of radiation-induced CT.

Clinical and treatment factors associated with vaginal stenosis after definitive chemoradiation for anal canal cancer.

PURPOSE: We sought to evaluate the incidence of vaginal stenosis (VS) and identify clinical and treatment factors that predict for VS in female patients with anal cancer treated with definitive chemoradiation. METHODS AND MATERIALS: The cohort included 95 consecutive women receiving definitive chemoradiation between 2003 and 2012. All but 1 received intensity modulated radiation therapy; median primary tumor dose 50.4 Gy (range, 41.4-60). A modified National Cancer Institute Common Terminology Criteria for Adverse Events version 4 was used to score VS based on the medical record description of dyspareunia, pain with dilator use, vaginal dryness, or difficult pelvic examination. Ordered logistic regression was performed to assess VS predictors. RESULTS: Median age was 60.4 years (range, 19-97). With median follow-up of 2.5 years, 70 women (74%) had adequate information to assess VS. Of these, VS grade distribution was 21.4% grade 0, 14.3% grade 1, 27.1% grade 2, and 37.1% grade 3. By multivariable ordered logistic regression, younger age (P = .02), higher tumor dose (P = .06), and earlier treatment year (P = .04) were associated with higher grade of VS. CONCLUSIONS: VS is a common late complication in women treated definitively with chemoradiation for anal canal cancer. Younger age, higher tumor dose, and earlier year of treatment were associated with a higher grade of stenosis. Prospective investigation into patient reported outcomes is warranted, including sexual function and VS prevention strategies to better understand its effect on long-term survivorship.

Deep inspiration breath-hold technique in left-sided breast cancer radiation therapy: Evaluating cardiac contact distance as a predictor of cardiac exposure for patient selection.

PURPOSE: The purpose of this study was to evaluate the efficacy of voluntary deep inspiration breath-hold (DIBH) over a free-breathing (FB) technique to minimize cardiac radiation exposure in radiation therapy of left-sided breast cancer. Also, to better select patients for DIBH, the correlation between cardiac contact distance (CCD) and cardiac dose was assessed. METHODS AND MATERIALS: Thirty-five patients with left-sided breast cancer underwent DIBH and FB planning computed tomography scans, and the 2 plans were compared. Dose-volume histograms were analyzed for heart, left anterior descending coronary artery (LAD), left ventricle (LV), and left lung. Axial CCDs and parasagittal CCDs (FB-CCDps) were measured on FB planning computed tomography scans. RESULTS: Dose to heart, LAD, LV, and left lung was significantly lower in DIBH plans than in FB by all metrics. When DIBH was compared with FB, mean dose (Dmean) for heart was 0.9 versus 2.5 Gy; for LAD, 4.0 versus 14.9 Gy; and for LV, 1.1 versus 3.9 Gy (P < .0001), respectively. Seventy-five percent of the patients had a dose reduction of ≥ 0.9 Gy in Dmean to heart, ≥ 3 Gy in Dmean to LAD, and ≥ 1.7 Gy in Dmean to LV. FB-CCDps was associated with an equivalent uniform dose to heart, LAD, and LV for both the DIBH and FB plans (P ≤ .01); FB axial CCD measures were not. CONCLUSIONS: DIBH is a simple and highly effective technique to reduce cardiac exposure without compromising target coverage. FB-CCDps is potentially a very good predictor for cardiac exposure: the longer the FB-CCDps, the higher the dose. Our findings suggest that at least 75% of patients with left-sided breast cancer might benefit from the DIBH technique in terms of potentially clinically relevant dose reduction to cardiac structures, and therefore, it should be instituted as routine clinical practice.

Phase I study of neoadjuvant accelerated short course radiation therapy with photons and capecitabine for resectable pancreatic cancer.

PURPOSE: In this phase I study, we sought to determine the feasibility and tolerability of neoadjuvant short course radiotherapy (SC-CRT) delivered with photon RT with concurrent capecitabine for resectable pancreatic adenocarcinoma. MATERIALS AND METHODS: Ten patients with localized, resectable pancreatic adenocarcinoma were enrolled from December 2009 to August 2011. In dose level I, patients received 3 Gy × 10. In dose level 2, patients received 5 Gy × 5 (every other day). In dose level 3, patients received 5 Gy × 5 (consecutive days). Capecitabine was given during weeks 1 and 2. Surgery was performed 1-3 weeks after completion of chemotherapy. RESULTS: With an intended accrual of 12 patients, the study was closed early due to unexpected intraoperative complications. Compared to the companion phase I proton study, patients treated with photons had increased intraoperative RT fibrosis reported by surgeons (27% vs. 63%). Among those undergoing a Whipple resection, increased RT fibrosis translated to an increased mean OR time of 69 min. Dosimetric comparison revealed significantly increased low dose exposure to organs at risk for patients treated with photon RT. CONCLUSIONS: This phase I experience evaluating the tolerability of neoadjuvant SC-CRT with photon RT closed early due to unexpected intraoperative complications.

Intensity modulated proton therapy for postmastectomy radiation of bilateral implant reconstructed breasts: a treatment planning study.

BACKGROUND AND PURPOSE: Delivery of post-mastectomy radiation (PMRT) in women with bilateral implants represents a technical challenge, particularly when attempting to cover regional lymph nodes. Intensity modulated proton therapy (IMPT) holds the potential to improve dose delivery and spare non-target tissues. The purpose of this study was to compare IMPT to three-dimensional (3D) conformal radiation following bilateral mastectomy and reconstruction. MATERIALS AND METHODS: Ten IMPT, 3D conformal photon/electron (P/E), and 3D photon (wide tangent) plans were created for 5 patients with breast cancer, all of whom had bilateral breast implants. Using RTOG guidelines, a physician delineated contours for both target volumes and organs-at-risk. Plans were designed to achieve 95% coverage of all targets (chest wall, IMN, SCV, axilla) to a dose of 50.4 Gy or Gy (RBE) while maximally sparing organs-at-risk. RESULTS: IMPT plans conferred similar target volume coverage with enhanced homogeneity. Both mean heart and lung doses using IMPT were significantly decreased compared to both P/E and wide tangent planning. CONCLUSIONS: IMPT provides improved homogeneity to the chest wall and regional lymphatics in the post-mastectomy setting with improved sparing of surrounding normal structures for woman with reconstructed breasts. IMPT may enable women with mastectomy to undergo radiation therapy without the need for delay in breast reconstruction.

A single-nucleotide polymorphism in the methylene tetrahydrofolate reductase (MTHFR) gene is associated with risk of radiation pneumonitis in lung cancer patients treated with thoracic radiation therapy.

BACKGROUND: This study examined the association between functional single-nucleotide polymorphisms in candidate genes from oxidative stress pathways and risk of radiation pneumonitis (RP) in patients treated with thoracic radiation therapy for locally advanced lung cancer. METHODS: A review was conducted of 136 patients treated with radiation therapy for lung cancer between 2001 and 2007, and who had prior genotyping of functional single-nucleotide polymorphisms in oxidative stress genes including superoxide dismutase 2 (SOD2; rs4880) and methylene tetrahydrofolate reductase (MTHFR; rs1801131, rs1801133). RP events were retrospectively scored using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. Cox proportional hazard regression was performed to identify clinical variables and genotypes associated with risk of RP of grades ≥2 and ≥3 on univariate and multivariate analysis, respectively. P values were corrected for multiple hypothesis esting. RESULTS: With a median follow-up of 21.4 months, the incidence of grade ≥2 RP was 29% and grade ≥3 RP was 14%. On multivariate analysis, after adjusting for clinical factors such as concurrent chemotherapy and consolidation docetaxel, and lung dosimetric parameters such as volume receiving greater than 20 Gy and mean lung dose, MTHFR genotype (rs1801131; AA versus AC/CC) was significantly associated with risk of grade ≥2 RP (hazard ratio: 0.37; 95% confidence interval: 0.18-0.76; P = .006, corrected P = .018) and grade ≥3 RP (hazard ratio: 0.21; 95% confidence interval: 0.06-0.70; P = .01; corrected P = .03). SOD2 genotype was not associated with RP. CONCLUSIONS: This study showed an association between MTHFR genotype and risk of clinically significant RP. Further study of MTHFR-related pathways may provide insight into the mechanisms behind RP.

Nanoparticle-enhanced MRI to evaluate radiation delivery to the regional lymphatics for patients with breast cancer.

PURPOSE: At present, radiation (RT) fields are based largely, and often solely, on bony anatomy. Recent efforts have been taken to better define lymphatic regions for RT planning. Lymphotrophic nanoparticle-enhanced MRI (LN-MRI) allows for accurate identification of malignant and benign lymph nodes. We sought to evaluate RT delivery to lymphatics for breast cancer using LN-MRI. METHODS AND MATERIALS: Twenty-three patients with breast cancer underwent LN-MRI. MRIs were anatomically registered to a reference CT; benign and malignant lymph nodes were contoured. Standard RT fields were planned and dose calculated to prescribe 45-50 Gy. Lymphatic regions were contoured on CT. Coverage of LN-MRI lymph nodes by RT fields and contoured lymphatics were assessed. RESULTS: Eighty-one percent of all lymph nodes defined by LN-MRI were covered by the 45-Gy isodose line; 82% of malignant and 79% of benign. The 50-Gy isodose line only encompassed 60% of LN-MRI defined lymph nodes-64% of malignant and 59% of benign. For nodal volumes contoured in the absence of a margin, 86% of actual lymph nodes were within contoured volumes. When a 5-mm expansion was added, 99% were included. CONCLUSIONS: LN-MRI is a useful tool to delineate the location of breast regional lymphatics. These results suggest less than desired coverage of lymph nodes using standard RT fields and that a margin may be advisable when defining nodal volumes by CT. The use of IMRT and RT in lieu of surgery makes accurate definition of the location of breast regional lymphatics of paramount importance.